FEBRUARY 2007

www.el ektor-electronics.co.uk

EXPLORER

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tests* measurement

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POST AND PACKING CHARGES:
Order Value Cost Order Value Cosj
£20 - £49.99 £5 £200 - £499.99 £30

£50 - £99.99 £10 £500* £40

£100 * £199.99 £20

Max weight 12lb {5kg). Heavier
parcels POA. Minimum order £20.

Hole: Products ars dispatched nom Australis.
3c cel customs duly and taxas may app’y.

DC Relay Switch

KC-5434 £4.50

post & packing
An extremely useful and versatile kit that
enables you to use a tiny trigger current - as
tow as 400pA at 12 V to switch up to 3QA at
50VDC. It has an isolated input, and is suitable
for a variety of triggering options.

The kit includes PCD with
overlay and all electronic
components with clear English
instructions. pa

Radar Speed Gun *

I KC-5429 £29.00 + post 8* packing A i r- : '
This Dappler nadar gun reads speed
in km/h or mph up to 250 km/h or
155 mph. It has a resolution of 1 km/h or 1 mph
with an accuracy of 1 9b, and also has a hold switch
so you can freeze the reading.

There's a jiffy box to mount the /* -

electronics in, and the enclosure / j ffip Mgp
for the radar gun assembly is /
made from 1 x coffee tins or / J

similar. Details included. Kit / ®

includes PCB and all specified I J

components with dear /

English instructions. / - Z^rg?-*

■ Requires 12VDC power, ^ M

Magnetic Cartridge Pre-amp A**

KC-5433 £1 1+75 + post &. packing O^Saj

This kit is used to amplify the 3-4mV signals^*:
from a phono cartridge to line level, so you can
use your turntable with the CD or tuner inputs o
your Hi-Fi amplifier. The design is suitable for 12
LPs, and also allows for RIAA equalisation of all
the really old 70s, Please note that the input
sensitivity of this design means it's
only suitable for moving-magnet, G v .
not moving -coil cartridges. Kit AB^WS

includes PCB with overlay '

and all electronic fc lifc

components. jflaPj

- Requires 12 VAC J

power 'fra miir^

Galactic Voice Kit

KC-5431 £13.25 -r post & packing

0e the envy of everyone at the next

Interplanetary Conference

for Evil Geings with this ■■

galactic voice simulator BLl_ \

kit Effect and depth

controls allow you to /,

vary the effect ro

simulate everything y

from the metallically- X_

challenged C-3 PQ, to the

hysterical ranting of Daleks 1

hell-bent on exterminating ™

anything not nailed down. The kJt includes PCS

with overlay, enclosure, speaker and all

components. For those who really need to get out

of the house a lot more. Take me to your leader.

* Requires 9V battery

[R Remote Control , a

Extender MKII

KC-5432 £7.25 + post & packing
Operate your DVD player or digital decoder using
its remote control from another room, it picks up
the signal from the remote control and sends it via
a 2-wire cable to an infrared LED located close to
the device. This improved model features fast data
transfer, capable of transmitting Fox tel digital
remote control signals using the Pace 400 series
decoder. Kit supplied with i / ^

case, screen printed

front panel, PCS with -BgHK^ M ° Vec

overlay and all electronic

components.

Requires 9VDC wall lIkL IH1

adaptor (Maplin Bj)

=GS74R £10.99)

High Range Adjustable "v

Temperature Switch for Cars

KC-5376 £22.75 -r post & packing

This temperature switch can be set anywhere up

to 1200 ; C, so it is extremely versatile. The relay

can be used to trigger an extra thermo fan on an

intercooler, a sensor near your turbo manifold to

trigger water spray cooling, or a simple buzzer to

indicate high temperature. The LCD displays the

temperature constantly and

can easily be dash >

mounted. Kit ^ ^

included PCB with W, j ■, l ^ ' jjJ

overlay and all &JI , h

electronic components TP

with dear English •'

i nstru cti on s. l\\% ^ ^ B

Universal High Energy Ignition Kit

KC-5419 £27.75 + post & packing

A high energy 0.9ms spark bums fuel Faster and

more efficiently to give you more power! This

versatile kit can be connected to .-

conventional points, twin

points or reluctor ignition = r ^

systems. Kit supplied with

diocast case, PCB „ , — -c ^il

and all electronic

components.

Speedo Corrector Mkll

KC-543 5 £14.50 + post & packing

When you modify your gearbox, cliff ratio or
change to a large circumference tyre, it may
result in an Inaccurate speedometer. This kit
alters the speedometer sfgnalupor down from
O^b to 99^5 of the original signal. With this
improved model, the input set-up selection can
be automatically selected and It also features an
LED indicator to show when the input
signal is being received. Kit
supplied with PCB with 0

overlay and ail electronic „
components with q yjfl jT*?-. '

dear English :

instructions. . V

Powertool Battery
Charger Controller

KC-5436 £11.75 -f post & packing

Enhance the performance of the charger supplied

with your power tool with this controller. It

incorporates charge timeout, min and max

temperature monitoring. Delta charge detection,

power and charge LED indicator, adjustable Delta

V, temperature settings, and f *=***—- „ ,

optional adjustable trickle / #

charge. Suits both Ni-Cd isp**

and Ni-MH cells. Kit L.

includes PCB with overlay,

case, all electronic !%* e * jm

components and dear B

English instructions.

Ah prices
in £ Slg

Free

410+ page i
Cala1ogue_^“

Log on to

www.jaycc'rrelectmnics. go. u !</ elekto r

for your FREE catalogue!

OSOO 032 7241 B

(Monday - Friday 09.00 to 17.30 GMT + 10 hours only),
for those who want to write: 10D Silverwater Rd
Silverwatcf NSW 2128 Sydney AUSTRALIA

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DSO Test Instrument Software for BitScope Mixed Signal Oscilloscopes

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BitSwfA

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4 Channel BitScope

2 Channel BitScope

Pocket Analyzer

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BitScope DSO Software for Windows and Linux

BitScope DSO is fast and intuitive multi-channel test and measurement software for your
PC or notebook. Whether 'rt : s a digital scope, spectrum analyzer, mixed signal scope,
logic analyzer, waveform generator or data recorder, BitScope DSO supports them all.

Capture deep buffer one-shots or display waveforms live just like an analog scope.
Comprehensive test instrument integration means you can view the same data in
different ways simultaneously at the click of a hunom

DSO may even be used stand-alone to share data with colleagues, students or
customers, Waveforms may he exponed as portable image tIEes or live captures replayed
on other PCs as if a BitScope was locally connected.

BitScopa DSD supports alt current BitScope models, auio-configures when it connects
and can manage multiple BllScopes concurrently. No manual setup is normally required*
Data export is available for use with third party software tools and BitScope s networked
data acquisition capabilities are fully supported.

Digital Storage Oscilloscope

Up to 4 analog channels using industry standard
probes or POD connected analog inputs.

Mixed Signal Oscilloscope

Cap lure and display up Eo 4 analog and 8 logic

Spectrum Analyzer

Integrated real-time spectrum analyzer for each
analog channel with concurrent waveform display.

Logic Analyzer

8 logic. External Trigger and special purpose
inputs to capture digital signals down to 25nS

Data Recorder

Record anything DSO can capture. Supports
five data replay and display export*

Networking

Flexible network connectivity supporting
mutli-scope operation, remote monitoring and
data acquisition.

Data Export

Export data with DSO using portable CSV fMes or
use libraries to bufld custom BitScope solutions.

y

Poke 1 6384, #FF

After o period of noticeable decline,
reportedly owing to o bcogieman
called surface-mount assembly (again
reportedly, a descendant of transis-
tor) there are now clear signs^hat
electronics as a pastime is on the up
again albeit in a different appear-
ance. Where a soldering iron, tweez-
ers and o drawer full of colourful
ports were traditionally used to create
electronics on a workbench as well
as demolish it again or repair it down
to the component level , nowadays
engineers think in terms of FPGAs,
circuit boards, FedEx, helpdesks and
firmware they can flash (pun in-
tended), No hardware if it can t talk
software" is hip, but nothing new.
About 20 years ago some friends of
mine bought a von load full of boards
and other parts off a computer manu-
facturer that went belly up after miss-
ing a government order for PCs to
be used nationwide in schools. After
assembling and powering up one of
the ZBO-bosed computers, light smoke
started to curl from one of the plug-in
boards. While several of the gang
frantically traced the power cord
buried in a tangled heap of wires,
one team member sat down at the
keyboard and asked in utter serious-
ness if anyone knew the address, in
decimal or hexadecimal, of the ZBO
port line used to monitor the supply
voltage? Could the line be XORed?
No? Why not? He still managed to
launch BASIC (from ROM} but before
being able to Finish what must have
been the Fourth program line, the
screen went dead and the computer
called it quits. As it turned out, a
wrong voltage regulator had been fit-
ted on one of the plug-in boards and
the repair, by another team member
versed in hardware, took less than
1 5 minutes.

Today, circuit repair is often said
to be a waste of time owing to the
complexity of modern equipment and
the use of block box technology. 1
could not disagree more — defective
or surplus to requirements" as it may
be, any piece of new-fangled elec-
tronics has some component you con
reuse, or ot least try to understand
how it works.

Jan Buiting

Editor

Model constructors really like to see all sorts of flight
data (telemetry). But how do they get hold of this
data, when the rocket is soaring off at an altitude of
500 m or more? A cable is not an option. This circuit

nevertheless shows you how to do this.
Telemetry is taking off, literally!

Happy Hour i f*™, mi

free article downloads from

9,00 am - 9*00 pm GMT

1

1

I

1

i

j

1 8 Flying Robots

Sophisticated robots now assist or even replace us in diffi-
cult or hazardous environments. This is particularly true of
military hardware where we have seen on our TV screens
the use of unmanned aircraft and vehicles in some recenl
conflicts. The basic idea however is not so new; we take a
look info the world of drones'...

32 Explorer- 16 (2]

We continue with a look of
the hardware to go with this
article series brought to you
exclusively by Labcenter,
Microchip UK ond Elektor.
software is covered, too, by
a Proteus VSM simulation of
audio signal processing. And
finally there's a super discount
offer waiting for you.

Volume 33
February 2007
hq» 362

know-how

1 8 Flying Robots

hands-on

32 Explorer-1 6 (2)

40 MP3 Preamp

46 A Telling Way of Telling
the Time

58 FPGA Course (9, final)

l-Q: a Highly Intelligent
Approach to Quality Radio

66 Toilet Guardian

69 Design Tips

IDO regulator

Bicolour LEDs operated by LDR

72 E-blocks LED Chaser

1 8 Flying Robots
24 3,2, 1 , Takeoff!

Accurate Measurements
for a Fiver?

£5 for a digital multimeter
with several extra functions
and a set of leads! Surely that
isn't enough to manufacture a
decent piece of equipment? To
out how useful such a muifi-
is and how accurate it is, we
ught a cheap multimeter and gave it
thorough investigation.

info & market

6 Colophon
8 Mailbox
1 2 High Power (LEDs)

1 4 News & New Products
Sneak Preview

infotainment

76 Philips SFM41 1/100
Wobbulator (1952)

77 Hexadoku

lektor

l@ctronies

Volume 33, Number 362, Februuary 2007 ISSN Q26E AS 19

*

'.[fir Ehcuonics. aims si jrupiirmg pec-pig to miigtgr 31 any personal

level by presenting cons true lion prefects ar.d spaaing developments in

e?enrCft:G end tnfDrmaUDr* tethngfegy.

Publishers E'e*.li 2 v Eearcr .. Nc -r; --e“:r-r

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International edi torial stiff: Harr? B a^er. T i i Bet^ejv -— -7 >:r^rnp= %^^
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Distribution: Seymour, 2 Bst fbi Aty Street Lomfcsi EC I A. fennel
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UK Advertidng: Husoft Intemaf^*^; Meek. Csmbndgs House, G c^ r xj<e late*

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DLSciiimer

P 2=1 -‘H *=*rr^ 32",3- &7X- . _ 2 . Ji-T-'Ii f .

© Segment b.v, 2007 Pnmed in the Netherlands

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dE&tor detfiBniu - 2/2QQ7

in mlkroElektronika

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INFO & MARKET

MAILBOX

thank* for that Jeremy, and congratulations to all students on
completing the project For the 2007 curriculum you may want
to consider the two RFID reader designs a ad the free RFID card
supplied with the September 2006 issue. Let us know how you
gel on.

ps: I devour every issue of your magazine!

Jeremy replies:

Jan — I was the first to order your RFID kit which ! have and
am also building the other design as well! I hove built many
of your projects and never had o problem. Last year our
class built the SC Analyzer 2005 with great success. So far:

- DRM Receiver March 2004

- SC Analyzer April 2005

- GPS Receiver on USB June 2005

- Electrosmog Detector June 2005

RFID Reader classroom project

Dear Sir — I teach electronics at Seneca College in Toronto,
Canada. This fall my APE553 Electronics class built the
TIRIS RFID Reader as described in your October 2005
issue. This was on excellent construction project. Students
created their schematic diagrams and printed circuit board
layouts using the freeware edition of Eagle. Their printed
circuit boards were built using an LPKF milling machine that
our department has. Most students built the simple version
or the circuit and a Few others built the more complicated
version. Construction was straightforward. I used a KANDA
AVR-TRAIN system to program the AT90S1200 mlcrcKon-
trollers. My thanks to Martin Ossmann for designing this
circuit. We have a troubleshooting manuai and typical
board layouts for anyone interested.

Jeremy Clark

Go with the Flow
Dear Sir — I am writing regar-
ding the Go with the Flov/
article in your December
2006 issue. 1 found it some
what scary that you actually
suggest people should endan-
ger their own health just to try
to save a few pennies.
Bacteria, mainly legionella

(http:/ / ww w. I eg i o net I a .
org/engineers.htm#a7) easily
start to reproduce in piping
where the temperature falls
below safe levels. Same thing
applies to Kolera and others.
Most countries actually have
legislation that simply makes
this kind of tampering besides
being utterly stupid, also

May 2006 issue, and it works
fine. 1 used a metal box case
to make it. I posted the story
on the construction process on
my blog at this url:

http:/ /rad i kaldesig . biogspot.
com/2006/ 1 0/insaladoro-uv-
Ieds.html

Thanks for a goad ideal
Droky (on Hlektor Forum)

directly illegal.

Since I am not a resident in
the UK I don't know whaf
the law is over there but on

0 European Union scale I
would soy your article is very
questionable.

There are good reasons
why the temperature in the
circulation pipes should
be kept obove 1 25-
1 40 F depending on
your local regulations.

1 would recommend you
check with your legal
dept and you might want to
come with a advisory not
to implement this project at
any circumstances in your
next issue.

Otto Keren en (Finland}

Jurgen MaiB, the author ■' desig-
ner of the project, replies:
Initially we also considered the
concerns eve' bacteria growth
[in ho! water pipes]. However
according to specialists, the
g rowth is c o r d itianed main >• b>
a tCa low intake temperature or
boiler temperature * Also, cam-
mere in equipment free y ovaiia.
hie horn heating and plumbic::
suppliers : s also affected by this
problem .

In principle, any user should
decide hr hr.:, 'herself >’ com n u-
ous hot water] circulation at 7Q
decrees C 5 o rsauiremenf.

This particular project has drawn
a lot of attention, reported// also
in the forum ^ of our esteemed
competitor EPE magazine. It
■works a treat and con bs mode
to measure to suit persona'
requirements .

Spot welding
with capacitors
Dear editor — regarding the
article Spot welding with
capacitors in the November
2006 issue (Modding &
Tweaking pages, Ed.) I can
not dispute the novelty of the
approach which is typical of
Elektor. However I guess your
author is using a pretty robust
microcontroller os It's fed with
15 V (!) at its BI part — all at
a supply voltage of 5 V. After
oil, the top of the 33k/33k
voltage divider is held at up
to 30 V.

Peter Zechner (Germany)

UV Light Box
Hi Elektor — just io tell you
that I made a portable UV LED
Light Box sized t OQx 1 60 mm
based on your article in the

3

ekkrn &!ttfreniu - 2 2i a 37

jeroen Hamburg replies:

Thai's right - J er b _ L the part li-
nes including FBI are fitted with
internal ESD protection diodes
These will fa ilh fully conduct vol-
tages higher than about IQ V
(typical) to Vcc. The highest cur-
rent that would occur j"s JO /
33 k — 0.3 mA re., not a pro-
blem 'or tee Oicdes.

Profiler (I )

I d like to know how the
Profiler {January 2007, Ed.)
copes svith milling RGBs.

The Profiler article says
However, based on our
experience it yields excellent
results for average
RGBs"'. I'm unsure
what constitutes
an average
PCB ;r ?

gh-hoie /wired/ components.
Boards rar S.TDs with extreme-
ly thin tracks may pose a pro-
blem and we cannot guarantee
useable results. However we
am convinced some users will
ab/e to construct ond adjust
their Profiler in such a way that
SMD boards con be milled r all
assuming that a spindle motor
with less slack is used.

We would like to emphasise that
Profiler is a multipurpose milling
machine, ijL not specifically de-
signed to mill PCBs , If you want to
mill PCBs only covering anything
from 7970s through-hole right up
to 0402 SAID orsubSGA tracks ,
we would advise buying a speci-
alised (more expensive) mo *
ensue from far example
Colirous,

Solution to Hexadoku December 2006

I

L

2

3

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7

1

B

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6

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8

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3

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[_B_

from Elekfar or Colinbus could
put us right? At the some time
it would be good to hear how
capable this machine is at
turning out RGBs...

'Cruster' and 'Binraker'
(copied/edited from Elektor
Forum)

We are very pleased with all
Forum postings so fop be if cri-
tical sceptical or in praise, as
well as the orders for Profile co-
ming in every day.

We ars preparing a follow-
up to the Profiler
articles already pu-
blished /December
2 DC 6 and January
2QQ7), This may
take the form of an
extensive posting in
the Forum topic or
small (ishi online video

print but the smallest increment
of the stepper motors expressed
in //near travel.

The repeatability of the milling
operations is governed by the
accuracy of the constructor when
adjusting the specific parts men-
tioned in the article for a trade-
off between minimum slack as
o i-oosed to highest accepfabfe
faction. As such the repeatabi-
lity will be of the order of o few
fenfns of a millimetre.

I think it'd be extremely helpful
if Elektor could post their re-
sults so those of us Interested
in using Profiler for RGBs can
see what the machine can do
and arrive at on informed buy-
ing decision. I don't think I'm
being unreasonable asking?
The alternative being having
to spend £ 1 ,099 to find out,
which L'm naturally wary of
doing until I hear more.
'Ouster' (copied/edited
from Elektor Forum)

We confirm that Profiler is soi-
led t c m ' - ' ; n q PC 8s vs r ■ hro u -

Profiler (2)

Mechanical resolution to 10
times the wavelength of red
light? Who makes ihe lead
screws? Thai's a 0.005% er-
ror over 6%

However who: != the repe-
atability and the hysteresis of
the system? Those are equally
important figures.

(--)

Mechanical resolution of
0.0075 mm Is what it says
in the article... unless it s a
misprint? Remaps some one

even a
clip.

We wJ/f certainly revert to the
matter of milling RGBs, which is
perfectly pcs 5 idle using Proffer,
The stated mechanical resolution

of Q.QQ7S t-j-i T- r £ o*it? or mis-

RS232/U5B Stick
with PIC data
Dear jan — ! would like to
copy data supplied by a SAIA
PCD2 PLC system onto your
'USB Stick with ARM and
RS232' (November 2007
Ed.), then plug the stick into
my PC at the end oF the month
and write captured data into an
Excel file. I would think that's
possible using your project. The
PLC data has a different length
all the time: dote 5 bytes; regis-

23007 - sis i t™ eSectranics

INFO & MARKET

MAILBOX

Top-10 Article downloads

From www.elektor-eiectrenics.co.uk

1 . OBD-2 Analyser (7/2005)

2. 5MD Reflow Soldering Oven (1/2006}

3* High-end Power Amp (3/2005)

4- High-End -Preamp, Part I (4/2004)

5, Build Your Own DRM Receiver (3/2004}

6. High-E Fid-Preamps Port 2 (5/2004)

7, Remote Control by Mobile Phone (1 1 /2005)

8. Clarify 2x300W (6/2004)

9, PPP HiFi Valve Power Amplifier (5/2001 )

1 0. ESR / C Tester (9/2005)

ter 4 bytes or 6 bytes,

IF the individual data values
are seaparted ( delimited')
when stored (e.g,, with a com-
ma, would that enable them
to be copied into an Excel
spreadsheet? Or will the stick
only store byte-long data? Do
you know of commands that
enable multiple bytes to be
concatenated back again?

! would like to use VBA for
my purpose. Can you supply
background material for simi-
lar applications?

Alois Schmid halter
(Germany)

Jurgen Engelmann replies: The
USB Stick stores data byte by
by te or, the jVIMQSD card
without inserting delimiters i.ks
commas. However you may sto-
re the data onto the stick in data
ogger mode end take them off
again bier using a VB program
nserr your commas and write
the lot into a second hie.

We do not ha . e the requested
background material sorry .
However it should be possible to
migrate he examples written in
Pascal to VB.

What's that tune?

Dear Jan — 1 heard on
interesting short 'tune' on
the Deutsche Welle (German
world service) shortwave ra-
dio station about 2 years ago
and 1 am intrigued os to what
it is. It is played at regular

intervals of about 10 seconds
in the two minutes leading
up to the hourly news on the
station. Is if used as some kind
of time signal?

The attached .wav file is a
sample of the tune (apologies
for the poor sound quality).
Thanks for your help.
Jonathan Grainger

My colleague Ernst Kt&mpehou er
of Elektods German edito-
rial deportment delved into this
query and set up email con
resp on dence v . tin De u h che
Welle. They kindly replied that
?he ■ one you hoard is a rende-
ring from the opera 'Fidelia by
Beethoven, 2nd Act. See also:
■•vw w. in tervalsignals.org

MoilBox Terms

■ - eaner e

zoiTcscznZer fcs a a;
d - : 1 ? 3 b ter

•Viewports euptessstf by ecffes-
portfarits a w e- r ii “^•cess-arify
(tKJSS dt the Bditef fit Publtsrer
' Cc-'respGndencs may be
frsrtaEsted or edited fortangih
: am..' end sty's
- iYnar. TepSymg :r

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ptaasa av^te issue

ease sand yo-ur MaiJBcx
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EtektorBee: - tea

1 i->CD Great Vest Feed,
B'entfgrd TWO 5HH. tea land.

Corrections & Updates

Sputnik Time Machine
January 2007, p. 42-45, ref, 050018-1

The third sentence under ihe heading 'Schematic diagram'
should be modified to read:

Although these ICs may appear to be standard TTL devices ,
they are specially designed to handle the high voltage level
of Nixie tubes, tike the Nixie tubes , they are not readily
available through * regular commercial channels .

Shortwave Capture
December 2006, p. 24-33, ret, 030417-1
Although the AT90S8515 used in the project is no longer
recommended for new designs,, if is stilt generally avai-
lable (December 2006). A suggested replacement is fhe
ATmega8515 which offers AT9Q58515 compatibility
thanks to its SC851 5 compatibility mode fuse.

Profiler January 2007, p* 14-18, ref. 060232-1
Figure 7 shows an incorrect screendump. The actual pro-
gram included in ihe Profiler kifi has more options for the
design of PCB layouts An example is shown in the screen-
dump printed here.

fc

y.

Tel: 01635 40347 fewbuty FJfKteonics Ltd

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10

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the full package.

Explorer-16 Value Pack £122.90 (€179.00 / US$ 232.50)

(includes DWI-tQOOl, DV164120, AC164125, C30 discount voucher)

Vm'i included

TOTAL £122.90 {€179.00 / US$ 232.50) excl. P&P

Postage and Packaging depends on destination

Assuming you complete and return the C30 discount voucher, the total saving you get through ordering an

Explorer-16 Value Pack may amount to £70 (€100).

Go to: www.elektor-eIectronics.co.uk

Microchip

www.microchip.com

INFO & MARKET

LEDS

~LT

J~L

H,@[DS GODuQ©

Helmuth Lemme

9 ® 9 ®^Etj

The light output that can be obtained using LEDs has increased by four or five orders of
magnitude over the last couple of decades. What is more, LEDs outlast all conventional
light sources. As prices fall, LEDs become attractive in more and more applications.

oue A , 1 1

LEO FA + LED

figure 1 . White LED light can be created
In various ways: (a) a blue LED chip with
a broadband phosphor layer (here yel-
low); (b) a blue chip and a yellow chip;
(<) a UV chip with three phosphors (red,
green and blue); or (d) a red, green and □
blue LED m a single package (a so-called
'RGB' LEO).

Far a long time LEDs, with o typi-
cal operating current of 20 mA,
were used only os indicators or
displays. Thanks fo research cor-
ned out by certain manufactur-
ers our level of understanding

of the physical processes that oc-
cur in semiconductor materials
has risen enormously, and it has
been possible ro build complex
structures that achieve consider-
ably increased levels of efficien-
cy. A modern LED chip contains
more than i us! □ simple pn-junc-
tion: there will be a whole series
of layers of different materials
arranged and doped in various
ways. The results are, literally, a
sight for sore eyes: many modem
LEDs are so powerful that they
dangerous ro look at directly.

Modern LEDs ore based on com-
pound semiconductors in two dis-
tinct families: the phosphides and
the nitrides, Ind i urn-gall ium*alu-
minium phosphide (InGaAlP) cov-
ers the wavelengths From 570 nm
(green) to nearly 1 000 nm (in-
fra red 1, with a forward voltage
drop of 1 .5 V to 2.3 V depend-
ing on the colour. Indium-gallium
nitride (InGaNj devices run from
460 nm (blue) to 528 nm (green)
with a forward voltage droo of
3.2 V to 3.8 V.

Aluminium nitride based devices
can go down to about 200 nm.

which is in the ultra violet part
of the spectrum, with a forward
voltage drop of around 7 V, This
means that practically all colours
or the spectrum, visible and be*
yond, ore available. Using the
second family of materials If
is also possible to moke while
LEDs by adding a phosphor to
the chip fo convert short- wave-
length blue light into a range of
other colours with longer 'wave-
lengths [Figure 1). The light that
appears as white to the eye is
in fact therefore nat always ex-
actly the same colour: a range of
colour temperatures [from cold
white to ‘warm white") con be
produced by changing the rela-
tive amounts of the various spec-
tral components present, jus! os
can be done with fluorescent
lamps Intensive research is still
being carried out into phosphors
and warmer white LEDs with a
higher proportion of red in their
output, are expected to be avail*
able soon.

These are more suitable for light-
ing applications, particularly in
terms of gaming acceptance far
domestic use. So-called RGB

LEDs are olsa available, consist-
ing of one red, one green and
one blue chip in a single pack-
age. The overall colour of the
LED can be changed by adjust-
ing ihe three operating currents
independently: this is a difficult
trick fo copy using an ordinary
light source.

Strides In efficiency

The mam factor in the enormous
increases in brightness achieved
by LEDs over recent years is im-
provement in the electro-optical
conversion efficiency. This quanti-
fy Is measured in lumen per watt
(Im/W). Modern single-colour
LEDs can manage around 65 to
80 Im/W (or more in some cos-
es). while white LEDs manage 32
to 40 Im/W. Fluore scent tubes
are not far ahead, ai between
50 and 80 Im/W. Mains-pow-
ered incandescent bulbs pro-
duce 7 to 10 Im/W, 12 V hal-
ogen bulbs from 15 to 20 fm/
W. For comparison, ihe earliest
LEDs, an the marker in 1 970 or
thereabouts, could manage only
about 0. 1 Im/W.

Figure 2. Designs of high- output LEDs: (a) 'Dragon'; (b) 'Power TGPLED'; (t) 'OSTAS'; (d) 'Muflild'

with three differently-coloured (hips In one package, ».■ ; :.i-

elector sletironis - 2j2B07

When comparing LEDs with fluo-
rescent tubes of apparently sim-
ilar efficiency, il is important to
keep in mind that the latter emit
light essentially equally in all di-
rections. This is suitable tar room
lighting, bur in many applica-
tions a more focussed beam is
wanted, LEDs produce such a
beam naturally, without addi-
tional optics.

Output has also been increased
by raising the operating cur-
rent. The main manufacturers,
Osram Opla Semiconductors
in Regensburg, Germany and
Lumileds (Philips) in San Jose,
Californio offer a wide range
of devices suitable for use at
currents of several hundred mtl-
lEomps; the most powerful are
rated at 1,5 A. The main limit-
ing factor is removing heat from
the device. The chip naturally
becomes very hot and design-
ers hove developed various in-
genious packages to attempt to
provide os low a thermal resist-
ance as possible between chip
and circuit board (Figure 2).
The circuit board is in turn usu-
ally fitted with □ heatsink to dis-
sipate the heat further.

Long-life LEDs

A Further advantage of the LED
is its long life. This is defined as
the time iaken for the brightness
to fall to a given percentage of
its original value, LEDs do not
normolly give up the ghost sud-
denly, but rather degrade gradu-
ally over time. On this point it
is worth noting that some man-
ufacturers use a percentage of
50 whereas others use 70
Using the first definition, mod-
ern LEDs have quoted lifetimes

of up to 100000 hours; in com-
parison, fluorescent lights hove
□n average life of 10000 hours.
Incandescent lamps have even
shorter lives: mains bulbs typi-
cally last 1000 hours, and taw-
voltage halogen bulbs around
3000 hours.

Modern high-outpul LEDs can
therefore replace incandescent
bulbs in many applications. They
have particular economic bene-
fits in situations where changing
the bulb is difficult or expensive,
su ch as in traFfic lights. In many
cars the brake lights use LEDs,
and the first LED headlamps are
expected to appear scan. LEDs
are now widely used in torches
and LED bicycle lights are much
safer and brighter than their in-
candescent cousins, which regu-
larly burn out.

There are many new creative
possibilities open to designers;
LEDs can be installed in spaces
where incandescent lamps would
not be practical because of the
heat they generate (Figure 3),
RGB LEDs can have their colour
controlled by computer, for ex-
ample to change depending on
the time of day.

The latest fad is to use a differ-
ent colour to identify the different
floors o't hotels, offices, car parks
and public buildings. To help the
visitor get his bearings, the col-
our of the lighting inside the lift
changes ro match that of the floor
just before each stop.

££0172 I

The 'P4' from Seoul Semiconductor is, according la the manufacturer, the brightest LED
in Ihe world and can produce more then 240 Im of output ol I L Al 350 mA the effi-
ciency Foodies 100 Im/W* Values of 135 Im/W are expected to he achieved in 2007,

and 145 Im/W by the first quarter of 20QB,

The 'Luxean 111 Star Hex 1 from Lumileds produces up to BO Im in I he white version and
up to 190 Im In orange-red. The heatsink has a characteristic six-painted star shape.

The white 'Platinum DRAGON' from Osrom Opto Semiconductors produces 75 Im at an
operating current of 700 mA; in efficiency terms this is 30 Em/W. The package is similar
in construction and appear acne to the 'Golden DRAGON' high-output LTD from the same
manuf octurer, bul offers double the output power, VTilh □ price of less than ore dollar, the
'Platinum DRAGON' delivers one of the best 'price* toTighl -In tensity* ratios in I he market

Figure 3, LEDs offer many new possibilities !o designers, ^ e*

Web links

Manufacturers (selection):

www„ a va go tec h . co m / 1 ed
www. e o i . co m . tw
www. j i te o n .co m . tw
www* Jumiieds.com
www. o $ ra mo s.com
www* plus opto .co.uk
www.zled.cam
[Seoul Semiconductor)

Distributors (selection):

www. ultra leds.co.uk

www. u k . con ra d . co m

ukdornell.com

www.dollight.de

www.ebv.com

www. led 1 .de/shop

wwwJumitromxxom

2/2007 - e’rbor extremes

13

INFO & MARKET

NEWS & NEW PRODUCTS

Freescale launches RAppID oolBox

To help automotive customers
streamline model-based software
development, Freescale Semicon-
ductor has introduced the gAp-
pID TaatBox a software solution
that supports on-target, rapid
prototyping far Freescole's 32-bit
MFC 5500 automotive microcon-
troller (MCUj family.

The RAppID ToalBox is designed to
help control engineers reduce de-
velopment time and cost when mi-
grating from their application mod-
eling environment to reoi-woHd im-
plementations on automotive MCU
platforms intended for production.
The toolbox provides an ideal pro-
totyping solution for a variety of
automotive applications, such as
engine and transmission control,
anti-lock braking systems and chas-
sis/suspensian systems. Developers
cdso can use the toolbox far non-
auiomotive applications ranging
from avionic systems to industrial
printers to power generators.
Control engineers often validate
their coniral models functionally
by running auto-generated C code
on commercially available rapid
prototyping hardware. However,

the prototyping hardware usually
does not represent the MCU tar-
geted for production. As a result,
the engineers may not know the
control algorithm's actual perfor-
mance on the production MCU, In
addition, engineers prefer to run
Their control algorithms on target
MCUs early in the development cy-
cle to validate their device selec-
tion. However, this can be a dif-
ficult, iimeoansuming task fF they

have to write the initialization de-
vice drivers and scheduler cede by
hand 'which adds to the develop-
ment cycle time*

Freescale s RAppID Toolbox ad-
dresses these challenges by en-
abling engineers to execute their
control models on MPC55CQ MCU
family hardware without writing
code and to profile the execution
of the cade on their target MCU.
Using the profiling feature of the

RAppID Toolbox, application de-
velopers can study the per far*
mance of their control strategy on
the target microcontroller early in
fhe design cycle. The toolbox elimi-
nates the need to invest in expen-
sive prototyping hardware by sup-
porting rapid prototyping on cost-
effective evaluation boards for
MFC 5 5 00 family dev Ices, such os
the MPC5554 MCU. Optimized
DSP blocks enable developers to
take advantage of the single-in-
struction/multiple-data (SIMD ca-
pabilities of the MPC5554.

The Virtual Garage is a Freescale
strategic business unit that provides
software solutions The first RAppID
Toolbox offering for the MPC5554
MCU is available now from Free-
scale's Virtual Garage. Software
support for additional MPC550Q
family devices is planned for the
future.

For more information about the
RAppID ToolBox, visit
www.fteescale,<om/files/pr/vg f hlml.

Smallest DAB radio module

Frontier Silicon has launched what
they claim is the world's smallest
and lowest-cost DAB digital radio
module available today. The new
Capri FS3G i 0, measuring; only 27
x 1 6 x 2.6 mm, is o miniature $MT
(surface mount technology) mod-
ule which enables it to be fixed
directly to the DAB radio system
board and avoids the need for con-
nectors. The small size and high
level of integration in the module
makes Capri idea! for low-power
product applicarions such as liny
pocket DAB players and personal
media MP3 handhelds,, as well as
PDAs and other portable emerloin-
ment devices.

The Capri module is based on
Frontier Silicon s Apalb multi-band
Rr tuner and Kino 2 multistandard
DAB and T-DMB digital baseband
processor. Complete DAB digital
radio systems can be built using
Capri as a slave module controlled
by a host processor, with several
host interfaces available tor control
and data transport streams, includ-

ing SPk SCR,, and 125, The module
receives boih L-Band and Band 3
broadcasts., enabling worldwide
DAB reception.

The Anollo/Kino 2 chipset combi-
nation is based on a highly-inte-

grated system-on-chip architecture,
with the iin dividual chips themselves
contributing to the overall law pow-
er consumption and compact size.
Apollo measures just 5 x 5 x 0.9
mm, making it fhe world's small-

est RF tuner for DAB digital radio
reception, and requires very Few
external components.

Kino 2 measures 10 x 10 x 1.3
mm and integrates multiple periph-
erals and interfaces, which simpli-
fies interfacing to the Rf tuner and
host processor.

Kino 2 executes multiple multime-
dia and communication-based
tasks concurrent with the dec c ding
and error correction of DAB a=_dio
and data streams. It decodes mul-
tiple audio and data services up to
the maximum 1.8 Mbps,

The Capri module is available
now.

Frontier Silicon customers include
Bang & QSutsen, Bush, Dencn
Goodmans Grunaig, JVC, Qn-
kyo, Philips, PURE Digital Roberts
Radio, Samsung, Sharp. Sony and
TEAC. The company has opera-
lions in UK, Ireland, China, South
Korea and Japan.

wwwdranljer-sllkon.tam

14

ebktoF dslrcnrs - 2y 2 G07

See the LITE on temperature monitoring

Lascar Electronics’ EL-
U5B4JTE is claimed to
redefine ihe concept
of o small, low-cost
temperature data
logger. Weighing
in at just 8.5 g and
measuring 68x18
x 9.4mm the EL-U5B-
LITE may he small,
but it delivers the es-
sential features found
on many larger
more expensive dob
loggers.

The EL-USBd'TE meas-
ures ambient temper-
atures from -1 O C to
+50' C at a sample
rate of once every
thirty minutes and
can store over 4,000 readings.
Setup and download or ihe data
logger is simple; plug directly into
an available USB port and open
ihe Windows software ,-. r h ich is

supplied with the data logger.
From here users can assign the
logger name, set high and low
alarm levels., and determine the
logging start time. At any time dur-

ing the lagging period an integral
push button will prompt a bi-col-
our LED to indicate the alarm sta-
tus, Once the study is completed
data is downloaded as □ text hie

this can be grophed
within the supplied
software or exported
to a spreadsheet for
further analysis, A
coin cell is supplied
with the EL-U5B-LITE
and will provide a
bo I ter y life of over
one month s continu-
ous use. The EL-USB-
LITE'S low cost makes
it perfect for applica-
tions such as moni-
toring the tempera-
ture of goods during
shipping or where a
number of loggers
may be required for
a study It is available
immediately from Las-
car Electronics Lid. at
a unit cost of £24.95,

wvAvJascareieEtronks.tam.

■ rTT".; r -'

Good progress in environmentally-friendly lead ree soldering

es that may still be necessary far
the near future has reported that
her team ore now currently mak-
ing and evaluating prototype PCS
assemblies.

An investigation or IMD includes

evaluation of the most popular
brands of leod free solders and
P'CB pad finishes for hone solder-
ing production.

The first botches of lead free FCB
assembly prototypes are being

tested For nn whisker
growth, and are be-
ing compared with
lead-tin soldered
ones. After thoroughly
testing many different
choices of lead tree
as sem bli es. the results
will be compared for
reliability, ease of as-
sembly, quality and
cost.

The lead free pro-
gramme was initiated
early this year as a
Knowledge Transfer
Partnership between
TMD and CRDM Re-
search (Centre for
Rapid Design & Man-
ufacture) a Deport-
ment of the Faculty of
Technology Bucking-
hamshire Chiltern Uni-
versity College The
pregramme is funded
by the Department of Trade and
Industry and TMD.

www4md.co.uk

D“026-v i

TMD Technologies
ltd. nos mode signif-
icant advances in its
programme to investi-
gate ihe implications
of new legislation re-
lated to environmen-
tally-friendly lead
free soldering proc-
esses in the manufac-
ture of its microwave
transmitters and as-
sc-dated products.

The lead-free pro-
gramme is aimed at
meeting the require-
ments of new green
EU legislation, which
came Into force in
July 2006. The legis-
lation restricts the use
of o number of haz-
ardous substances
(RoHS),

Dr Shubo Goo, who was appoint-
ed last year with the responsibility
far ensuring that TMD s Future PCB
assembly processes will be com-
patible pvitft not only lead free but
also any lead containing process-

2/2007 - elsktor eltri ionics

INFO & MARKET

NEWS & NEW PRODUCTS

Sensorless motor control platform

International Rectifier introduced a
sensorless sinusoidal motor control
platform that delivers quieter oper-
ation and higher efficiency for vari-
able-speed pump applications up
lo 300 W. By effectively can I rol-
ling pump operation over a wide
range of flow requirements, vari-
able’ speed pumps can cut energy
consumption by up lo 50 percent.
The latest iMOTlON _v integrat-
ed design platform consists of a
mixed-signal controller the IRM-
CF371 , and companion intelligent
power module far the power stage.,
as well as algorithms,, development
software and design tools.

The IRMCF371 mixed-signal con-
trol 1C for pumps integrates all fhe
control and analogue interface
functions required for sensorless
sinusoidal control of permanent
magnet synchronous motors (RMS)
using DC link current measure-
ments. Analogue functions on the
1C include differential amplifier,
dual sample and hold circuits, and

a 12-bit A/D converter to sample
the low-voltage signal across the
DC link shunt. The IRMCF371 in-
corporates IR s patented Motion
Control Engine [MCETM], an algo-
rithm editor that eliminates coding.
An integrated 60 MIPS 8-bit, 8051
microcontroller enables application
la ye r softwa re d eve bpmenl, ope ra ti

ing independently from the MCE,
and does not compete For system
resources such as interrupts or inter-
nal registers. The embedded Ana
Ic-gue Signol Engine [A5E™| inte-
grates oil the signal conditioning
and conversion circuits required
for single current shunt sensorless
control of a RMS motor.

The IRAMS06UP6GB is □ compact,
Intelligent power module optimized
lor electronic motor control in ap-
pliance applications that features a
three-phase Inverter with SC driver in
o compact single in-line (SIP 1 1 pack-
age. The device includes a shutdown
function and over-current protection
for safe operation. Other built-in func-
tions include current feedback via
dedicated internal shunt resistors and
a temperature sensing derice.
Design tools include communi-
cations software runnino on the
8051 microcontroller that gives
the PC -based MCEDesigner 1 ’ 1 ' soft-
ware access to the cantrol param-
eters and system variables in the
shared memory. This allows modi-
fication of the controller set points
and control loop gains and other
constants without needing to mod-
ify or compile software.

www.irf.com/produttdnfd/iraoljon/

" " --0H

50Q RF switch for DC - 6 GHz

Peregrine Semiconductor, an-
nounced availability of the RoHS-
compliant PE42555 5 OChm sw itch
for high-performance broadband RF
applications such os cellular infra-
structure, WiMAX and high-preci-
sion RF applications. Manufactured
on Peregrine's revolutionary HoRP 7 '*-
e n hanced U 1 !raO\ \GS’ v fecbn a! ogy,
the Single-Pole, Double-Throw (SPOT]
device operates with exceptional lin-
earity From DC to 6.0 GHz. pushing
fhe upper limits for broadband per-
form once past standard competitive
devices. A proprietary design fea-
ture enables the device to eliminate
the phase and insertion loss drift that
occurs after a switching event, mak-
ing trie PE42555 the industry's fast-
est 5PDT RF switch to reach a fully
settled state.

like all UitraCMOS HaRP-enhanced
devices, the PE42555 features ul-
tra fas! settling time, which allows
systems to respond faster without

a reduction in RF performance. A
typical GaAs-based switch has □
well-known gate tag in settling lime
which Is not usually defined in its

operational specification. This tag,
which develops a phase and inser-
tion loss drift; is nonexistent on the
Ultra CMOS-ba s ed PE42555.

The device also delivers low inser-
tion loss (0.65 dB £ 3.5 GHz and
0,90 dB @ 6 GHz!; high IIP3 {>50
dBm DC-6 GHz); PldB compres-
sion point of 34 dBm [DC -6 GHz) :
and high isolation (27 dB § 3,5
GHz and 21 dB @ 6.0 GHz).

The PE42555 is available in the
4x4mm 20-lead GFN package.
Volume production ore available
now through Peregrine's global
sales representatives and its world-
wide distribution partner, Richard-
son Electronics,

www.reiltom * www.psemi.com

V

Wireless electrical sub-metering components

LEM launches the W E-LEM (W ire-
lass Local Energy Meter) family
of components, an innovative so-
lution that allows electricity con-
sumption to be monitored and re-
duced. By using wireless commu-
nication, VVi-LEM greatly reduces
the time, cost and disruption in-

volved in deploying a sub-mefer-
ing installation, increasing both
the potential Financial savings
and removing many of the barri-
ers to adopt this proven approach
to reduce energy consumption.
The WMJrM family consists of:

* Energy Meter Nodes - an assem-

bly of ) to 3 current transducers
with its signal processing module.
They con be deployed to measure
energy consumption at any paint
in the power cabinet and transmit
the data.

* Mesh Nodes - o repeater linking
various Nodes, They enable 'wire-

less comrrmn Italians throughout o
large installation;

• Me s h Go te- a gateway mcnagi ng
the mesh network. It provides data
through serial interface to a PC.

By measuring active, reactive and
apparent energy plus maximum

eleklor dert rente - 2 - 1 2QG7

current and minimum voltage, En-
ergy Meter Nodes provide much
mare information than a simple
sub- meter,

A variety of Energy Meter Nodes
- all of which have their accuracy
certified to IEC 62053 Active "Erv
eray Class 1 and Reactive Energy
Class 3 - are available for 1 20
and 240 VAC voltage one con-
figured for nominal currents from
5 to 10OA. The compact sized,
split-core transducers can easily
be installed inside the limited free
space of existing cabinets. Energy
Me:er Nodes take measurements
at 5 to 30 minute intervals and
transmit the results over the 2.4
GHz ISM band., The technologies
make installation and commission-
ing very easy.

Mesh Nodes act os repeaters, and out any need for additional can-
can be added to the network with- figuration or programming.

The Mesh Gate Is a stand-alone
wireless network management
gateway that connects the trans-
ducer network with a PC using a
serial interfaces PS-232 or RS-485
with a MODBUS RTU protocol.
Each Mesh Gale allows monitor-
ing of up to 240 Energy Meier
Nodes, The 802.15,4 communica-
tion standard has □ proven robust-
ness in industrial and commercial
environments.

Mesh Gate and Mesh Nodes
were developed in close coopera-
tion by Millennial Net, leader in
Wireless Sensor Mesh Network
technology.

wwwJerruoni

:Q’7G2£-.

ZigBee 1 ' 1 protocol platform with 2.4GHz IEEE 802.15.4 transceiver and net

mg and automation and personal

Microchip announces three new
offerings for wireless networking
— the MRF24J40 Iransceiver,
the MiWi™ protocol stack, and
the ZENA 7 "' 1 wireless network
analyzer.

The MRF24J40 is Micro-
chip's first RF transceiver. It is a
2.4GHz IEEE 802.15,4 trons*
ceiver for ZigBee 7 ' 1 ' and other
proprietary wireless protocols
in applications requiring tow
power and excellent RF perfor-
mance, with very few external
components. The device exceeds
all standard IEEE 802.15.4
specifications, and provides Full
Media Access Controller (MAC)
support and an Advanced En-
cryption Standard [AES] hard-
ware encryption engine.

The MRF24J40 IEEE 302.15.4
transceiver is packaged in a
40pin PbTree/RcHS-compli-
□nf 6x6mm QFN package. It is
sampling now.

Microchip currently offers the
only fully- featured ZigBee proto-
col stack with a free of charge li-
cense and no royalty fees, which
is also one or the smallest in the
industry and provides a source^
code format that allows design-
ers to customize their product
usings broad portfolio of PIGI
microcontrollers.

However, since the full ZigBee
protocol has now grown too
large and complex far many ap-
plications a large percentage

of the market for IEEE 802,15.4
vdretess networking is likely to use
alternative, proprietary protocols.
In addition, ZigBee protocol cer-
tification is a costly and cumber-
some process.

Microchip's MlWi protocol is a
free, small-footprint protocol de-
veloped for customers who do not
need Full ZigBee protocol interop-
erability but wont to use standard
IEEE 802. 15.4 transceivers in low-
cost peer-to-peer, star and mesh
networks. No certification is re-
quired for MiWi protocol systems,
and the protocol stack is provided
under a free license if used with
Microchip's microcontrollers and
the MRF24J40 transceiver.

The new ZINA wireless net-
work analyzer tool [part num-
ber DM183023) uses a simple
graphical interface to configure the
free Microchip ZigBee and MiWi
protocol stacks. This can reduce the
code size by removing optional fea-

tures; con cut development time by
simplifying the interactions with the
stacks; and can allow customiza-
tion cf the stack to fit a particular
need. Consisting of both hardware
and software, the ZEN A wireless
network analyzer that is capable
of decoding IEEE 802.15,4 Zig-
Bee ond MiWi protocol pockets
— from the lowest layers to the top
of the slack (including the security
modules). The network-configura-
tion display window allows users
to see the traffic in real lime, as it
travels from one node to another. A
session can also be saved to a File,
to allow further analysis of alt the
network traffic.

Regardless of which protocol a de-
sign engineer selects. Microchip s
complete solution enables them to
rapidly evaluate and begin devel-
oping a vast array of wirelessly
networked IEEE 802.15.4 appli-
cations, including security lighting,
access control, industrial monitor-

compuler peripherals.

In addition to rhe ZENA protocol
analyzer, Microchip offers the PIC*
DEM™ Z 2A GHz Demonstra-
tion Kit (part number DM163027-
4], which is on easy-to-use evalua-
tion ond devebpmenl platform far
IEEE 802,15.4 application design-
ers. The kit Includes all of the hard-
ware, software source code and
printed circuit board (RGB) layout
files needed to rapidly prototype
wireless products. A detailed ap-
plication note is also available on
Microchip's website. This devebp-
menl platform is based on Micro-
chip's PIC 18 high-performance mi-
crocontroller family offering a wide
selection of products with up to
1 28 k Bytes cf Flash program mem-
ory in 28- to 1 OO^pin packages.

For additional information, visit Mi-
crochip s Web site at

www. micro thip. tom /zigtae*

lurroze-i t

2 y 2007 - suitor detfrenits

17

TECHNOLOGY

TELEMETRY

_ „_J"T _ . . Jt _

'

Michael Naderhirn and Benjamin Hack)

As processors become ever more powerful we
tire witnessing the rise of more 'intelligent'
systems. We now look to sophisticated robots
to assist or even replace us in difficult or
hazardous environments. This is particularly
true of military hardware where we have
seen on our TV screens the use of unmanned
aircraft and vehicles in some recent conflicts.
The basic idea however is not so new; we
take a look into the world of 'drones'...

The history of remotely controlled aircraft can be traced back
at feast to 1 935 when the aircraft manufacturer De Havilland
installed a radio conirol receiver in the passenger seat of a
iiger moth biplane (christened the Queen Bee' [] j) For use in
gunnery target practice. The bee analogy was maintained
when unmanned aircraft were then given the name drones'.

In the intervening 70 years the unrelenting drive for electronic
devices to become smaller, faster and cheaper has led to
the development of small artificial insects and also to flying
robots' with control systems capable of piloting an aircraft
autonomously. Falling costs and the availability of Increasingly
powerful processors means that enthusiastic amateurs and stu-
dent groups have also been able to make contributions to the
Field of autonomous aircraft and helicopters*

UAV classification

Drones are categorised according to their size and pur-
pose, Collec lively they are known as Unmanned Aerial

Vehicles (UAVs). Military versions of these aircraft basi-
cally fall into one of iwo categories; ihey can be passive;
gathering intelligence, making radio intercepts and video
reconnaissance or as Unmanned Combat Aerial Vehicles
(UCAV) they can be fitted with weaponry enabling them
to rake pari in offensive strikes.

The UAV is further classified by the method which if
achieves flight; If can be classed as a fixed wing r a rotat-
ing wing or an ornilhopter (flapping like a bird). Un-
manned balloons and airships are lighter than air and
are not classed as drones.

A further distinction is mode with reference la the level of
autonomy of which ihe UAV operates. At Its simplest level
the aircraft is controlled remotely via a radio link, the next
level of complexity provides the aircraft wilh same degree
of self-control (autopilot function). The most sophisticated
aircraft receive GPS posifianoi information and con Follow

18

efeklDr riEdroniis - 2/200?

a flight plan using preprogrammed waypoints, sensors
detect obstacles and there is sufficient on-board com-
puting power to calculate an avoidance strategy while
maintaining aircraft stability. An ongoing research topic
involves the development of control algorithms enabling a
group [swarm) oF UAVs to collaborate on a task.

The most important classification however relates to the
size of the craft:

Micro UAV

These drones can be operated by one person (Figure
I). In principle every average-sized model aircraft is a
Micro-UAV. They are typically powered by either interna!
combustion or electric motors [Figure 2), The availability
of relatively low-casl modelling components including sen-
sors (gyroscopes and accelerometers) coupled to micro-
processors enable rat&of-fum and acceleration values to
be measured and an inertial guidance control system to
be produced quite cheaply. On these grounds the Micro
UAV is an attractive development platform for a small de-
sign team who could expect to produce □ vehicle with a
number of commercial applications at a reasonable cost.

Mini UAV

As you might expect this class of drone is bigger than the
micro UAV and requires a larger team of operators on the
ground. The Luna system (Figure 3) produced by EMT
is one example of this type of drone which has been used
by the German army for a number of years most recently
seeing service in both Afghanistan and the Balkans. The
Luna has a reconnaissance speed or 70 km/h with a
maximum altitude of 3 500 itl li con stay aloFt far around
four hours carrying a payload of up to 4 kg .

MALE /HALE

MALE (Aledium Altitude Long Endurance} is a category of
UAV capable of long duration flights and operating Qt an
altitude of 10 to 15 km. HALE [High Altitude Lang Endur-
ance) can operate for a similar lime but at an altitude of
around 20 km. Both of these are clossed os large UAVs
and can remain airborne tor up ia two days. Two of the
most recognisable UAVs in this category are the Preda-
tor (MALE] and the Global Hawk (HALE) both operated
by the US air force. The 1020 kg Predator (Figure 4) is
powered by an Austrian Rot ox-Mot or developing around
100 hp hrough a pusher p^petler which gives it a top
speed o' approximately 1 3 ri m/h at an oltilude of 7600
m, It he n operational rac n the order of 640 km
carrying 200 kg load A mo> e recent version of the
predator can be used as a UCAV, A long range variant is
powered by a 130 hp German Thielert diesel [2] which is
based upon the 1 .7 litre engine used in the Mercedes A-
doss vehicles. The Global Hawk (Figure 5) uses a Rolls-
Royce gas :jrbine giving It a top speed of around 600
km/h at an altitude of around 20,000 m. The craft has o
global range of 26,000 km with on all-up weight of 1 2
Tonnes. It can r cmaln airborne for two days carrying a
payload r' ‘ JO kg.

LICAV

The development of armed UCAVs for military use is cur-
rently a very active field of research and development.
Preliminary performance figures of the X-45 currently un-
der development by Boeing indicate that it has a maxi-
mum speed of Mach 0.85, service altitude of 1 2,000 m,
an operational radius of 2000 km with a maximum pay-
load of 200 kg. The UCAV shown on the title page is a
prototype craft by the French company Dassault.

Pspsrszzi equipped
Modet Aircraft

Sferty art
RC TfEr^Ti'ttcr

Radkhttodem

Ground Station

Figure L

The J Q peci-source UAV f
ground stall on consists of a
laptop with a radio modem
for communication end o
Stoddard PC Irani ml Iter
lor autopilot bo i hip.

Figure 2.

[he 'Carolo' is a typical
example t f a mitre UAV
using model aircraft
components.

Figure 3.

The German
reconnaissance vehicle
LUNA has been in service
with the German mi I Han
since 2003.

Figure 4.

The General Atomics
Tre-dalor 1 is probably the
mosl rexognlwblE middle
category (MALE) drone.

2/200 7 - elektsr electron irs

19

TELEMETRY

Figure 5.
The long endurance
feccnnaitfcnce
Glahal HcaL

Figure 6,
The rtiucturc of o UAV-
flight control r/ilem.

navigation

fas* overview

obstacle

rtcognilicn

coniro

sensor

array

&6CtE3 -1£

Figure 7.
Automatic oircroft central
requires Information from
oil three axsi.

r nn

mm ■ n

Figure B.
gyroscope evaluation
d from Analog devices
ilco ideal lor your own
UAV project.

AUK AUX
ADC BAC 'Jru

cs

SC LX
CeN

dwt

Flight control

The scope oF this discussion will be limited to fixed-wing
drones; they present fewer technical challenges and are
by Far the commonest type. Figure 6 shows the structure
or a typical flight control system. In a manned aircraFi the
Dilot steers and controls the aircraft but with a UAV the pl-
ot is replaced with a control loop, sensors and actuators
to steer the UAV.

In order to maintain aircraft stability it is necessary For the
control software to have information from sensors giving
the craft's current situation. The following values are there-
fore important;

- Position (geographical coordinates and altitude]

- Speed in a three planes [forwards, sideways and

altitude). . .

- Euler angle [Rotation around all three axes; pitch, yaw
and roll Figure 7)

The aircraft’s status can also be described using airspeed,
angle of incidence and sideslip angle.

There are o number of different sensors available to meas-
ure these values. The Paparazzi UAV [3] uses o low-cost
two-axis infrared thermometer for attitude determina-
tion while geographical coordinates are given by a GPS
receiver. Altitude is provided by an absoluie pressure
sensor while raie-of-climb is measured by a dynamic air
pressure sensor. The sensor readings are then scaled and
converted info meaningful values in the navigation filter
software.

The greater the processing power the more sensors can
be used, it also allows more complicated filter algorithms
to be applied to the sensor dato. Additional systems
can also be integrated with ihe motion sensors already
described for exomple an inertial gyroscope can also
provide motion information. When this additional sen-
sor data is correctly interpreted with the existing data it
will give a more complete picture of the craFts behaviour.
This process known os 'sensor fusion mimics the process
occurring in the brain when you view two pictures taken
by a 3D camera from slightly different positions. Both im-
ages are [usl two dimensional but when the left and right
pictures are viewed by the corresponding eye your brain
is immediately able to extract depth information from
the images. In the navigation system accelerometers are
used together with gyroscopes to give angular velocity
information.

Figure 8 shows a gyroscope module evaluation board
from Analog Devices [4]. The filter algorithm used in this
device is also know as a Kalman Filter, (n comparison to
simpler filtering techniques Kalman filtering requires the
use of a powerful processor [by current day standards).
The desired values ore the pre-programmed waypoints
defining the flight path. These waypoints can be pro-
grammed into the on-board navigation computer at the
ground station before the flight begins or during flight
over o radio link. Alternatively they can be generated au-
tomatically by a higher level control loop known as a tra-
jectory planner; this represents a more sophisticated level
of vehicular autonomy.

The topics of automatic trajectory planning, collision
avoidance and coordination of groups (swarms) of auton-
omous UAVs are currently hot topics at numerous research
institutes and universities.

20

dstow atedronUs - 2/2057

The

Record

hook

The first UAV to cross the north
Atlantic non stop was manu-
factured by the Australian
company Aeroscnde, The right
was made in August 1 998 by
she 13 kg twin-boom croft with
a 2.9 m wing span carrying 7 1
of fuel. It took almost 27 hours
to Fly the 3270 km course from
Newfoundland to Scotland.

The 20 cc 4 -stroke Enya mo-
tor required just 5/7 litres of
petrol to go the distance which
works out at about 570 km per
litre of on overage speed of 1 20 km/h. This particular drone
is designed to gather metrological data; ils rear mounted
"pusher 1 prop allows the nose core to be fitted 'with instru-
ments where they are free from propeller wash.

Five years after this event in August 2003 a much smaller
model aircraft named TAM 5, built by the model aircraft
enthusiast Maynard Hill set an FAl record by making the
3000 km journey from Newfoundland to Ireland in 38 hr
and 52 mins. Like the Aerosonde, conventional remote con-
trol was used for take-off and landing but ihe rest of the
journey was controlled by on on-board oulopilot using GPS
positional data. The 5 kg balso model has a wing span af
1*8 m ond uses □ modified 10 cc 4-stroke OS motor, it used
oil but ICO ml of its 3.3 I of fuel ra make ihe crossing giving
it a fuel economy figure of 1000 km per litre!

The altitude record sei in August 2001 Is held by Helios, o
/5 m span electrically powered UAV which was developed
by the Californian company AeroVironment in collabora-
tion w ith NASA. The 580 kg croft flew to a height of 29,4 1 3
meters (about three times Ihe height of a typical commercial
flight!) driven by 14 solar-powered electric motors.

The largest unmanned aircraft at 1 06 ronnes was a convert-
ed Boeing 720 operated by NASA. tEs find! test manoeuvre

Brain power

One or two ATmego processors usually provide sufficient
processing power for a simple micro UAV bul as system
complexity increases For example with the use af Kalman
filtering the addition of DSPs become essential. With more
vehicle autonomy the necessity to process video Informa-
tion and data from additional sensors in real-time dictates
that FPGAs and highly specialised DSPs need to be inte-
grated into the vehicle's control system.

Payload

The on board sensors usually lake up the majority of the
available payload in the UAV. The types of sensors fitted
depend largely on ihe size of ihe UAV. Mikro-UAVs ore
most commonly fitted with cameras operating in ihe vis-
ible and !R part of the spectrum. Reconnaissance drones
usually carry high-resolution and thermal Imaging cam-

carried out in Decumh^r 198- (controlled impact demonstra-
tion! was designed to test the effectiveness of a fuel additive
during crash landing.

The December 2006 issue of New Scientist reported □ tsst
recently conducted on a SAC 1 1 1 airliner fitted with a UAV
control interface to assess pilot workload while controlling a
simulated: swarm g; UAV 5 in a battle siiuaiion. Pilots were on
hand to perform the take-off one landing.

Web Links

www.aer 0 de 5 Egri.de ■ aeter 1 999 Aerosonde- Ac-rosonde.html
wvav. ae roso n de . co m ■■ r d r a w a rt Ic ! e ■' '4

www. a a ♦ wa 5 hingi 0 n.edu/ res ea rob , ' a ero sonde, la I ma . hi m
w ww.mf c- os n ab rueck . co m / TAA V5.htm
tom. planned 1 .com-’

ww -v, d Tc.no so. go v News ra 0 m X Press s tort es ■' 05 08 0 2 r e s_
recardJxf.html

ww w.df rc.naso.go./galle ry me v E e C ! D/ 1 n dex , htm ;

■ 1 -. v/ w, n e w sc i e nl i sfteth . c o m a rt l cl e . d n 1 06 7 5

eras for use in darkness and conditions of low visibility.
Larger UAVs like the MQ-1 Predator ore also fitted with
conventional radar or SAR (Synthetic Aperture Radar).
With the addition of anti-tank rockets Inis particular drone
can be configured as a UCAV. The UAV payload can also
consist of communications equipment to provide a radio-
relay function, thereby extending the range of battlefield
communications in difficult terrain. Fitted with ECM [Elec-
tronic Counter Measures) equipment the drone can also
play a role In the so-called electronic warfare" where it
con actively disrupt communication systems or identify the
source of unwanted jamming signals.

The number of commercial applications for drones is also
growing and they have been used for forestry surveillance
and traffic monitoring. The number of internet sites devot-
ed to this subject is evidence that the goal of producing a
truly autonomous aircraft or helicopter is very appealing
to many model Fliers with electronics backgrounds.

M007 - ebktar elgrirunia

21

TELEMETRY

Figure 9.
Screen capture of a
Poparani flight [3] during
\K= 2003 Supaero conies! .

Quod in Karlsruhe [8]. The University of Delft in Hol-
land has an ornithopter project Delfly' [9] while 'VVI7AS
[10] is a helicopter UAV from the linkaping University in
Sweden [based on a commercial RMAX mini helicopter
from Yamaha [11]) and of course the Paparazzi project
in France.

D1YUAV?

Anyone fired up sufficiently to start work on their own
UAV can make o good start by browsing the pages of the
open-source projects described on the internet [3] [72]..
The hardware designs ore available in Eagle or target file
format. Software for the paparazzi project is a compiled
Linux distribution containing all the necessary files. Those
of you who cannot wait to gel their own project off the
ground could of course splash out on one of the systems
offered by the US companies MicroPilot [13] or UNAV
[14] these ready-made auto pilot solutions are available
in a number of different versions offering varying degrees
of control sophistication but expect to pay somewhere in
the five-figure (dollar) region for the most complex, Fully-
feotured system.

Projects and Competitions

A quick trawl of the internet identifies several interesting
open-source projects with a UAV theme. The most widely
known is probably the Paparazzi' project [3] which be-
gan life at ihe ENAC in Taulause and has been running
For a number of years. In the process of development a
small PCB fitted with ATmegas has been designed.

In Europe there are a number of competitions and con-
ferences where researchers and design engineers meet,
show off their latest designs to the public and generally
exchange ideas. The European Micro Air Vehicle Confer-
ence and Competition [EMAV 2006) included a chal-
lenge v/iih the aim to find the smallest autonomous aircraft
able to most quickly fly a route using pre-programmed
waypoints and finally to recognise a high-contrast symbol
marked on the ground. It was impressive to see just how
many of the entrants were able to complete the tasks. This
year will see the third annual meeting of the "US-Europe-
an Competition and Workshop on Micro Air Vehicles' [5]
held in Toulouse from the 18™ to the 21 sf of September.
There are also several small aircraft and helicopter UAV
projects currently under development in some German
universities for example the 'Carolo in Braunschweig
[6], the MAY series in Aachen [7] and the four rotor Air

m ViW ja a pt ee u we n . c ft m vav? a r rc ro ft

(2j hflp://v/eb.tftislert.com/typo3/index.php?Id— 5 1 4&L=1

1 3 . w ,v. r- ong nu.o rg ■■■ p a p a r o zzi

[4] www> a no I og.com / U pi o a d ed Fi les/Eva I uatio n J&oo rds Touts/
1 70491 61 4ADJ51 6250 PCBZ.pdf

1 5 ] v.\w.\ mcr.Q7.org

[ 6 ] « pVAvnlr mgiu -bs.de * for setiung ! mcv

17 j http: //wvAv.dynamjk.rwth^a pchen.de/ mo v/

|BJ vwAv.pr^Ese.un i-karlsruh e .d e/ 6 4 00 *ph p

[9] http://v/vAv.tudelftm!/live/binaries/5bo8080d-633 1 -49cb-
9d 68 - 6 5 8e4 50299 f9/d oc/DO 05 -4- 1 microp! ane.pdF

[ 1 0J www. ida.liu. se7 ~m a vtnj pope rs/l CAP506_Systsm_Dem o.
pdf

[1 1 1 www, yamaha^motor. co .j p/g I oho I/in d ustna l/sky/i nd ex btml
H 2; iwvw. a I bn r ro is - u a v. a ra
[1 3. .■Av.v^rnicropjlot.ccm
[14] www. u - n a v. go m

figure ID.
ko main purls cl ihe
Albatross project [12] by
John Stowers and Hugo
Vincent Ircm Hew ZeafornL
Micro -UAV (left) and main
board lilted with an ARM
centre I lilt (right),

22

dektor electronics - 2 2007

ronix m

_

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TECHNOLOGY

r

Mike Bessant

Model construction as a pastime flourishes alljoypjgH^ world, attracting
people with an interest in replicating vehicles immmiature. Including
rockets — fully functional and complete. And y/jS^rally like to see all
sorts of flight data (telemetry) too. But WpyralkM get hold of this data,
when the rocket is soaring off at an altitifa^OTSOO m or more? A cable

is not an option. This circuit nevertheles
Telemetry is taking off, literally!

ows you how to do this.

F'tjuie I. Block diagram of I he air borne (hopefully skiborne!] telemetry SjSlem.

flies with the rocket is contained on urometer, gyroscope, barometer, Hall-

The amateur rocket building commu-
nity in Europe grows at a steady pace.
According to a US agreement there is
a distinction between two separate
groups: those that occupy themselves
with model rockets and those that
work with high power engines. The
vast majority of launchings fall in the
category of model rockets. That is be-
cause high powers demand stringent
safety requirements and relatively ex-
pensive materials,

A standard model rocket vehicle kit
can be found in hobby shops from
about £ 25, including the disposable
engine. More advanced models that
use a cluster engine to lift a usable car-
go (‘payload 1 in space terms) hundreds
of meters or even a few kilometres into
the sky can stimulate electronics en-
thusiasts with all kinds of interesting
challenges, -Applications range from
aviation technology to environmental
monitoring.

On boord

An example of a payload is described
here. The system can transfer informa-
tion from the sensors wirelessly to a
ground station. The starting point is
a real-time video link. Aside from the
high entertainment value of on-board
video images, they also contain useful
information regarding various flight
data such as rotation speed, highest
point, rime instant of parachute de-
ployment* etcetera. This data can also
be related to data from other sensors
that are on also board.

The audio channel of the video link
proved to be eminently suitable to send
the sensor data. The result was better
than that obtained from using a sepa-
rate transmitter. The audio and video
signals are received on the ground and
stored on a portable video recorder or
a camcorder for further analysis on a
PC. Data storage on board of the rock-
et is also a possibility of course, but if
something goes wrong you would re-
ally like to be able to access this data.
It is usually the case that those rock-
ets that have something wrong with
them are the ones that end in fire-
works, at which point the data stored
on board cannot be rescued any more.
A second advantage of using a trans-
mitter is that the rocket can be easily
found after landing, using a directional
antenna.

Figure 1 shows the block diagram of
tile telemetry system. The pari that

one circuit board that fits in a stand-
ard 6 cm model rocket tube. One side
of the -Airborne Video Telemetry (AV-T)
board is fitted with the telemetry com-
ponents, while the other side contains
the camera and transmitter module
(see Figure 2).

The AV-T board has a versatile sen-
sor port and can be configured for a
large number of analogue and digital
sensors using the BASIC programming
language. The sensors and their sig-
nal conditioning electronics are fitted
on several stackable primed circuit
boards that are interconnected with
a ribbon cable. Figure 2 shows that
the sensor boards are perpendicular
to the main circuit board, in this way
sensors such as accelerometers and
gyroscopes are correctly aligned with
the longitudinal axis of the rocket. A
typical payload would consist of one
or more of the following sensors: accel-

sensor and GPS receiver.

Picture

Tire selection of a usable camera is de-
termined by working backwards from
the video standard of the recording
system on the ground. We have as-
sumed a PAL TV system, but die prin-
ciple is the same for other standards.
There is now a large choice of mini-
ature full-colour cameras that can be
bought for less than £ 75. Cameras
based on CMOS technology are usu-
ally cheaper, use less energy, but are
generally not as good as their GCD
counterparts.

During the flight the camera is subject-
ed to continually changing light con-
ditions. The rocket rotates around its
axis and turns around at the highest
point. In order to get pictures of rea-
sonable quality it is best to choose a
camera that is fitted with automatic

antenna 2_4 GHz transmitter cam-era wiTwkrw battery

\ \ r <

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ribbon
* cable

ptaMlc mae cone

y AV-T beard sensor stack card

.z-JLl ,1 tl

figure ?, Cutaway view of I he payload, showing on example of construction inside the racket

2-2007 ■ sJdfor Erodes

25

TECHNOLOGY

ROCKETRY

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gain control (AGC), electronic shutter
speed (AES), white balance (AWB) and
backlight compensation (BLC),

A standard PAL TV camera including the
lens will easily ht in a cube with 3 cm
sides. The weight viriH he about 10 grams
and the camera will be happy with
bO mA at 12 V The standard resolution
amounts to 3 SO TV lines and the output
is typically 1 into 75 Q. Tlnee wires
suffice to. connect the camera: power
supply, video -output and ground.

Transmitter and antenna

An easy way to transmit live video over
a few hundred meters (vertically) is to

use cheap transmitter and receiver
modules intended for consumer appli-
cations such as security cameras and
TV video links. Most of these modules
use the Industrial, Scientific and Medi-
cal (ISM) band at 2.4 GHz. A standard
video transmit module weighs about
15 g and has dimensions of about
1x3x4 cm. The current consumption
of the module is also around 50 mA at
12 V The output will be in the region
of 10 mW into 50 Q via an SMA con-
nector. Four signal wires are gener-
ally enough: {video and audio inputs,
power and ground}. If the camera and
transmitter module use the same vid-
eo standard then the output of the first

can be directly connected to the Input
of the second.

Rules

National organisations such as OfCom
and DTI in the UK, or FCC m the US,
look after the rules for the ISM bands,
so that only products that comply with
these rules are permitted. These rules
vary from country to country and it is
the responsibility of the user to use only
equipment that complies with the re-
quirements of the country it is used in.
An example of a restriction is that the
antenna in the ISM band is not allowed
to nave any significant gam. So an om-

26

dehor dsttrcni^ - 2f20D7

nidirectional antenna has to be used.
This type of antenna radiates the same
amount of energy in all directions. For-
tunately this is just what we need for
this application. Omni directional VaK
whip antennas that fit directly to an
SMA connector are readily available.
It is Ideal if the antenna can be fitted
in the plastic nose cone of die rocket,
located as far as is possible from the
circuit board, the batteries and other
metal objects.

AV-T board

Figure 3 shows the schematic of the
A \ rfa o me -Vid e o -Telemet r y-s y s tem . The
circuit uses a PTC AXE microcontroller
(ICS), The PICAXE family consists of
PIC Flash microcontrollers from Micro-
chip which are pre-programmed by a
company called Revolution Education
Ltd (REL) with bootstrap code. With
this code, the PICAXE microcontroller
can be repeatedly programmed in BA-
SIC with a simple 3-wire connection
to the serial port of a PC. In this way
a conventional In -Circuit -Programmer
(ICP) is not necessary.

The PICAXE family comprises 8, 18, 28
and 40-pin versions that REL sells for
about the same price as that of a one-
off unpro gramme d PIC,

The AV-T uses a FICAXE-18X (the
bootstrap code indicates that it Is a
PIG16F88). In addition to the stand-
ard general-purpose I/O-lines, the IC
contains three 10 -bit ADCs, an I 2 C bus
and a UART port. The AV-T has a se-
rial port to support the ICP and soft-
ware development with the PICAXE
Programming Editor fl]. This Win-
dows p ogram has a version of BASIC
that sir oorts many spec 7 „ interface
comma Is (readade, coi n pwmoui f
readme This greatly simplifies

the development of the software and
the testing of the sensors. The inter-
nal PICAXE clock can be programmed
to run at either 4 or 8 MHz. This corre-
sponds to about 10 k or 20 k BASIC in-
structions per second. The non-volatile
memory of the PICAXE can hold about
600 lines * BASIC code.

The FXul4 (IC5) is an FSK-modem (Fre-
quency Shift Key) that has been de-
signed for communications using asyn-
chronous data at a speed of 1200 bps
(bits per second). In the transmit mode,
which is controlled by the AV-T t two
discrete frequencies are produced at
the output. These depend on the lev-
el of the logic signal at the serial port
of the PICAXE. A logic zero results in

2200 Hz and a logic one in 1200 Hz.
This FSK signal consists of a sine wave
with low distortion and has continuous
phase when transitioning between the
two frequencies. In this way unwant-
ed higher harmonic frequencies axe
avoided an the audio input of the vid-
eo transmitter. These generally have a
bandwidth from 50 Hz to 10 kHz, The
amplitude of the FSK signal can be
adjusted with PI to maximum modu-
lation but without causing distortion
or interference with the video signal.
For the transmitter module we use an
AWM630-TX from Saelig.

The dimensions of the AV-T PCB are
determined by the diameter of the
rocket, together with the dimensions
of the video module, camera and bat-
tery. This results in a reasonably large
PCB of 6 by 13 cm (see Figure 5). As

a result the prototype could be built
with standard components. The PCB
artwork files can be downloaded from
www, e t e k to r-e I e c Iron ics.co.uk
During the launch the circuit board is
subjected to an acceleration of several
g (ly = 9.8 m s 2 ). The leads of some
components could bend as a result, for
example those of an axial Tantalum ca-
pacitor. It is best to fix those compo-
nents that are sensitive to this in place
with silicon adhesive.

Power supply

The MAX? 61 (ICl) step-up switch-
mode power supply delivers a regu-

lated 12 V/150 mA at a minimal in-
put voltage of 5 V, A 9-V PP3 battery
is therefore eminently suitable as the
energy source for the video camera
and the transmitter. After the rocket
has landed, the PICAXE switches off
the camera power supply (via T1 and
T2), but leaves the transmitter mod-
ule powered up. The racket can then
be easily found by tracking die trans-
mitted signal, The battery is therefore
loaded with the maximum load for only
a few minutes.

The I.IAX761 uses a switching frequen-
cy of 300 kHz. In this way the efficien-
cy remains reasonably high. A disad-
vantage is that at this frequency ex-
tra attention has to be paid to the PCB
layout and the choice of components.
LI. in addition to having a ferrite core,

needs to have a saturation current of
more than 1 A and a DC resist f ze of
less than 0.1 Q. To limit radiah i ener-
gy, toroidal cores, pot cores or shielded
inductors have to be used Diode D2
needs to be a high-speed 1 A Schottky

diode. The crime consideration for the
.

output capacitors C2, C4 and C5 is a
low series resistance (low ESR). That
is because ESR is the main cause of
ripple in the output voltage.

In addition to the AV-T circuitry, the
MAX883 (IC2), a low-diop, 5-V regula-
tor IC also provides the power for the
sensors that are connected to the rib-
bon cable. Depending on the battery

2/2007 -

27

TECHNOLOGY

ROCKETRY

DESIGN CONTEST:

Sky-rocket your own design!

the Nettie Hands — Ihe exact location is not known yei. Scandinavia
or Poland are under canstde raiion, A comp Jets ground station will
be built on location, complete with tents, generators and assembly
facilities*

Designs need to be submitted io Elektor Electronics before \ July
i 2007 send to Elektor Electronics, Regus Brentford, 1000 Great
West Road, Brentford TW8 9HH, England,
mentioning 'Racket Contest

Efefrfor Electronics and NERO (Dutch federation
for Rocket Research) together have organised c
design contest for an interesting payload that ,
based on apparent suitability, will /// on the
rocket that will attempt io break the Euro-
pean altitude record in 2008 > In this
attempt it is the intention to
reach an altitude of no less
than 40 km . jmSK ( ) 1

NERO has occupied ilsdf sines
1959 wjth ihe design, con-

■o-jnening cf A

ometcur rockets, fr. the Al

NERO ha* oaggEd /A|

a u •" ” L - ‘ or rc-co-oi the f f __

■ ft 1 -b !

r. ' .1 ■; . -he t'-v Eo

flight with c hybrid mo

i }

to- a-:d the -'re? Durch

■ wO‘S rage • ic«;e: r'o-v. II

Kockei amateurs 'rorr M

NERO a -j busy 1 r r a «
project ro Dr^G-: the Eu- W

• c p = a n a i t i • u d e - e c c ■ to - n|
amateur rockets, A project 'll
team of 1 4 people is busy '

with the design and construe- V-^rhh^EJ?^

tion of a two-stage rocket that nA 1

wi || have to ru rn Ihr s i nto rea I ity m

rude record, that stands at over ten kilo-
metres, to the Netherlands and improve it by
about thirty kilometres,

\ — tL A >

The submitted design needs to contain ah interest-
ing experiment (for example measuring the Earth's mag-
netic field with sensors or measure rotation based on Ihe
sun's position). The mechanical and electronic requirements
that the design has !o comply with can be downloaded from
the Elektor Electronics website [3],

The submission must comprise an electronic as well as a
mechanical design. In addition Ihe design needs to pay at-
tention to:

*> the method of testing, qualifying
and calibrating on the ground;

& the method of activation in the rocket;

o the method of protection against vacuum and condensation;

ft the relevance of altitude for the experiment;

c the method of storage and retrieval of the measure menl data.

A winner will be chosen on the basis of ihe submitted designs. The
winner may let the design fly or a qualification flight in the Nether-
lands, If Ihe design is deemed suitable for launching with the altitude
record rocket (safe enough, light enough and reliable enough} then
launching with the altitude record rcckel becomes on option. Due
ro air traffic regulations the altitude record will take place outside

strongest signal from the three antennas is selected and split across
three computer monitors. The first screen will show the red-time video
signal from the rocket, the second screen a map of the surroundings
wilh ihe position of the rocket superimposed and on the third screen
vital Information regarding the functioning of ihe board systems of ihe
H10 and ihe actual altitude cf course!

28

Eiefcmr&lndronk* - 2/1007

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that is used, the MAX883 can deliver
more that 100 mA, Output LBO goes
low when the input voltage drops be-
low 6 V. The PIC AXE checks the output
from the MAX883 and can generate a
warning when the battery voltage is
too low. The transmitter module has its
own regulator (104).

Ground station

At the receiving side there are no lim-
itations with regards to the antenna
used. So we can use a Yagi direction-

al antenna with high gain. The range
through the air (in a straight line with-
out any obstacles) can then amount
to several kilometres. The greater the
number of elements on the Yagi, the
larger the range and directional sensi-
tivity, But since the antenna has to be
pointed manually towards the rocket,
high directional sensitivity and large
size are not convenient.

There are plenty of choices for cheap
ISM video/audio receivers and most
of them can be easily attached to the

base of the antenna to limit the cable
losses at 2.4 GHz.

The circuit that is mounted on the an-
tenna (Figure 4} p uses a small Airwave
AWM634-RX module that is powered
from a battery and a 5-V low-drop volt-
age regulator (IC1J. Jumpers K5, K6 and
K8 are used to select one of the four
standard frequency bands. K10 allows
an external audio signal to be con-
nected. K7 allows the choice whether
the direct signal or the external signal
is connected to the FSK- demodulator.
The received video signal is available

r -----

| Firmware !

J Our telemetry system has no firmware — the idea being that you 1

[ write it yourself to match the sensors you wish to use. This is unlikely (

to cause problems as the programming language used on the PICAXE I
micros is really simple.

I The programming language also contains sufficient resources and I

I support for signal measurement and the use of the I2C bus, making
I application software writing a breeze, really. |

To simplify copying your own software into the PICAXE, the transmitter 1
I circuit is equipped with a programming interface. The circuit is |

connected to a PC via an RS232 cable, whereupon the software can be *
I transferred in a simple manner.

2/2007 - flAlor ebdrafiks

29

TECHNOLOGY

ROCKETRY

figure 5. Component mounted on two of our prototype boards.
Aboie: tionrmitler; below: r«eJveo

on the outside on K2.

The demodulator circuit for
the data is based on the same
chip as that used on the AV-T
board, the FX614. In this cir-
cuit however, pins MO and Ml
are set so that only reception
is enabled. The demodulator
has an input amplifier and a
band- pass filter. If the signal
drops below a certain refer-
ence level the DET-output
prevents erroneous data from
being sent to the serial port
of the PC.

To record the data it is best
to use a camcorder with an
S -video input. The video sig-
nal can be played back on a
TV and the demodulated au-
dio signal can be connected
to the serial port. In this way
synchronised video and data
can be examined.

Seim aWare Solution's Stamp-
Plot Pro software generates
nice charts from data received
via the serial port. This Win-
dows application accepts
data as a string or as binary
values with up to ten chan-
nels. The program has many
powerful options that can
store raw or processed ana-
logue and digital data, arrach
a rime stamp and display it on
a chart, A free evaluation ver-
sion can be downloaded from
the SelmaWare website J2j.
You can also find a number of
example applications on this
website, including an applica-
tion that overlays a recording
from a PC -video capture card
with a StampPlot Pro screen.
Although the system de-
scribed in this article has been
developed for rocket appli-
cations, it is also suitable for
other video/telemetry systems
such as remote controlled air-
craft including helicopters,
cars, boats or other interest-
ing development projects.

■■ : -

Web links

[ 1 1 vavw. p i cc .CO . u •:

[2J WiVW.se! maware.com
[ 3 ] v/vAv.e lekto r- e !e d ro rt i cs . ca . uk

COMPONENTS LIST ]

{transmitter) I

Resistors |

R1,R2.R3,R6,R1 1 t Rl 2,R1 3.R1 6 r R17 =

10kQ

R4,R5,R8 = 3kQ3
R9 = 2kQ2
RAR10 - 12kO
R14 = 1 k£2 preset

R15 = 22QH 1

Capacitors |

Cl,C2,C5,C13 r Cl8 = 22uF 1 6V radial |
C3,C4,C6,C7~C]2,C16,CI7,C19 =

1 QQnF

Cl 4, Cl 5 = 18pF -

Semiconductors

D1..D2 = I1DQ03

1C1 = MAX7$ *

1C2,IC4 = MAX883 1

JC3 = PICAXE-I8X I

IC5 = FX614 1

T1 = SC557

12 J3 - BC547 |

Miscellaneous

K1,K2 = 2-woy PC6 terminal black ]e,g.

Phoenix Contact # 1 725656 '

K3 = 1 4-way boxheader
K4 — RCA connector I

K5 = SMA connector I

K6 = 9-way sub-D connector, female, I
PCB mount |

LT = 22 /jH

*. \ O D 1 — AV/M630-TX Low Power Radio
Solutions)

XI = 3,579MHi 1 3. 5 8 MHz) quartz crystal
PCS, ret 050238-1

I (receiver)

| Resistors

R1,R2,R5 = 10kP
R3.R4 = lOOkO

Capacitors

Cl = 22uF 16V radial
C2,C3,C6,C7,C8,C1 1-C14.C1 6 =

■ lOOnF

I C4,C5 H C9 f Cl 5 = 10/iF 16V radial
| CIO = 470 ^jF I6V radial

I Semico nd actors

D1 - 1IDQ03
D2,D3 = 1N414S
(Cl = MAX883
IC2 = MAX232 DIP co^

1 IC3 - FX614

I Miscellaneous

I K1 — 2-way PCB terminal block (e.g.

| Phoenix Contact 1725656]

| K2,K9,K1 0 — RCA jack, PCB mount
( K3 = SMA connector

K4 = 9 -way $ub-D connector, female.

PCB mount

K5,K6 r K8 = 2 -way pinheader
K7 = 3-vvay pinheader
MODI - AWM634-RX (Low Power Radio
I Solutions)

1 XI = 3.57 9M Hz (3. 58MHz) quartz crystal
| PCB, ref. 050238-2

L _ _ _ — _ _ — — — — — *

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2 ; 2007 -elfktGf tlstfronics

31

HANDS-ON

PIC24F DESIGN SERIES

PI

Jan Suiting & Luc Lemmens, in cooperation with Microchip Technology & Labcenter Electronics

Assuming the free Explorer- 16 CD-ROM you got with last month's issue was not mislaid, Ebayed off or
frisbeed out of the window we can continue with a look at the hardware to go with this article series
brought to you exclusively by Microchip, Labcenter and Elektor. Software is covered, too, by a Proteus
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Reset button

development

Connector for optional I
graphics LCD

Analogue input
adjustment

H

2 line by 1 6-character t

™ \

Prototyping area

c* » • ■

< 1 o f ■

ICD connector (in-
circuit debugger)

. J ',- t tll< It 'Ml i 1

PIC/PIM selector

m

USB connector

A PIC1SF USB device! \

RS232 serial port

Power indicalor LED

Power input (accepts
9-1 5V DC)

MlCflOvHIF

t 5V / GND / -f 3.3V
probe hookup eyes

indicator LEDs {port
configurable)

PlCtail Plus expansion
bus connedor

JTAG conned or

Pusbuffons on user-
defined inputs

Figure ). The Eipbrer-16 board plrtmcd ham nbove- Her?, the PIC2-IFJ is shown inserted.

32

elector eletlronkf - 2/2007

Part 2: Explorer-16 Value Pack and

audio signal processing

i — i — — -

The free Explorer-16 and PIC24F downloads tell more
than can be printed in this entire magazine

PIC24FJ1 28 iGG-pm
piug-m module (PI M)

J

PlCtail Plus expansion
bus PCB edge
connedor

PiCkii 2 Programmer
connector

*“^^^eMonEEPROM^^|

PlCtail Plus expansion
bus connector
(optional)

Good response was received to our ini-
tiative to supply a free CD-ROM with
the complete European print run of Els-
kior Electronics January 2007, Feedback
ranged from 'nice to be able to run such
a simulation of a complete microcontiol-
ler board, all free of charge' and “ho-ho
a free C compiler for high-end PICs 11 to
"can't wait to buy the Explorer- 16 hard-
ware”, Before we start with a look at
the Explorer- 1 6 Value Pack, there are
some additions and extras to mention
that come in the wake of publishing the
January 2007 instalment.

Will not fit on a page or two

An immense amount of free documen-
tation. including an introduction to
PIC24F programming, tutorials, da-
tasheets, application notes, Power-
Point presentations and a lot more has
been compiled and gathered for you
on the Explorer- 16 page of our web-
site. You'll find it at www.elekt or- elec-
tronics. co.uk /explorer- 16 Tills page is
only accessible to registered users — a
login screen will be shown.

At the time of writing, some ten down-
loads are available that tell more
about Explorer- 16 and the PIC24F de-
vice than can be printed in this entire
magazine. The video presentation by
Don Schneider is highly recommended.
The presentation comes as a Windows
Media File (wmf) with a size of about
40 MB. A ‘stilT version in the form of a
pdf is also available and takes much
less space.

Besides this Aladdin's Cave of free
software and documentation for PIC
enthusiasts (in particular the 24F de-
vices) we are running a dedicated Ex-
plorer-16 topic on our online Forum,
v Questions the authors are unable to
answer (but give us a try) will be for-

warded to f or dealt with directly, by ex-
perts at Microchip and Labcenter

Explorer-16 Value Pack

Before moving on ra the hardware we
have on offer we should reiterate here
that the Explorer- 16 CD-ROM you got
for free with last month's issue can be
used on its own for as much Proteus
VSM simulation, C language practising
and PIC programming as you wish —
all without the need to buy hardware.
In response to feedback to January’s
free CD-ROM we should stress that the
Proteus simulation tools in particular
do require a relatively fast PC so it's
unwise to try running these on a 486
machine or under Windows 96 — you
will only frustrate yourself.

There is a vast amount of permanently
useful information behind the seem-
ingly simple opening menu on the CD
— the information that's free from Mi-
crochip and Labcenter websites would
take you a long time to locate and col-
lect even on a broadband internet con-
nection. The special release of Proteus
VSM with the PIC24F simulation mod-
ule cannot be found anywhere in this
form as it was specially made by Lab-
center Electronics for Elektor readers.
The Explorer- 16 value Pack, then, rep-
resents gieat value for money as you
can check for yourself using the two
insets. It is only available from Ele-
ctor Electronics at a special discount-
ed price. Ordering details for the pack
may be found on the SHOP pages of
our website. So, what's in the pack?

Explorer-16 Demo Board

This is the main component of the Ex-
plorer- 16 Value Pack. An attempt at
"functional dissection by component'

2/2007 - ddtfor dalnsua

33

JJjJJJJjJJJ PIC24F DESIGN SERIES

nector at ihe underside made from four
5IL receptacles arranged in a square.
Details on bow 10 use the Explorer- 16
board ‘out of the box’ may be found in
the Development Board User s Guide
that's available on the CD-ROM sup-
plied with this beautiful kit. Besides
acting as a development platform, the
demo board may be used straight away
for real-life applications of PIC24F and
dsPIC33 micros.

In good Microchip tradition, tutorial
programs are available to get you go-
ing in no time. What's more, these pro-
grams are pre loaded on the two PIMs.
The Explorer- 16 board is powered
from a mains adapter with a capacity
of about 250 mA at 9-15 volts DC. User
programs are stored in non-volatile
memory. If desired, they are automati-
cally executed at power-on so you can
transfer the software you’ve developed
on Explorer- 16 to the application circuit
simply by relocating the FIM. Your ap-
plication circuit needs to have four 25-
pln 0.05 inch pinheader receptacles
just as on the demo board. To avoid
costly mishaps, always observe the
bevelled edge indicator on the PIM.

PiCkit 2 Starter Kit

The second main item in the Value
pack is the PICkit 2 which may be fa-
miliar from its hugely popular pred-
ecessor the PiCkit 1 . PiCkit 2 comes
with the Low Pin Count Demo Board 1
which supports 8-, 14-, and 20-pin PIC-
MCUs. We probably don't have to spell
out that this makes a useful tool even if
you do not regularly use the hefty Ex-
plorer- 16 board, but there you are —
it’s printed.

The PiCkit 2 communication module
is plugged onto the 6 -way pinheader
on t he Explorer- 16 board and hey pres-
to you can do vour programming and
debugging. PiCkit 2 comes with its
own documentation, user guide and
software, all on yet another CD-ROM.
PiCkit 2 is pictured in Figure 2.

Audio PICtaii Plus

The Audio PICtaii Plus Daughter Board
included in the Value Pack and pic-
tured in Figure 3 can be plugged into
the Explorer- 16 development board. It
is used to create analogue waveforms
from a PWM signal. To do this it uses a
low-pass Liter (LPF) which is preceded
by a potentiometer that can be used to
change the volume. The output of the
LPF is then fed ro a speaker amplifier.
This amplifier allows either the onboard

Figure l. FiCkil 7 is a kil-m-a-kitwilh gresl potential for oil Pit users as it confabs a debugger and a progmmnwr.

is shown in Figure 1. The demo board
has an overall size of 140 x 115 mm and
comes with two MPU modules; one
PIC24FJ and one dsPIC33F. Microchip
calls these *PIMs' (one m' there...), for
plug-in module . Both are 100-pin plug-
on modules with a square footprint. Al-
though we’re using the PIC24FJ PIM
for this project, the dsPIC33F PIM is
a good catch for those of you wishing
to delve into digital signal process-
ing Lots of information is available on

the dsPIC series from the Microchip
website.

Both the PIC24FJ and dsFIC33F PIMs
can be obtained as one- off s from Mi-
crochip-Direct (or national distribu-
tors) for the purpose of building stand-
alone application circuits developed
using the Explorer- 16 motherboard and
PiCkit 2. The modules are not too ex-
pensive considering that the PICmicro
ICs come ready fitted on a 40x40 mm
size carrier board with a 100-pin eon-

Figurs 3. The Audio PICtaii Pius Loaid taalained in Ihe Explorer- 1 6 Va I us Pack.

34

etektoretetfraniG - 2-20Q7

speaker to operate, or the external
speaker connected to the jack. You can
connect a cable from this jack to ampli-
fied speakers to boost the sound level
i or large rooms. The amplifier automati-
cally detects ii something, is connected
to the jack and will turn on the onboard
speaker. The design also includes a
serial EEPRGM which can be used to
store compressed speech files.

A few pins of the angled pinheader on
the board will need to be isolated as
they are dangerously close to the pins
of the JTAG connector on the Explorer-
16 board.

More hands-on simulation:

Audio PICtoil Plus in VSM

This month we do our second simula-
tion using Proteus VSM supplied on
the free Explorer-16 CD-ROM (January
2007).

Download the file Demo2.zip from the
Explorer- 16 page at www.elektor-elec-
tronics.co.uk.. explorer- 16. Save the un-
zipped Demo2 folder the directory: c:\
program file s\ micro chip \mplab c30\ex-
ampies. Buckle up.

The audio PIC tail virtual demo board
for VSM is a cut down version of a full
hardware variant in that some of the
Explorer- 16 demo board and some
components on the Audio PlCtail have
been removed for clarity and also to aid
Simulation time. The demonstration
board, though virtual, will not fail to
show the capabilities of Proteus VSM
and the PIC24E

To keep the download size reduced, the
Audio Analysis Graph will contain no
data, therefore a simulation will need
to be performed in order to listen to the
sound output on the PC,

The Ant o PlCt ail demo con ,-ists of two
sheets, le one shown in F*. ire 4 con-
tain? Hi _aidio elements of the PlCtail
and the interactive elements needed
to run the VSM simulation. The second
sheet contains the PIC24F required to
run the source code. Some elements of
the hardware are removed since this
is a pure simulation we are performing
rather than a simulation as part of com-
plete des^.i with PCS, The demo is
node-locked so no components can be
added or removed. However the demo
will allow you to modify passive com-
ponent values and hence change the
characteristics of die filter. The results
of these changes can then be viewed in
the Frequency Response Window. The
C source code can also be changed, so
you will be able to analyse the speech
output from the source code attached

Fig v re 4. Audio FJOaif Virtual Cterrra Boord with c II esranlid Interactive dements.

to the PIC24E

The ability to run both an Audio Analy-
sis and a Frequency Response on the
same simulation would normally re-
quire a full version of the software to
remove the connection to the MCU
and add a sine wave generator. How-
ever the boffins at Labcenter have de-
vised a new interactive switch (Fig-
ure 5) which will ensure that the two
signal sources can remain mutually
exclusive.

The switch position should be changed
to suit the type of graph analysis you
wish to perform. Just click on it.

© Select RDO to use the audio graph
and replay audio generated by the
P1C24.

© Select REF to use the frequency
graph and display the frequency re-
sponse of the filter.

Figure 5. Interactive virtual switch.

The Audio PlCtail also has interactive
elements for:

• pushbutton to start code in real-time
simulation

© temperature sensor

The pushbutton is required to allow
the source code to perform an ADC
reading, subsequenrly compute the
relevant value, and then output the
speech. Also included in the pushbut-
ton seer ion is a stimulus injection, see
Figure 6. This is required to allow the
Audio Analysis Graph to operate, since
in batch simulation mode the interac-
tive components are disabled. There-

Figure 6.1frferaf1iv£ pu-fh faulloji and bal th m&cte sIEjt- us
Enjsdicru

Figure h Interactive TCI 04 7 temperature sensor ord DYM - oil
virtual I

2:2007 - e lelter dsfranits

35

HANDS-ON

PIC24F DESIGN SERIES

Figure 0. Virtual Gulp jI filler stage using the MCP602Z,

fore without this stimulus the batch
simulation would be unable to run.
The temperature sensor (Figure 7) is
a fully interactive comp onent. This will
allow the designer to modify the tem-
perature using the J and J buttons.

such operations, wich would be rel-
atively difficult with physical hard'
ware. These of course help reduce the
number of code iterations and there-
fore may aid a reduction in debug and
test time. As a additional aid to this

The output filter section {Figure 8) is
the same physical topology and values
as provided on the actual Audio PIC tail
hardware. However the output driver
stage has been removed and modifica-
tions have been made to allow simula-
tion to be performed as outlined above.
The bonus with the simulation is that
it will allow you to quickly and easily
change the passive component values
to change the filter response. This re-
sponse can then be checked by run-
ning a simulation using the Frequency
Response graph. The other benefit af-
forded by simulation is the ability to
analyse and save the speech output
to a .wav file, which will allow filter
modifications and code changes to
have some form of offline quantifiable
analysis performed quickly and eas-
ily. Great stun for microprocessor Ians
keen on using digital audio.

To allow simulation to be performed, a
Voltage Probe is attached to the filter
output. In tliis case it has been labelled
Audio'. This is then used as a reference
for the traces within a graphical analy-
sis window.

The Explorer-16 Value Pack is only available
from Elektor at a special discounted price.

The output of the temp sensor will vary
exactly as per the datasheet specifi-
cations and can then be read by the
PIC24F ADC. Tills capability allows the
designer to perform operations such
as limit checking of code, response to
expected ADC value and many other

process, a virtual voltmeter has been
attached to the output of the temp sen-
sor. This should allow you to determine
if the values being referenced in code
for a given ADC reading are meaning-
ful relative to the set temperature and
expected sensor output value.

Figure 9. AurffoAnalpii vjfndaw mcnimised.

Running the Demo

The code should run out of the box
within ISIS as the PXC24F will be point-
ed at the .cof file in the design direc-
tory. To use the design with MFLAB =
a build operation may be required.
MFLAB will prompt if this is the case.
The Audio Analysis graph will allow
you to record and listen to the output of
the design. The analysis is performed
as a batch process and the Spice calcu-
lations are performed based on a com-
puted output from the PIC24F. This
allows the VSM simulation engine to
perform a mixed-signal analysis and
offer such features as the audio analy-
sis capability.

The operation of the graphical simula-
tion is largely the same regardless of the
design being open within the Proteus
ISIS schematic capture package, or the
Proteus VSM window within MFLAB.
The basic operation is to ensure the
interactive switch is in the correct po-
sition for the signal source required,
move die cursor over the Audio Analy-
sis graph in the schematic and either
press the space bar or right click and
select Simulate Graph. The Simulation
engine should then run. It successful,
the speech output for the set tempera-
ture (in degrees) should be seen as an
audio waveform. To listen to the out-
put again you can press CTRL-space or
right click and select Play Audio*

36

eiehordafTimki - 2/2007

Explorer-16 Value Pace

As of Ihis Article instalment Eiektor sells the Explorer* T 6 Valve
Pack, It consists of four components packaged together in a sin-
gle box:

I. Explorer- 1 6 Demo Board

A modular development system for Microchip's new 1 6-bit mi-
crocontrollers. It supports devices from the. FIC24F, PIC24H, and
dsPIC33 families- It Is capable of interfacing with 5V peripher-
als and also provides basic generic functionality with the added
ability to expand to vertical markets via modular expansion. The
board comes with one dsPSC33F256GP71 0 plug-in module, one
FIC24FJ 1 28GAGT 0 module, an R3232 data cable and c CD-ROM,

2* PIC Kit 2 Starter Kit

A PIC -hi 2 Microcontroller Programmer and a PICkit 2 Low Pin
Count Demo 3cc-rd containing c PICl 6F690 PDIP for getting started
with programming baseline and midrange flash microcontrollers.
PICkit 2 takes advantage of Microchip's Pul l- Speed USB device- The
Lo w Pin Count Demo Board supports 8-, 14-, and 20-pin PICrrric-
ros. In addition to the PICl 6F690, the board comes with 4 LEDs, a
pushbutton, and a potentiometer. Also included are 12 lessons to
help get developers up to speed quickly on programming PIC micro
MCUs.

3. Audio PlCtail Plus daughterboard

This plug-in board for the PlCtail bus on the Explorer- 16 Demo
Beard effectively turns digitized audio inro an audible signal that can
be heard through the on-board mini speaker or through a set of
amplified speakers.

4* MPLAB C30 Discount Voucher

By completing this voucher and returning it to Microchip, you change
your student version of C30 Into a full version for £94. » 2 less then
the list price of the full package.

The graph can also be expanded to
perform additional operations — this
is achieved by clicking in the title bar
of the audio analysis graph which is
embedded within the schematic. Tills
should then provide a maximised win-
dow as shown in Figure 9.

The mechanism for the Frequency Re-
sponse graph is the same as for the
audio analysis, however the interactive
switch will need to be set to Link the
sinewave generator into circuit.

Using MPUB and
Proteus VSM to Debug

The real capability to perform a sys-
tem level debug operation is achieved
when MPLAH and the Proteus VSM
plug-in are married together. This
combination allows VSM to become
the development tool within MFLAE
and operate in a similar manner to
using MPLAE-SIM or MPLAB ICD2.
The big difference, however, reads:
'no hardivare required' and the ca-
pabilities of VSM allow a much more
interactive code simulation to be per-
formed. Tins allows serial ports, A/D
converters and other asynchronous
operations, which are generally diffi-
cult operations in a code simulator, to
be performed with uncommon ease.
The benefits or mixed -mode simula-
tion are very much apparent when a
debug operation is performed.

Your savings

Thanks to on exclusive and one-off
arrangement with Microchip UK. the
Explorer- 1 6 Value Pock is both unique

(you won't find it anywhere else in this configuration) os well os much cheaper thon (he in-
dividual! components.

Ifem

Explorer- 16 Demo Board DM240001
PICkit 2 Starter Kit (DV1 64120)

Audio PlCTail Plus (AC 164 125)

Subtotal

VAT

Total

F&P

Item

Explorer- T 6 Value Pack, indudes
DM240001 , DV] 64 1 20, AC 164 1 25,

C3G discount voucher
VAT

Total

P&P

Micro rh/p-D/recf price (E)

£69.45

£26.71

£33.00 (tentative)

£134.16

£23.43

£15764

depends an destination!

Eiektor SHOP price

£122.90 (€ 179.00 / U55 232.50)
included

£122,90 (€ 179.00 / USS 232.50)

(depends on destination,

Assuming you complete and return the C30 discount voucher (20% off the list price of
£4 70.61 } 4 the total saving you get through ordering an Explorer- 1 6 Value Pack may
amount to £1 29 TS7J.

iabcenter VSM plug-in modules

fnese cj.s ; -a,e z 5_ze" ’c : : -czze r s a-, arable -i

ww\v. labcenier co.uk/producte/ e/e ktaraffer.hlm. Simulation of micrccant refers. in re a Mite
circuits is the way forward and Proteus VSM c market leader in this area.

5/2007 - dektir dstinsiiQ

37

1ANDS-GN

PIC24F DESIGN SERIES

Figure 1 1. Selecting PnoHeiis VSM as debugging led.

Figure 10. MPIAB and the Frafsus VSM viewer window.

figure 12. Cofrelalion betoken a Seed ADC breakpoint, Scf
Tamperalure, Sensor Output Voltage and resollanl ADC reeding.

However, keep in mind their Proteus is
a view window within MPLAB — see
Figure 10. Whilst the functionality is
similar to that of the actual schemat-
ic environment, some operations, such
as placing components, cannot be per-
formed since these are better suited to
the schematic capture package. How-
ever, it is still possible to modify com-
ponent properties and add items such
as virtual instruments and hook these
up whilst in the viewer. Batch simula-
tion operations can also be performed,
so it’s easy to make
a code modification,
build the source code
tree and then move
to the viewer and run
an audio analysis us-
ing the same actions
as would be used in
i he schematic capture tool.

The viewer can operate in effective-
ly two modes. To run a batch opera-
tion, the viewer needs to be opened.
Do this: Debugger — * Select Tools — »
Proteus VSM.

As shown In Figure 11. this will open
the viewer window and will show the
sratus of the connection to the VSM
Simulation engine in the toolbar. In this
case the green button indicates that
the connection is yet to be made. How-
ever it is in this mode that the batch
simulations for Audio Analysis and fre-

quency Response can be performed. If
the green button is pressed, a link to
VSM is formed to allow the real time
simulation of code and system to be
performed. This will then make the
standard simulation buttons in MPLAB
active, keeping the process of simula-
tion and debug seamless across all of
the debug tools, both hardware and
software.

You can now:

O add a breakpoint on an ADC event;

ue held in tire ADC result register;

• view the set temperature on the
temp sensor;

• view rhe output voltage of the temp
sensor.

In other words, correlate all the ele-
ments and functions as illustrated in
Figure 12. How does this speed up
things? Well, as can be seen we can
now very quickly determine that 20
degrees C is an output voltage of 0.7 V
which results in a ADC reading of
0x0 0D 9. We can also quickly determine

if the values for the sensor and ADC
are correct and take the necessary
action. Tills operation is significantly
simpler than trying to accurately time
external instruments with debug tools
to achieve the same net result.

Conclusion, outlook

The above descriptions are aimed
at providing an insight into the Au-
dio PICrail and the MPLAB and VSM
Viewer tools. Whilst being relative-
ly brief and covering
a lot of ground they
should serve to Intro-
duce a few basic con-
cepts and operations
prior to simply trying
things out.

In Part 3 of the series
we'll look at interfacing mass storage
cards and revert to our speaking ther-
mometer. this time in hardware.

Join our online Forum topic on the Ex-
plorer-16 series and tell us how you get
along.

■ -■ ,—ili

Update, emersions and download* tar J lib article jerks are
poit td a I w w el ekt « - e ! ad ran its. to. u k ei p tar ec ■ 1 6

Tu I All trademarks and copyrights a I filicrchdiip and
la tauter Electronics acknowledged

® add a Watch window to view the val-

The video presentation by
Don Schneider is highly recommended.

36

Efeldor slearciua - 2/2007

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Stn3EA4

Postage.
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£4. 99- £12. 99
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P&P Cost
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2/2 007 - els Lor detfronki

39

Stereo mic op one

Marcel Cremmel

There are still a lot of hobbyists who enjoy
making high-quality live audio recordings of
concerts, interviews, radio broadcasts, natural
sounds, and so on. Professional equipment such
as Nagra and the like is simply too expensive.
We can thus be thankful that many
MP3 players are equipped with
an analogue input and a high-
performance MP3 or WMA encoder.

You need portable equipment if you
want to make recordings in the field.
Professional equipment for this pur-
pose is very expensive, and many af-
fordable alternatives (such as MP3
players) cannot handle microphone
signals. Microphones require some sort
of assistance to supply the high signal
levels that must be pro tided on the line
inputs. Although some players have
built-in microphones, the quality is of-
ten barely adequate for use as a dictat-
ing machine. This means you need a
microphone preamplifier to adapt the
microphone output to the line input.

The characteristics listed in the *MP3
preamplifier features* inset can be ob-
tained without using any special com-
ponents. Transistors and opamps that
you have rucked away in a drawer
somewhere should tio just fine. Aside
from the potentiometers and con-
nectors , all the components are SMD
types. But there's no need to be afraid
- even beginners can assemble the cir-
cuit board if they are blessed with a

grain of patience, an ounce o! dexterity
and a pinch of precision.

Microphones

Even the best preamplifier won't per-
form well with a mediocre microphone
or a poor cable. A wide variety of sys-
tems are available, with prices ranging
from a few euros to several hundred.
The preamplifier described here is op-
timised for dynamic microphones. The
characteristics of the microphone (see
the Principal characteristics of a mi-
crophone' inset) are a major factor in
selecting a microphone.

The Sennheiser MD21 is a genuine re-
porter's microphone that has been on
tire market for several decades already.
It has a sensitivity of 1.8 mV/ Pa and
generates an output signal of 0.36 uV
in a quiet room, or 3.6 mV if you aim it
toward a pneumatic hammer.

It has a very large dynamic range:
3.6 mV ^ 0.36 uV is a healthy 30 dB.
Based on this information, we can

specify the following properties of an
ideal preamplifier:

® An input noise level that is signifi-
cantly less than 0.36 uV. in order to ob-
tain a satisfactory signal-to noise-ratio
{SNR),

• No overdrive or signal distortion at
3.6 mV

A good SNR can be achieved by using
a well-considered design and choice of
components for the preamplifier The sec-
ond property requires using a potentiom-
eter so the output level can bs adjusted to
suit the maximum acoustic pressure.

The distance between the microphone
and the preamplifier is often mors than
10 metres. The cable used for this link
is thus exposed to interference from
magnetic fields, in panicular AC mains
fields at a frequency of 50 Hz. The sig-
nal carried by the cable has a low am-
plitude and must be protect a d against
this interference, since othenvise the
interference will be audible as the well-
known "mains hum . This protection is

40

either elcTlninis - 2/7007

provided by the screen of a screened
cable. For proper operation, the screen
must be connected to ground, and it
cannot be used to carry the signal.
Despite this protection, some inter fen
ence signals still manage to reach the
active conductors. If these conductors
have the same impedance relative to
ground, the induced signals will also
be the same. Their effect can then be
neutralized by the differential input
stage of the preamplifier. In addition,
the low impedance of a dynamic mi-
crophone reduces the effect of external
interference.

In short, use a screened cable with
two conductors and solder the cable
together as shown in Figure 1 ,

Features

• Si£T“0

• Compatible with dynamic and eiecifEt microphone?

• Maximum input* sensitivity: 50 , 60 or 70 dB. selectable

• Level control using two potentiometers

• Bandwidth: 50 Hz to 50 kHz at maximum gain 70 dB

• Distortion: 0,04% at —1 0 d8V |3 1 6 mVy

0,1 2 % at 0 dBV (1 \y

• Input noise: —1 24 dBV [0.63 pV^J

• Power source: 9-V battery

• Current ca resumption: 3 mA per charnel

• Designed to fit in a commercially available enclosure with □ bolter/ comaorimEnl.

Schematic diagram

The schematic diagram consist of two
identical amplifier channels. Here we
describe one of the two channels.

The circuit is powered by a 9-V battery.
An LED wired in series indicates that
preamplifier is switched on. The volt-

age drop of the LED (1.6 V to 2 V for a
red LED) does not affect the perform-
ance of the preamp. Toe supply voltage
is switched via the contacts of the au-
dio socket. In the quiescent state, two
contacts prevent T9 and TIG from con-
ducting, The TMOS transistor is thus

cut off* so no voltage is applied to the
other components. When a microphone
cable is plugged in, the contact in the
socket is opened, Tire supply voltage
is now applied to the gate of T9 or T1Q
via R3 or R33, The TMOS transistor is
thus switched on and provides power

2 2007 - e-dr&r deftionlcs

41

AUDIO

fie jfc 1 Cortflrurtion oi ihe screened cable fink between IfiE
Enfcraphone and the preamplifier

to the amplifier channel. The high re-
sistance of R3 and R33 limits the cur-
rent consumption to 1 .6 uA per chan-
nel in the on state

Amplifier design

Why is it necessary to amplify the sig-
nal? The line input of an MP3 player
requires a peak signal level of approxi-
mately 1 V, which means 2 V peak -to-
peak. This range is converted to 16-bit
digital values in the device, which thus
provides a resolution of 30 nV Howev-
er, the signal produced by the MD21
at a normal conversation level is only
3,6 uV r which is much to low for the
analogue-to-digital converter (ADC) of
the MP3 player. If you connect the mi-
crophone directly to the player, you wall
make a recording without any sound.
For a satisfactory SNE, the level of the

signal applied to the input of the play-
er must be at least 100 times as large
as the value of the least significant bit.
which means at least 3 mV. The signal
from the microphone must be amplified
by a factor of 833 to achieve this level
Tills is the job of the preamp liner.

The preamplifier described here pro-
vides a choice of three gains: 315
(50 dB), 1000 (60 dB) ( or 3150 (70 dB).
Such high gains cannot be obrained in
a single stage in combination with an
acceptable bandwidth, so this task is
split over two si ages. The first stage is
built using discrete transistors, while
me second stage is implemented using
an operational amplifier.

In the first stage (shaded grey in Fig-
ure 2), you can see the classic struc-
ture of a differential transistor amplifier
(T1 and T2). The microphone signals
arrive via EN 1 and IN2, with the capaci-

fb’T? i, Fulljchenotk diagram d Ihemkrophcrte preamplifier Ini MP3 pliers.

42

Elehor^etfroniu - 77G07

tors providing DC blocking to avoid up-
setting the DC bias setting. The out-
put of the first stage is taken across
the collectors of T! and T2,

The gain is determined by the equiv-
alent resistance between the two
emitters:

- 2.2 kQ: 13, 6x (23 dB)

- 2,2 kQ I j 470 Q: 43x (33 dB)

- 2.2 kQ 1 1 33 Q: 135x (43 dB)
Transistors T3 and T4 stabilise the op-
erating point of the stage, which makes
it unnecessary to use a matched pair
for T1 and T2,

Why use transistors?

Could be hist stage be built using an
op amp and a few passive components
instead of transistors? The answer is yes
with regard to the gain : but no with re-
gard to noise. This can be shown using
a simple comparison. We compared the
behaviour of two amplifier designs with
the same input sensitivity: rhe transis-
tor stage described above (with SI set to
R12 for a gain of 33 dB) and an amplifier
built using a TL07T which is known for
its low noise level. The frequency char-
acteristics are shown in Figure 3. Both
circuits meet the requirements, but the
transistor stage does it better.

We can use a PS PICE simulation to de-
termine the effective input noise volt-
age. This calculation takes ail noise
sources into account. It yields the fol-
lowing results:

- Design using a TL071: noise level
500 x 1Q~ 1S V-' Hz over the frequen-
cy range of 100 Hz to 20 kHz (white
noise). This yields

V sff = V[(50D X 10- JB | X (20,000)] =

3.2 u V

*

- Design ising transistors . jise level
ll.E ^ 1 10 V 2 /Hz over the frequency

range of 100 Hz to 20 kHz. This yields

V„ E = \ 1(11.5 X 10- ia ) X (20,000)1 =
0.48 uV.

ft

The noise level is thus a factor of 6.6
lower, so the transistor stage wins
hands do r _ This noise level is or the
same order as the signal produced by
the microphone in a quiet room. This
means you can hear a fly buzzing
around in the room.

Strictly speaking, you also have to take
into account the thermal noise gener-
ated by the internal resistance of me
microphone. The MD21 has an internal
resistance of 200 Q. which yields an ef-
fective noise voltage of 8.6 x 1Q _S x \ R

Examples of acoustic

pressures

Condition

P (Pa)

P [dGSPL]

Auditory th res ha id

20 /*

0

Quiet room

200 u

P

20

Conversation

2 m

40

Lively conversation

20 m

60

Busy street

0.2

SO

Pneumatic hammer

2

100

Pain threshold

20

120

-0.12 uV (of 25 "C and a bandwidth
of 20 kHz),

Due to the gain of the first stage, an
opamp can be used for the second
stage with satisfactory results. A
TLG81 can also be used in place of the
TL071 without any appreciable degra-
dation of performance.

The differential structure is maintained
to avoid losing 6 dB in input senslrivity.
Tne gain is fixed at 22 (27 dB ) as derer-
mined by resistors HI 4. R20, R21 and

R22 for the one channel or R42, R43*
R36 and R44 for the other channel.
Potentiometers PI and P2 can be used
to independently adjust the output lev-
els as desired. Capacitors C6 and C15
block the DC component to prevent
crackling from the potentiometers.

Construction

All components except rhe battery are
fitted to a primed circuit board. This

10.00 100.0 1.000k 10,00 k 100.0k T.000M

fc* f [Hz]

Figuie 3. SandwJdlh of !he firs! stags. Bluet liansisbf version. Red: TL071 version*

Principal characteristics
©f a microphone

• Sensitivity rn mV/ Pa
° Output impedance
° Bandwidth

• Directionol sensitivity

• Maximum acoustic pressure

An electronics specialist Is Interested In the first three chard eterislics, white a
recording specialist is interested In the last three*

The signal voltage provided by a microphone is proportional to the acoustic
pressure and the sensitivity of the microphone:

• W — S x P

• S: sensitivity in V/Pa

** P: acoustic pressure deviation fn Pa

2/2007 - eltklor a'Kfrojiia

43

HANDS-ON

AUDIO

Figure 4. Loyouf of Ihe daub he* sided FCB designed for {his proyscf.

is a double- sided, through-hole plated
PCB. If you make the board yourself,
you will have to make the through -
hole connections by hand. The shape
of the board is specifically designed to
fit an enclosure distributed by Fame!!
with a compartment for a 9-V battery.
We selected PCS -mount chassis con-

nectors for the audio sockets to ensure
optimum contact. Note; these axe not
standard versions.

We advise using a soldering iron with
a very fine tip. Start by soldering the
SMD parts, since they will difficult to
reach later on due to the other compo-

nents. Pay good attention to the polar-
ity of the electrolytic capacitors, which
are present in generous numbers on
the bottom of the board.

The SMDs are distributed over both
sides. Handle the MQS transistors caie-
fully to avoid exposing them to electro-
static charges. Be careful when solder-

I COMPONENTS
j LIST

Resistors

R1,R12,R23,R34 = 470 Q
R2,R24 = 100C
1 R3,R33 = 4M£i7

R4,R5,R25,R26 = 3kQ3
I R6,R1 i ,R27,R32 = 6kQ8
I R7, R ] 0, R28, R 3 1 , R4 5, R4 6 = 47kQ
• R8,R9 R29.R30 = 2kn
i R13,R35 = 33Q
i R14,R22,R36,R44 = 220kQ
I R15,R37 = 2RQ2
i R1 6-Ri 9.R38-R41 = 220

R20,R21,R42,R43 = 10k£2
PI ,P2 = potentiometer 1 OkQ, B, Alps type
RK09K1 1 31 0KB -Farnell # 119-1725;

Capacitors

(oil SMD)

Cl ,04,06,07,08,00,01 3,015,06,0 7
r Cl 9-C22 = 1 OpF 16 V tantalum, Vishay
Spraaue 595D1 06X90 T6B2T (Parnell #
392-8895)

02,03,05,09,0 1,02, Cl 4, Cl 8 =

470nF/25 V tantalum, ''/is hoy Sprague
595D474X9025T2T Farnell # 116-6814;

Semiconductors

Dl = LED, 3mm, red

T1-T8 = BCS56ALT1G, SMD, SOT-23, ON
Semiconductor {Parnell # 1 14-7782)

T9,TH3 - 2N7002, MOSFET, SMD, SOIC,
Texas Instruments Farnell # 102-1754

SCI r lC2 = TLG71CD, SMD, SOIC, Texas In-
struments {Parnell # 958-9449

Miscellaneous

K1,K2,K3 — 3.5mm jack socket with 3
con teds, Schurier R36310QGG Farnell #
149-933)

Si, 52 — 5P5T switch, angled pins, PCS
mount, height = 12.7mm, C&K7103MD9
AV2B8 (Farnell # 957-5510;

BT1 = 9V battery wiih clip-on lead

K4 - 2-way PCB pinheader

Case with battery compartment, e.g. BC2,
Farnell #223-554

PCB, ref. 0602374 from ThePCBShop

44

elektar eledianlcs - 2/7007

ing the resistors for switches SI and S2
(R12. R13, HI 5, R34. R35, and R37J: sol-
der only the ends of these resistors that
are not connected to the corresponding
svjitches* The other ends will be sol-
dered when you fit the switches to the
board. If you solder them before you fit
the switches, the holes may be filled
with solder.

Be sura to do a neat job of soldering,
since many of the solder pads are
close together. If you etch your own
PCS. be sure to make the through con-
nections between the top and bottom
sides carefully and avoid making any
shorts, which would be difficult la hud
later on

Enclosure

Once the circuit board is finished and
you have checked that it works prop-
erly. you can fit it in the enclosure with
the battery 7 compartment. Make holes in
the bottom part of the enclosure for the
input and output connectors and the
two switches. The top part must have
holes for the two potentiometers and
the LED. which adds a bit of flair to the
top of the enclosure ia square or rectan-
gular LED is a good choice here, with
the leads trimmed to the right length).

Putting it to use

Alter you're satisfied that the pream-
plifier is working properly you can
start using it Ail you have to do is to
connect two microphones to the input
connectors (K1 and K2) and connect
the output co the line input of your MP3
player, and you re ready to go. Use a
length of screened stereo cable for the
connection to the MP3 player.

Here's to good recordings!

\ Some MP3 players \

! with audio inputs j

i i

I Creative: I

I Zen Nano Plus i

I Packard Bell: I

I Audio Dream Colour I

g IRiver:

I T20 and T30 series i

I Samsung:

1 YP-ST5, YP-T6 and YH-925 series I

Measured results

Due to the very low input levels and the fan ihat it was not possible to product; ms neces-
sary levels directly using the available signal generators, we made an attenuator cable os
shown in Figure 5*

Characteristics:

Attenuation: 2000
(66 dB)

Output impedance:
680 Q

(nearly the same as a
dynamic microphone)
Preamplifier operating
in differential mode

figure S*

Sedrkal ding rant of the
attenuator «tk

Selling 1: Maximum cam = 1 dB t 66 dB — 67 dB. This is nearly the design, value of 70 dB.

Lo wer -3-dB point: 50 Hz

Selling 2: Maximum gain = -8 dB + 66 dB = 58 dB. This is nearly the design value of 60 dB.
Lower -3-dB paint: 50 Hz

Setting; 3: Maximum gain = -1 8 dB -t 66 dB = 48 dB. This is nearly the design value of 50 dB.
Lower -3 dB paint: 50 Hz

The upper -3 dB paint is above 1 00 kHz -2 dB at 100 kHz

INPUT JKJC*

Results

The three curves correspond to the three settings of switch 51 .
Measured results:

Noise and distortion

The noise and distortion figures were measured by the author. The results we obtained with
our awn analyser .Audio Precision, are nearl, the same.

Results

Swrtdi SI

cl 1 kHz

L

[dSV]

Measured

gain

5/H

THD

Output
noise level

Input
noise level

Gab mar

-1

0

67 dB

57 dB

0.1 2 : : 3

-57 dB

-124 dBY

0.63 1

Gainm-Djcn

+8

0

58 dB

65 d8

0.12%

-55 ii9

-123 dBV

0.71 pV,4

Gain mini

+18

0

43 cB

72 dB

fl.12%

-72 dB

-1:05 BY

Distarsion 0.12% of = Qd BV

0 * 04 % at V &j} = lOdBV

figure 6.

The results measured by ths
author are vary dose la our
measured results.

2/2007 - elstitorelEdittiia

45

HANDS-ON

CPLO

Horst-Walter Granitzki

A fair number of radio-controlled docks have appeared in Elektor Electronics but none before like
this. What makes it unique is the use of highly flexible CPLD technology to decode the signals.
Despite its complexity, our straightforward instructions will make sure that even beginners make a
first-class job of this design.

A dread of complexity is entirely hu-
mein, as is fear of the unknown, if you
haven't encountered CPLDs before,
you may not be happy to hear that
CPLD stands for Complex Program-
mable Logic Device. This time you’ve
nothing to worry about, however. The
article describes a familiar application
— clocks controlled by radio time sig-
nals — and you'll be able to exploit the
power of CPLD chips without needing
a higher college education or learning
Hardware Description Language.

The first DIY projects for radio time
clocks used vast numbers of chips.
They were veritable *TTL pits' — and
“money pits' as well. Far less of an un-
dertaking is this new approach using
a single CPLD chip to handle the many
logic functions. In line with projects
published previously in Elekzor Elec-
tronics we have once again chosen a
MAX7Q00S from Altera for our CPLD
[Ij. Tiie MAX— plush development soft-
ware [2j that you can download free

gives users by and large a free hand in
allocating the input /out put pins, ena-
bling us to set our the circuit described
here on a single-sided printed circuit
board (PCS) without the need for wire
links.

Our radio clock consists of just a re-
ceiver module for the DCF transmit-
ter (see footnote), some TCs for pulse
preparation and supporting the CPLD
chip, which itself decodes the time-
code pulses and controls the display.
Also included is a brightness control
for the display using a photoresistor. A
serial interface for connecting to a PC
is offered as an option.

Signals

The transmitter DCF77 located at Main-
flingen near Frankfurt am Main in Ger-
many radiates coded time and date sig-
nals on the frequency 77,5 kHz. These
signals are available, free of charge, at
just about everywhere in Europe that

Elekzor Electronics is read.

Coding of the DCF timecode signai is
achieved by reducing the transmitter
power by 25 per cent for either 100 or
200 ms, with the 100 ms pulse repre-
senting logical Low and the 200 ms
pulse standing for logical High, This
modulation takes place at the start of
each second with the exception of the
59 Th second, which is how the start of
each new minute is indicated. This se-
quence of digitally coded data contains
the time of day — and the current date
(including the year) — for the minute
that follows. In this project we are in-
terested only in evaluating the code
contained in the 21 s * to 34 th seconds
(see Table 1).

At ranges up to around 500 km from
the transmitter a low-cost receiver
module about the size of a matchbox
gives adequate reception; it consists
of a small ferrite rod antenna and a
tiny printed circuit board. These mod-
ules are available from some electron-

CPIDs in a nutshell

CPLDs ore programmable logic devices that share architectural features with field -program-
mable gate arrays FF 3Asl one programmable array logic: PAL . CFlOs use non -volatile
mem apy and do not rely on an external ca n fig u rat cars ROM, enabling them to function tm-
“edintely on s, stem srac-up. T n=, contah an immense number of gates enabling idem to
handle moderately ccmp Leafed data processing operators.

Table 1* Coding of the DCF Signal

Number of
seconds

BCD code

21 ... 24

Mi nates -units

25 ... 27

Minutes-tens

28

Parity bit

29 ... 32

Hours-units

33 and 34

Hours-tens

46

elchar ctevamts - IfMl

I**

1

Figure I. Raw da Ed from, ihe DCF receive; module needs to be processed before
the CPLD can get la viork on it. The CFiD aka take* (ore ol the display

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2 2007 - eieklar tkctionia

47

HANDS-ON

CPLD

Figure 2. This pulse diagtom Illustrates haw lh= preamplifier forms the pulses (see toil}. MF represents the 150*ms pulse- MPD is the
P rc d-jct of ihs Missing Pulse Dele-dot

ics mail order firms, including Conrad
El ectromc s ( \ vww. com ad-direct . c a. uk ) ,
part number 641138 - 62. It's advisable
to put this module in a small plastic
box, ideally fixed firmly in place with
sticky foam pads, glue or potting resin,
to protect it from harm. TV receivers,
poorly screened computers, electric
motors and suchlike can all interfere
with reception of radio timecode sig-
nals. so it makes good sense to con-

nect the receiver module to the clock
using a cable of adequate length (for
example microphone cable with two
conductors and a screen) to place it
outside the interference zone. Moving
it six feet or so will often turn marginal
reception into rock- solid operation. At
greater distances from the transmitter
or in poor reception areas (screened
mountain valleys for example) a spe-
cial outdoor antenna can be bought

— at a price.

The ferrite antenna should be arranged
broadside on, so that its long axis is
at right angles to the direction of the
transmitter.

Pulse preparation

In order to process the raw data in the
CPLD the information needs to be pre-
pared' first. Of the various DCF receiver
modules available, some invert the sig-
nal whilst others do not. The necessary
decoupling and inversion (if required)
are handled by IG2 (74LS14). as shown
in the diagram at Figure 1.
Discriminating between LOW (100 ms)
and HIGH (200 ms) pulses is ihe task
of monostabla IC1 (74LS122), which
should be adjusted for a pulse dura-
tion of 150 —10 ms. A value of 10 pF
for C 1 and 1 kQ for R4 together with
33 M2 for R5 will achieve this as a rule,
but if not, you should make changes
to R4 and R5. Tn the CPLD the rising
flank of me DCF signal shifts the exist-
ing logical level of the inverted mo nes-
table signal into a shift register and in
this way converts the time data from
pulse -length format into binary-coded
decimal (BCD) code.

The dual timer iC4 (NE 556) has the fol-
lowing functions. One hall operating
as a missing pulse detector 13), recog-
nises the absence of pulses on the 59' 15
second. The other half is triggered by
the inverted output signal from the first
section and produces a short RESET
pulse, whose rising edge signals the
beginning of a new minure. The values
given for C6/R8 and C4/R7 should pro-
duce guaranteed operation. Toe pulse
diagram clarifies the relationships (see
Figure 2).

Brightness control

The brightness control uses an ME 55 5
timer IG (IC5 on the circuit diagram).
The photoresistor PHI (type LDR
9060) has a resistance or a few kilo-
hms in brightness but up to 10 MO in
darkness The timer IC converts this
change in resistance Into a pulse- width
modulated (FWM) signal that switch-
es the elements of the seven-segment
display on and off in rapid sequence. In
this way the 'on time is about 20 per
cent In darkness and approaches 100
per cent under bright conditions (with
trimmer R26 set at 0 Q).

The value of 470 kQ for resistor R 17 de-
termines the minimum ‘on time dura-
tion and if increased to 1 MQ, the ‘on 5
duration drops and with this the bright-

ry • r --- k This circuit is implemented inside fhe CPLD chip and looks after further signal processing and contra El ing five display

48

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Figure 5, Setring out the J ccnn*ilimj link 1 required. This is destribed slfp^^atep in iheteit.

ness of the display to around 10 per
cent. R17 cannot be left out altogether
as then the frequency of the PWM sig-
nals would fall too low in darkness and
the display would flicker,

"i*

CPU) circuitry

The circuit shown in Figure 3 han-
dles further signal processing and
controlling the display. It needs to be
implemented in the CPLD using the
MAX-plusII development software {al-
ternatively you can obtain a ready pro-
grammed CPLD from the Elektor Elec-
tronics Shop as product no. 050311-31
|41). Here we shall follow the diagram-
matic method, which should be famil-
iar to most electronics enthusiasts and
produces usable results straightaway.
Run the software and at upper left on
the screen open a new file in Graphic
Design File format (Lgdf). To add com-
ponents you need to double-click at an
empty position on the circuit diagram.
An 'Enter Symbol* dialogue now be-
gins. From the Symbol Libraries select
the 'mf library by double-clicking ('mi'
stands for Megarunctions). A list of se-
lections opens, offering TTL building
blocks from the 74xx series. Choose the
74390 dual counter and confirm with a
click on 'OK'. The symbol for the dual
counter now appears on the diagram.
Repeat the same operation for a 7447
seven-segment decoder and place tills
to the right of the 74390. Shift one of the
two symbols, so that pins IGA and A
are aligned at the same height. To do
this click on the symbol and move it
with the mouse button pressed down.
To add the input signals DCF and
RESET double -click to the left of the
74390 and select ‘Input’ from the ‘prim'
(primitive functions) symbol library
and confirm with 'OK'. Add a second
INPUT in the same fashion. Move the
two INPUT symbols to place them at
the same height as 1CLR and 1GLKA
of the 74390. Now right -click the up-
per INPUT symbol with trie mouse. Se-
lect the 'Edit Pin Name 1 dialogue. PIN_
NAME is now iiig blighted in black and
can be renamed using the keyboard.
Give this input the name RESET and
confirm by hitting ‘Enter’, Repeat this
now for the second INPUT and name
it DCF.

Liiyinq out the links

To lay out the virtual tracks proceed as
follows. Click the capital A in the Sym-
bol column on the left-hand edge of
the screen. The mouse pointer chang-

es into a crosshair. Place the crosshair
on me unallocated connection symbol
of the RESET input and shift the cross-
hair, with mouse button depressed,
to the unallocated connection symbol
ICLR of the 74390. Immediately the
mouse burton is released a connecting
line is laid. Repeat this and link DCF to
1CLKA and outputs 1QA to 1GD with
the corresponding inputs of the 7447.
Your Graphic Design File should now
look like the one in Figure 4.

Hardly difficult, is it? You should now
save your project as a test, in the
Menu column go to File ® Project I
Set Project to Current File. A "Save As*
menu opens. Name your work file Radi-
ocIock.gdT and select as storage loca-
tion the direct on/ 'niax2work’ or some
other designation of your choice.

Then finish off the circuit by adding a
second seven-segment decoder the IN-

PUTS LAIuIP TEST and PWM as well as
14 OUTPUTS for the Seconds units and
the Seconds tens. Give the OUTPUTS
meaningful and unambiguous names.
Fields cannot be left empty.

Set out the connecting links until your
diagram corresponds to the one in
Figure 5.

This circuit is now in a position to
count down the Seconds pulses of the
DCF signal and shown them on two
seven-segment display blocks. The
RESET pulse resets the display to zero
at the beginning of each new minute.
The 59^ second is ignored on account
of the missing pulse, reminiscent of
the analogue slave clocks on some rail-
tv ay stations. The PWM INPUT is for
brightness regulation and along with
the EAMP TEST INOUT allows the
correct functioning of the display to be
checked.

2 2lD7 tItU: 1 G

49

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Figure 6, The FCB Is designed to simplify soldering. The CPLD is Ihs only surface-mount device used.

Decoding

Decoding of the DCF signal is handled
in two type 74164 ‘serial in r parallel out 1
shift registers. The leading edge of the
DCF signal shifts the current logical
level of the signal into to the register.
Since only data up to the 34 th second
is used for representing the clock time,
a D-type flip-flop (DFF) is included in
the circuit. The RESET pulse sets it to
HIGH and the '35^ Second pulse sets
it back to LOW. In conjunction with
the AND2 gate it passes clock pulses
through to the shirt register 34 times.
The ‘35 :h Second 1 pulse is produced by
gate AND4, whose inputs are linked
with 2QA and 2GB = 3Q T also IGA and
1QC = 5 of the 74390 dual counter.

A different arrangement of AND4
would allow data pulses following the
34'^ second to be evaluated as well, in
order to decode the year, month and
day of the week. A corresponding
number of additional shift registers
would be required then.

The remainder of the circuit is routine.
The type 7475 Latches are required be-
cause the display of hours and minutes
can begin only after the next RESET
pulse (remember, the DCF data pulses
indicate the number of the following
minute). On the other hand the seconds
can be counted down quite simply and
require no Latch, The eight ENABLE
inputs to the Latches here should be
linked to the RESET signal. The unused
4D data inputs of the Minutes tens to-
gether with the 3D and 4D of the Hours
tens should be linked to Ground.
Outputs IQ to 4G of the Latches are
each linked to the corresponding in-
puts A to D of four additional type 7447
seven-segment decoders. Their out-
puts GA to OG are each designated as
an OUTPUT (here too you should give
each OUPUT a recognisable and unam-
biguous name).

Almost there...

With this the circuitry is complete
and can be implemented ('fitted 1 ) in
a CPLD. For the seven-segment dis-
plays we have already used up 42 pins,
meaning that only an 84-pin IC comes
into the question. Go to Assign D De-
vice... on the Menu strip and on the di-
alogue box that appears un-tick ‘Show
Only Fastest Speed Grades'. In ‘Device
Family' select the type MAX7G00S und
as Device the EPM7128SLG84-15. In
‘Device Options,./ tick 'Enable JTAG
Support’ and remove all others. Con-
firm with ‘OK* and again OK'.

From the Symbol strip now select the

50

dekfor dedronrs - 2/2907

Compiler and click on the 'Start' button.
If everything has gone right up to now
the progress display will run through
without stopping and the message <
0 Errors 1 Warnings > will appear. The
circuit will function despite this warn-
ing. Using Assign I GlcbatPioject Log-
ic Synthesis... you can" make this warn-
ing message disappear if you un-tick
'Automatic Global Clocks Compilation
will now be carried out without any er-
ror and warning messages. Check out
the reports data produced by the Com-
piler by double- clicking the TpL symbol.
Among other thin g,*? the pin allocation
will be shown and at this stage this will
not match up with the PCS layout. Users
have virtually a free hand in allocating
pins to the INPUTS and OUTPUTS t pro-
lading the subtlety necessary to produce
complex circuits on single-sided PCBs,
For this project the pins are allocated
according to Table 2, To this end mark
the corresjDonding symbol on the dia-
gram with a right-click and in the con-
text menu select Assign > Pin/Loca-
tion/Gfcup... . The designation of IN-
PUTS and OUTPUTS is indicated at
< Node Name > . In held < Chip Re-
source > type in the desired pin
number at < Pin: >.

Pins can also be reserved for future en-
hancements, such as a serial interface.
For this add three totally unattached
INPUTS (without link tracks) on the
diagram and name these, for example,
‘Reserve T to 'Reserve3\ These three
pins are made tri-state, i.e. high- im-
pedance, and therefore can remain un-
switched on the PGB, OUTPUTS can-
not be reserved in this fashion but they
can be produced subsequently from a
reserved INPUT.

Now compile your project. There should
be < 0 Errors 0 Warnings > indicated
as well as a notification that three pins
have been reserved for future expan-
sion and are ‘tri-statedf On the Elektor
Electronics website [4) you can fin d ad-
ditional information as a gratis down-
loadable PDF ole; this includes a sam-
ple Report File with which your Report
File should correspond.

The September 2002 issue of Elektor
Electronics [5] includes a simple Paral-
lel /JTAG interface that is well suited
to programming CPLDs of the MAX-
7000SLC type if die JTAG plug connec-
tor K2 is augmented or replaced by the
appropriate PLCC socket.

Display details

To indicate die time we are using green
seven-segment displays with a charac-

Table 2: Pin allocations

Inputs

Pin

Seconds

Pin

Minutes

Pin

Hours

Pin

DCF

9

Seel A

69

Min! A

49

Hr! A

29

FEE FT

5

Seel B

70

Min IB

51

HrIB

34

HIGH/LOW

11

Sec 1C |

68

Min 1C

50

Hr 1C

30

LAMP TEST

75

Sec ID

65

Mini D

48

HrlD

28

PWM

12

SeclE

63

Mini E

45

HrIE

24

Reserve!

77

Sec I r

64

Min \ F

46

HrIF

27

Reserve2

79

SeclG

60

Min 1 G

44

Hr'C-

25

Reserves

81

SeelQA

52

Min 1 0A

39

HrlOA

20

Seel 0B

61

Min! 0B

41

HrlOB

22

SeclOC

58

Mini 0C

40

HT10C

21

Sec 1 0D

56

Min 1 QD

37

HrlOD

18

SeclOE

54

MinlOE

35

HrlOE

16

Seel OF

57

Mini OF

36

HrlOF

17

SeclGG

55

MinlOG

33

HrlOG '

15

ter height of 13 mm and a common an-
ode (see heading photo). With six dis-
plays we have 6x7 = 42 connections
to make to the CFLD. The data sheet
(6) shows the following recommended
current load values: 4 mA at TTL High
level and 12 mA for TTL Low level per
pin r with an overriding restriction that
the total current drawn from the CPLD
should not exceed around 130 mA. To
avoid misoperaiion this must be taken
into account when setting the values
of the series resistors.

The maximum current draw occurs
when all 42 segments axe illuminated,
which happens when LAMP TEST is
invoked. In normal operation a maxi-
mum of 39 segments are lit. With an
operating voltage of 5 V and a voltage
drop of 2 V in the LED segment the

necessary series resistor per segment
is calculated as follows:

E = [(5 V - 2 V) / 0.13 )) X 42 =
969.23 Q

To be on the safe side we would use
the next largest value of 1 kQ, for
which arrays of seven resistors in DIL
form are available, making construc-
tion extremely straightforward. Natu-
rally conventional resistors could also
be used.

Through each segment we now have
flowing a maximum of

(5 V-2 V)/ 1000 - 3 mA

At first this might seem rather low, as
the seven-segment displays are de-
signed for 10 mA, In practice, howev-

* COMPONENTS
! LIST

I

| Resistors

R1-R4,R22,R23 = Ik Q
I R5,R6 = 33kQ
R7 - 9km
I R8,Rl6 = 10GkQ
j R9 - 22Q
1 R1G,R20,R21 = 2kQ2
I Rl 1 -R15,R25 = 1 kQ 7-wcy SIL array
R17 = 470kQ
! Rl S.Rl 9 = 22LQ
R24,R27 = lOkQ
R26 = 100kQ muhsium preset
| PHI == LDR 9060

| Capacitors

C 1 ,C 6 = 1 0 J/F 1 6 V radial
I C 2 .C 3 ,CII = TQnF

C 4 ,C 7 ,C 8 ,C 9 ,C 1 G,C 12 ,C ! 3,04 =

I IQOnF
, C 5 = InF

1 C15 = 47G/iF 16V radio!

Semiconductors

DLD2 = 1N414S
Tl - BC557B
T2 J3 - BC547B
IC1 = 74LS122
IC2 = 7 4 IS 1 4
!C3 = NE556

IC4 = EPM71 285LC84U5, programmed,
order code 05031 1 -31
IC5 - NE555
IC6 = 7805

LD1-LD6 = SA52-1 1GWA {7-segment dis-
play with 90- degrees socket

Mis cel landaus

K1 — 3 -way SIL pinheader

K2 = 2-way SIL pinheader

K3 — 4-way SIL pinheader

IP I — jumper

JP2 = 3-way jumper

DCF77 radio tlmecantra! receiver module
(see text';

JC sockets

84 -way PLCC socket

Enclosure Eurabox type KGB 13

PCB, ref 05031 1-1 from v,ww4hspcbshop.

i

1

i

i

i

I

I

i

i

i

I

i

i

i

t

.i

J/2007 ■ tM.tor eWnwia

51

The cayvhoir

Dr Horsi-Wolter Gramtzki spends his spare time on electronics, mainly on gadgets to use
around the home and also docks using Nixie tube displays. He designed his first circuits
with TTt ICs towards the end of the I 970s but today he prefers using CPLDs. You
can contact him by e-mail oi Ho rst@GrQnitzki.de

er, the
value

works out fine
for a desk clock.

Anyone requiring a
brighter display must
fit dedicated seven-seg-
ment decoders in the tra-
ditional maimer. In this case
a low-cost EPM7G645LC44 can
be employed in the circuit. If the
clock is required to display the year,
month and day of the week as well as
the time, at least six more displays
will be necessary with then 12x7 —
84 connections in total. This too can
be realised with the EPM7128SLCS4
on the basis of this project, if the sev-
en-segment decoders are left outside'
the CPLD.

Construction

The PGB has been laid out intention-
ally to make soldering simple (see
Figure 8). Apart from the CPLD it-
self. which fits into a socket with pins
1.27 mm apart, there are no SMDs. All
tracks have been designed to have
sufficient width to allow constructors
to etch their own single-sided boards
(no hair-thin tracks that disappear dur-
ing the etch*). Take special care while
drilling the 84 holes of 0.6 mm diam-
eter for the Plastic Leaded Chip Car-
rier (PLCC) socket. They must line up
exactly, at the correct distance apart,
otherwise you will not get all 84 pins
to pass through properly.

As wire links are not used It doesn’t
matter which components you fit first.
The ideal power supply Is a small 9-
V plug-in ‘wall wart* device that can
deliver 300 mA, if its output is not too
high, the heatsink beneath the voltage
regulator can be omitted. Do not use a
switch-mode power supply as its puls-
ing could interfere with your reception
of DCF!

The seven-segment display blocks are
placed in special angled sockets; sock-
ets are recommended for all ICs, The po-

si-
tion

of pin 1
should be
noted for the
mono st able 1C.

For our prototypes a
half-shell housing de-
signed for Eurocaid boards
was chosen, and since the PCB
is only 157 mm long, a suitable
window of clear acrylic could be ar-
ranged in front of the display.

The components around transistors T2
and T3 including the four-pin connec-
tor (with the exception of R22 and R23)
can be omitted if the serial interface is
not required. Provision is made on the
board for connectors to the power sup-
ply, DCF receiver module and the PC;
the actual type of these can be select-
ed according to your own preference.

Commissioning your dock

It's best to test the populated PCB in
stages. With the CPLD and display not
yet installed the current consumption
should be in the region of 30 mA P and
around 85 mA with the CPLD. Now
plug the display devices into their
sockets and link the jumper JPi (Lamp
Test), Each of the displays should now
show ‘S' and the current drawn should
not exceed 200 to 220 mA. Experiment
a bit with the photoresistor; when it
is covered current consumption should

go down. Now adjust the spindle trim-
mer next to the photoresistor so that
the display is clearly visible in well-lit
sunoundings.

Next, connect the DCF module to K1
(check polarity: DCF signal goes to
Pin 1 of IC2). Jumper JF2 enables you
to select whether the signal is inverted
or not. The seconds should now count
down. If this does not occur it may be
that your receiver module is not deliv-
ering a proper TTL-ievel signal to the
input of the 74LS14. In that case the
mini-circuit in Figure 7 will assist (for
convenience the components can be
soldered directly onto the PCB of the
DCF module). Incidentally our CPLD
will not be overexerted by the task im-
posed by this circuit. A practical ex-
pansion would be an extra output in
serial interface format, for communicat-
ing with a PC for example.

E5?3 th

DCF module

Vcc

Figure 7. In the even I !hnl your mcdule doe* m\ produce TTL-
levcl signals, Ihis mini clrcuil rill serf ihings ny[.

Web links

[1 j v/wv/.elek5or-electronics.co.ijk/DefQult.aspjt?fafaid=28&year=2004&month=2&art=51 71 2
[21 wv, Y/ r a lie ro . co m / sup po rt/ softwa re/ down lo od/s of-do .v n I c a d_ce nier_ him I
1 3] http : 7/fa cu s JL co m/ 1 it/d s/sy m Iinksa555.pdf
X a'vv. e l e kto r. cam

[5 j yAw/.elektor-sl ed ronlcs, co, u k/Defa u Ifa s px?ta bs d — 2 S&y ear — 2002 &man1h= 9&ari = 507 45
16] v.-w v. a l terc .co m /I rt er a tu ro.- 'd s, m 7000. pd F

[ 7] v. ■ ,% ■ : h. w -serve r. co m - a o cs / 'defat. h I m I

(8] http:,'. : en , v*ikipedia.org/', viki/ D CF77

52

d elder efetfronics - 2/2007

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Take out a free subscription to
E-weekly now

Do you want to stay up to date with electronics and
computer technology? Always looking for useful hints, tips
and Interesting offers? Subscribe now to E-weekly, the free
Elektor Electronics Newsletter.

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53

TECHNOLOGY

INSIDE OUT

Fons Janssen - Maxim/Dallas Benelux

If is almost unbelievable: £5 for a digital multimeter with several extra functions and a set
of leads. Surely that isn't enough to manufacture a decent piece of equipment? To find out
how useful such a multimeter is and how accurate it is, we bought a cheap multimeter and
gave it a thorough investigation.

You often see them in the £5 box near the checkout at
Wallmortfish) outlets and builders' markets: multimeters
that appear to be able to measure everything. Voltage,
current, resistance, diodes and transistors; and oil that for
only £51 You can t help but wonder how they manage to
sell such an item for so little money. More importantly, it

would be interesting to know how accurate such a meter
was and if if would be suitable for use in the lab or only
for general use around the house. To find the answer to
this question the author took a great financial risk and
bought a meter in order to examine it closely.

Circuit diagram

Ar first sight the inside of the meter appears very straight-
forward. On the component side of the double-sided PCB
we see one 1C, a Few capacitors and resistors, a diode,
a fuse, a preset and a buzzer (refer to the photos in Fig-
ure 1), On the solder side we find the connectors and
contacts for the function switch and the LC display (lb).
The most ingenious parr is the rotary switch. This consists
of six slideaontacts that are mounted on the underside of
a plastic knob (lc), and another set of contacts spread
□ long 1 1 concentric rings on the PCB. This switch is used
to select a completely different configuration of the circuit
for each of its 20 positions.

The complete circuit diagram for ihe multimeter is shown
in Figu re 2* Broadly speaking, the circuit can be divided
into three sections:

• The function switch that selects the right circuit configu-
ration For Ihe required measurement.

® The voltmeter, built around an ICL7 106-type chip,
which takes care of the actual measurement and also
drives the LC display,

• Two ladder networks consisting of precision resis-
tors, which ore used to scale the input signal or act os a
reference.

Figure 1.
Th“ bnrdware of lbs
multimeter:
q) Ih&tase vjilh iis rear
cover remtiied, b] the PCB
from ibetronl, c) tbs rotary
sYiiifh wilfi six wipers.

The six slide switches (5W1 to $W6j make up a single
rotary switch, which Is used to select the different con-
figurations. For each position of the rotary switch the
contacts of the slide switches are always in a single line.
For current and voltage measurements the input signal
is conditioned so that the voltmeter 1C receives a maxi-
mum voltage of 200 mV (V f _: — 100 mV). For a voltage
measurement the input signet! is first reduced In value by a
precision potential divider. For a current measurement the
current Is converted into a voltage by a second precision
resistor network. When measuring a resistor the voltage
across the measured resistor is compared with the volt-

54

eleklor etsdronres - ?/2GQ7

ai t$ ft) b 5

Fowecrf

age across a reference resistor that has the some current
flowing through it. The voltage across the reference resis-
tor then acts as V, sf for ihe voltmeter 1C, which makes the
measured voltage directly proportional to the value of the
unknown resistor.

Extra functions

The nice thing about this mater is that it also has □ diode
and transistor test. Well look into these functions in more
detail. The simplified circuit diagrams For these Functions
are show in Figu re 3 and 4. For the diode test, 1C 1
sets V+ about 3.0 V above ground (note that the battery
-ve isn't connected to ground). When a diode is con-
nected to the meter a current flows through the series con-
nected R38, R39, R20 and the unknown diode. Assuming
a working silicon diode, it will have a voltage drop oF
about 0.7 V r which leaves 2.3 V across the resistors. The
current through these will then be approximately:

2.3 V/( 1 00Q+900Q+1 300Q) = 1 mA.

The voltage drop across R38+R39 is then about I V, which
is used as the reference voltage for the voltmeter. The volt-
meter shows the diode voltage using a ronge of 2 V. If a
voltage of about 0.7 V is measured you can conclude [hot
the p-n junction of the diode is still functional. 3f ihe meter
sees a voltage of less than 1 00 mV ll will sound a buzzer.
This continuity check is built into the voltmeter 1C.

The transistor
test (Figure 4) is just as
straightforward as the diode
test. When an npn transistor is
placed correctly into the test socket a current will flow Into
the base through R24. The size of this current is:

Vy /{R* + R2I 4 R22 + R24) « (3 V-
0,7 V) / 220 kQ„ IQ pA.

The voltmeter measures the emitter current via resistors R^
+ R21 + R22:

Figure 2.

CiKuil diagram forthe
muEtimefet

2/2907 - i’rfttor eScdramcs

55

TECHNOLOGY

INSIDE OUT

X = x 4 x 1 0 5 = /iij;£ x 1 0 5 x 10^ = /ifp!

For □ pnp She calculations are almost identical, except
that 4 15 replaced by / c .

Accuracy

The accuracy of measurements is different for each func-
tion. According to the manual it is ±0.25% of the full
scale at 200 mV ± 2 digits. For the other DC measure'
ments it is ±0.5% or the measured voltage ±2 digits. At
first this looks to be fairly accurate, but appearances can
be deceptive. Because we have a 3.5-digit meter, the
influence of these ±, 2 digits is much bigger than the per-
centage of the measured value, especially at lower input
voltages (compared to the full scale value]. In Figure 5
is a graph of the measurement error as a function of the
measurement voltage. As a comparison we've also shown
the measurement errors for a professional 5,5-digit multi-
meter (3 4 405 A], which was made available by Agilent
Technologies for use in preparing this article. From the
graph it is dear ihat the effect of the ±2 digits is greatest
at the lower end of each range.

That covers the specification. But how does the meter func-
tion in practice? To find out, we measured several voltag-
es with both the low-cost multimeter as well as the profes-
sional Agilent 344G5A multimeter. To keep things simple,
we’ve assumed that the Agllent-meter showed the ’correct’
value and that any differences on the low-cost meter were
due to the errors of this meter. The results of these meas-
urements are also shown in Figure 5, We con see that the
values fall well within the stated specifications.

We obtained similar results for current and resistor meas-
urements, With these the measurement error also stayed
within those given in the specifications.

W = / e x10Q

This voltage is measured using a reference of TOO mV
and the result is shown svlthout a decimal place. This
means that the value shown (X) Is equal to:

V^/0,1 mV - l 5 x 10Q/GJ mV- Lx ]Q5

Since h F£ \J 4, It follows that:

Figiir? >, The measurement error os o function of the input voltage for a cheap meter and o professional melee

Conclusions

From these measurement results sve can conclude that ihls
isn't □ bad little meter. For an electronics hobbyist just
starting out we would recommend It, especially ot this
price. However, it isn't clear what happens to ihe accu-
racy in the longer term. The specifications stated fhot the
given accuracy is guaranteed for a year, after which you
may have to calibrate ihe meter, If this meter were used
in a lab environment we would certainly recommend that
it 1$ calibrated on a regular basis. For critical measure-
ments, where accuracy of the figures after the decimal
point is important, ihls meter would be unsuitable and a
professional meter is essential.

And finally, well show all She advantages and disadvan-
tages in o list, so you can decide for yourself if such a £5
meter is suitable.

Pros:

+ Cheap
+ Versatile

Cons:

— Limited accuracy

— Low input impedance (1 MQj for voltage measurements

— Low-cost build quality' e.g. a soldered fuse instead of a
fuse-holder

— No facility for computer controlled measurements

"o’ :

56

dsktor dcdmnks - 2/200?

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We've used nearly every I/O port of
the prototyping board at least once
in this FPGA course. We say 'nearly'
because we haven't used the Ethernet port up to now. The final instalment of the
course sets this right with a full-fledged Webserver application.

The prototyping board has an Ethernet connector and as-
sociated Ethernet PHY. This makes it possible to connect
fhe FPGA to an Ethernet network, and ultimately to the
Internet.

Ethernet

An Ethernet network con be used to interconnect several
computers and other devices. The Internet is the largest
and best*knov/n example or an Ethernet network. This
article shows you how to connect the FPGA module to an
Ethernet network. This can be a small local area network
in you home, but it can also be the Internet.

has an Ethernet connector and Ethernet PHY r it rakes quite
a bit more than this to moke an Ethernet connection. The
task of the Ethernet PHY is fo transmit and receive data in
serial format according to the Ethernet standard.

Besides this PHY, you also need a media access controller
(MAC). The Functions of the MAC component are:

• automatic data flow control

O detecting data collisions and retransmitting data if
something goes wrong (CSMA/CD)

• adding a CRC checksum

Various sorts of logic in the FPGA module are necessary
for this purpose. Although the FPGA prototyping board

® adding a preamble on transmission and deleting the
preamble on reception

SB

deklor dctJroiiits ■ 2/2007

For the experts among our readers, this is Layer 2 or the
G5I model. Layer 1 consists of the combination of the
PHY, the transformer and the connector.

You also need a microcontroller with the right software to
add the TCP/IP protocol and the application to the sys-
tem, Just as in the previous instalments, we use the 151
core for th is purpose. '

The software Is based on the software for our MSC1 210
Webserver. We used the uC51 compiler and associated
TCP/IP stack to compile the code. This compiler is avail-
able from Wickenhauser (see Inset).

MAC

The media access controller (MAC) comes from
vAvw.opencores.com, and It is svritten in Ver-
itog. The MAC uses a 32-bit data bus, while
the T51 works with an 8-bit data bus. The
ethernet_verilog,vhd File was modified so these
two busses can be connected together.

The details of how this MAC svorks fafl outside
the scope of this article. In any case, you don't
need to understand the derails to use the MAC
properly. With the help of the software provid-
ed with the course, you can quickly write your
own applications for the Ethernet port.

First example

Our first example fex24) uses the T51 core,
the MAC core, and some peripheral logic.

The Ethernet core eats up a fair amount of the
scarce memory In the FPGA, so the maximum
amount of ROM available to the To 1 is 1 4 kB,
Th is is a ralher small amount of memory for
a Webserver. Among other things, the entire
TCP/IP stack, the control logic for the MAC
and the PHY chip, and the Webserver applica-
tion must all be fitted Into this 1 4 kB.

The RAM consists of an external SRAM IC that
is already present in the FPGA module. This
IC is connected to the microcontroller via the
wishbone bus. The memory layout is shown in
Figure I , The first 52 kB of RAM are provided by the
SRAM IC. Addresses OxDOOO through OxDFFF are re-
served for the Ethernet MAC, Finally, the remaining 8 kB
Is used as buffer memory for transmitted and received
data packets.

Now the FPGA prototyping board has to be connected to
a network. You can use a router or a switch for this. The
TCP/IP address of this application is set to a fixed value
of 1 92.1 68.0. 1. Ensure that your network is configured
such that address 1 92. 1 68.0, 1 is valid on the network.

If you use o router, ihe TCP/IP address of the router
must be configured such that the first three numbers ore
1 92 J 68.0, and the last number must not be 1 since this
number is already used by the FPGA module. If the router
has a DHCP server, you will have to adapt it to the new
TCP/IP addresses.

If everything goes the way it should, after you program
ihe FPGA you can use me web browser on your PC to
view the web pages in the FPGA by entering the follow-
ing address (URL):

http://192-168.0J

If this doesn't work, check the network settings of your PC
and router.

CODE

XRAM

OtFFFF

tfjtrrFF

S - E Ethernet RAM

OxEQDO

Etnsmet VAC

OxDOOO

52 kB

XRAM

0x3 7fr

14 k ROM

0x0000

OtVOOO

EC£-I-^

Figure I.

Memory layout for raampie

Even more

The Webserver of example 24 has just enough oomph to
publish a couple of HTML pages using the FPGA module.
This is rather on the meagre side, and it certainly isn't
what we really want. The limiting factor here is program
memory.

If you can expand this memory, you can then write more
meaningful applications for the Webserver Fortunately,
the FPGA module has some exlra RAM and flash memory.
If you use the Flash memory to store the program cade, in
theory you can use programs up to 128 kB in size. This
brings us up against a problem: you can program the
memory In the FPGA using Quartus, but you can t pro-
gram external memory.

Bank registers

Bankfn (0xF8)

Bit 4:1= VGA enabled; 0 — VGA disabled

(0x8 0 OG-Gx BF FR

Bit 5: 1 = SRAM always bank 0;

0 = SRAM depends on Bonk_S=l

BH 6:1= SRAM enabled; 0 = flash enabled

Bit 7: 1 = Ethernet disabled; 0 = Ethernet enabled

( GxDGOO-QxF FF F)

Bank_Sel(0xF9)

This register selects the current bank.

P « = H i a on 3 naa .-,oao -- t? .... D11

! Features of !

| example 25 ;

® 8052 controller running ot 25 MIPS ®

I 1

I •10-100 Mb/s Ethernet interface

I • 256 kB RAM (

] • 128 kB flash ]

1 • VGA interface |

^ • PS/2 interface ®

■ • Firmware updating via BGOTP

— — =* = ^ = = —^.*4

2,' 20-07 - elektor dearonks

59

HANDS

Figure 2.

Memory layout for example
ex?S v*hen the bootloader
is HOT executed.

CODE

XRA.U

OiFFFF

GkECHJQ

0*0000

Beol&sder

Code (RAMI)

32Sc Waitkrw
fcr

- E -. r“AV

Figure 3.

DHCP ser.er settings in, the
program tftpd 32 .

i , -“ — - “ — “ — — “ — - — “ — — -l

ific-5i ;

The software used in examples 24 and 25 was generated I
using the V/i eke nhd user £iC51 C compiler I

(vA'/w.wickenhde use r. de). I

V/e used this compiler on account of the TCP/IP stack that |

comes with the compiler. The free version of the compiler |

con Generate programs with up to 8 kB of code, which is not Jl
enough for our software. If you wish to modify ond recom- |
pile the sorTivare, you vvitl need the full version of the compift \
er. The price of the compiler was % 84.50 (approx. £ 59, at ]
the time of writing. §

■Up to now we have not been able to rind a suitable TCP/IP
stack for SDCC If at some point we manage to find on
open-source TCP/IP stack that is suitable for $DCG r we will
make this known via our FPGA forum.

Nalurally, we would also be grateful to hear about any suit-
able TCP/IP stock written by one of our readers or encoun-
tered by our readers somewhere on ihe Inierner.

Boo! loader

In example 25 (ex25), we connect the microcontroller to
the flash memory ond both SRAM chips. We also place
a boot loader program in the internal ROM. if you set
dipswitch 6 to ihe ON position and then reset the circuit
by pressing button 1, this program will run.

The boot loader uses the DHCP protocol to try to obtain
a valid TCP/IP address, such os the address of the router
or PC. IF this succeeds, if then uses the BOOTP protocol
to request data. The data that the microcontroller re-
ceives in response to this request is stored tn the external
flash memory.

if the system is started up with dipswitch 6 in the OFF
position, the content of the flash memory is copied to
the SDRAM (1C4 on the prototyping board). The pro-
gram code in the SDRAM is then executed. The reason
for copying the program code is that the flash memory is
relatively slow (access time 150 ns). The SDRAM has an
access time of 10 ns and Is thus much faster. The long ac-
cess time of the Flash memory makes it necessary to insert
three wail states for each read Instruction. As a result, ihe
microcontroller effectively runs at 6.25 MHz instead of
25 MHz. This restriction is not necessary if ihe program
code is executed from the SDRAM, so the microcontroller
is free to operate at full speed.

If is not essential to store the program cade directly in the
flash memory when you are developing new software.

For this reason, we added the option of storing program
code in external SRAM (IC4) instead of flash memory. To
do so, set dipswitch 7 to the ON position. The program
will then be executed From SDRAM after the firmware has
been downloaded.

RAM

The RAM memory Is also expanded in example 25. To
help clarify the following explanation, the memory layout
of example 25 is shown in Figure 2. This layout Is only
valid if the boot loader is not running. A different memo-
ry layout is used when the boot loader is running, so that
data can be written to the SRAM chip [IC4}.

The memory layout can be configured using two SFR reg-
isters: Bonk_En (GxFSj and Bank_Sel (QxF9).

Bit 4 or Bank_En determines whether VGA memory is ad-
dressable. If It is set to ] ", VGA memory can be accessed
in the address range OxBOOO-OxBFFF.

Bit 7 of the same register determines whether the memory
of the Ethernet interface is accessible as XRAM in the ad-
dress range GxDOOO-OxFFFF.

Bit 6 selects either flash or RAM for the upper 32 kB, if bit 6
is set to "0", Hash memory can be accessed in the memory
range 0x80QQ-QxFFFF. IF ihis bit is set to ' T, the content of
the SRAM (1C 3) is accessible in this address range.

Note that the VGA interface and the Ethernet interface
hove the highest priority. If either of these interfaces is
enabled, the associated addresses cannot be used for the
SDRAM or flash memory.

Bank-switching capability

is also provided to enable using ihe entire SDRAM ond
flash memory. You can use ihe Bank_Sel register to
choose which part of the flash memory or SDRAM Is se-
lected. In case of the flash memory, this register deter-
mines which of ihe 32-kB blocks Is currently in use. With
the SDRAM, this register determines which 64-kB block is
currently In use.

60

riskier electron m - 2/2007

Down to work

Thor's enough explanation - now let's try example 25 m
practice! Besides the usual software, you need one more
program file for this, which is named tfipd32. ft can be
downloaded from the internet free of charge (http://
lftpd32.jounIn.net). This program file contains a DHCP
server and a BOOTP server You need both of them in or-
der to load software into the flash memory.

To start off, you have to ensure that your PC uses a fixed
IP address. As already mentioned, we selected address
1 92. 1 68.0. 1 for this.

If you router has a DHCP server, you must disable it, since
only one DHCP server is allowed in a neiwork. If you use a
router, it must also be configured with a fixed IP address (In
our case, we used address 1 92.168.0.2 for the router).
After starring up tftp32 , you have to configure the right
DHCP server settings, in our example (Figure 3),
we reserved addresses 1 92.1 68.0. 1 05 through
1 92. 1 68,0. 1 1 5 for dynamic addresses. We also selected
file ex25.bin as the BOOTP file.

The next step is to use Guartus to configure the FPGA.
Make sure that dipswitch 6 is ON and dipswitch 7 is
OFF. After the configuration is completed, the boot loader
will start running and request an JP address. It will then
use BOOTP to ask far a program. You con see this in the
Log Viewer of the /ftp 3 2 window.

If everything goes the way it should, the IP address of
the FPGA will appear on the LCD screen. In our case,
the FPGA was assigned address 1 92.1 68.0. 1 07. Now
you can locate the FPGA module in your web browser at
address hftp://l 92. 1 68,0. 1 07. If your FPGA module is
assigned a different address, simply enter the correspond-
ing address in your web browser.

Pitfalls

The file that is sent vial BOOTP [the firmware for the mi-
crocontroller) must be a binary file. The pC51 compiler
will generate a binary file automatically if you use the
'make' files provided with the course.

If you want to use software generated by a different com-
piler, make sure that it generates a binary output file.
Most compilers can generate binary files. If you compiler
can't do this, there are several freeware programs avail-
able that can convert hex Files into binary files.

Conclusion

You can refine and extend the final embedded system of
example 25 to generate your own applications. The fea-
tures of this system are quite impressive, especially consid-
ering that the complete source code Is available in VHDL.
You can use this source code to enlarge vour knowledge
of VHDL

We hope this course has helped you carry out your first
practical experiments with programmable logic and
VHDL.

The course is naturally far from complete - the subject of
FPGAs and VHDL is so broad that you could easily write
a whole set of books about it. Nevertheless, we think the
course provides enough material - in pari because of the
numerous examples - to enable you to start developing
your own designs in VHDL.

We have set up a separate topic in the forums section of
our website so users of the FPGA module can share their

p “ — ■ <=r = a ‘= — — = = ^

• DHCP and BOOTP j

' The DHCP protocol can be used to assign dynamic address- I
l es to devices v/rth Ethernet ports. Each device in c network I
requires □ unique IP address so it con communicate with I
other devices. This can be achieved by manually assign- I

ing each PC or device a unique address. However, people
quickly realised that it would be convenient to hove IP ad-
dress configuration be handled automatically by a server. *

■ 1 he protocol for this is coiled the DHCP protocol. It requires

j a DHCP server. Most routers for home use hove built-in ■

| DHCP servers. |

I I

■ Another protocol that has been developed is the BOOTP

I protocol. This protocol makes it possible to boor PCs from o
j network If they do nor have Interna! hard disks. It a SOOTP
I request Is sent to a server, it uses the some protocol to sena .
I o small program back to the PC, The PC runs this program ■
I after receiving it. This program usually enables the PC to i
j continue siariing up from the server. This mokes It a lor easri i
\ er for system managers to supply new software to all PCs on |
| the network in a single operation or install updates. |

a In our example, we use BOOTP to send new firmware to the ■
| FPGA module This firmware is loaded into flash memory or i
I SDRAM (depending an the position of dipswitch 7] and then i
1 executed. i

experience. There's o good chance that you con pick up
new ideas there, and you can also ask other readers for
help wiih any problems you may encounter.

In any case, we hope you have a lot of fun [and learn
something) with the FPGA module!

350025-5,

p

Join the FPGA Course
with the

Elektor FPGA Package!

I

I

The basis of this course is an
FPGA Module powered by an
Altera Cyclone FPGA chip,
installed on an FPGA Prototy-
ping Board equipped with a
wealth of I/O and two displays
(see the March 2006 Issue).

Both boards ore available
ready-populaied and tested. Together they form a
solid basis For you to try out the examples presented
as part of the course and so build personal expertise

and know-how In the field of FPGAs.

Further Information may be found an the shop/kits &
modules pages at -vww.elektor-electronics.co.uk

L —

2/2007 - etektoi Electronics

61

HANDS-ON

SDRADIO

Burkhard Kainka

Until now panoramic display and
selectable bandwidth were features
found only on top range and
fearfully expensive!) shortwave
receivers. Realising these functions
in software makes it possible to
create a receiver for ridiculously
little money using barely any
hardware components. SDR and l-Q Mixers are the new watchwords...

Tills receiver is so cheap it’s an abso-
lute bargain — but with the inevitable
qualification. If (such a small word!)
you use a freeware program for the
software radio, if you build the mini-
malist hardware yourself and if the PC
(or notebook computer) used is already
paid for, then yes, you really can have
a new radio with all the luxury trim-
mings for virtually nothing. Naturally
the time spent creating it is not work,
just sheer pleasure. . ,

SDRadio

It s the Italian radio amateur Alberto
(callsign 1 2 PHD) whom we must thank
for the downloadable freeware pro-
gram SDRadio [1]. This PC program
teams up with the computer's sound
card and a simple RF front end to cre-
ate a magnificent shortwave receiv-
er for all modes from AM to SSB. Us-

ing the mouse alone, a range of up to
48 kHz can be tuned without even al-
tering the oscillator frequency. You can
see what's going on either side in the
adjacent frequencies and react flexibly
to interference, altering the receiver
passband as required.

The hardware we need is a so-called
I-G mixer (also known as a quadrature
mixer), which in principle is a direct
mixer but enhanced to be a dual-stage
mixer with phase-shift ed oscillator sig-
nals. In this article we shall use one of
these mixers in an experimental circuit
of our own design.

Theory (just a little!)

As well as the desired frequency, all
simple mixer stages also produce an
image signal' (mirror image) that fre-
quently requires a lot of effort to ni-
ter out and remove. However, this is

not the case for the l-Q mixer, which
in principle comprises two mixer stag-
es and looks after image signal sup-
pression itself. The concept can be ap-
plied to very simple receivers and is
particularly valid for software- based
receivers.

The three most commonly used receiv-
er types are the ‘straight* receiver, the
superfret and the direct mixer. In the
straight receiver a tuned circuit at the
input looks after all selection issues.
An example is the Audi on, which em-
ploys active absorption in the input
circuit to improve tuning selectivity. A
straight receiver of this kind does not
suffer from image signal problems but
offers rather weak suppression of ad-
jacent signals. The superhet is differ-
ent; here we have several intermedi-
ate frequency (IF) circuits achieving
good selectivity and adjacent signal
suppression. Unfortunately the image

62

elefcior electronics - 2/2007

signal still creates problems for us, A
superhet with an IF of 455 kHz has, in
principle, some secondary response
at twice the intermediate frequency
(2 T 455 kHz = 910 kHz). On medium
wave a preselector circuit is sufficient
to suppress this undesired response
quite adequately. However, many
shortwave radios exhibit a significant
image frequency response.

The direct mixer is an ideally simple re-
ceiver. Without the complication of an
intermediate frequency it mixes the RF
signal straight down to the audio fre-
quency stage. The process is used not
just with simple amateur radio receiv-
ers but also for equally simple DRM re-
ceivers, in which the ‘audio 1 signal is
in fact a 12 kHz IF. In both situations
the image frequency is so close to the
wanted one that we no longer have
any chance of filtering it out.

Figure 1 illustrates this problem in a
worked example, A signal on 3990 kHz
is to be mixed down to 12 kHz, The
mixer oscillator operates at 3990 kHz +
12 kHz = 4002 kHz. In die process an
image response arises at 4002 kHz +
12 kHz = 4014 kHz. We can only hope
that there is no strong signal present
at the 'wrong 1 frequency.

The solution to this problem is to use
two identical mixers instead of just
one. These are driven using the same
oscillator frequency but 90 degrees out
of phase. The same input signal then
produces outputs from the two mixers
that are phase- shifted 90 degrees apart.
The signals must then be phase-shift-
ed one more time (in Figure 2 tins hap-
pens in the phase shifter in rfre upper
branch ahead of the mixer) and then
summed together. Tills is where the
image frequency signals are cancelled
out, whilst the desired signal is ampli-
fied. This technique, seen here in the
I-Q mixer, is actually old hat and has
been employed, in the reverse direc-
tion, for a long time for producing SSB
signals. In that situation too the issue is
all about mixing signals without gener-
ating an image frequency (correspond-
ing in that case to the other sideband).
In amateur radio for instance this tech-
nique is known as the phase method

3990 kHz 4D14 kHz

4002 kHz

4(H)2 kHz

C-602M- 17

1. Imcge frequencies.

Figure • SSB generation using the phase melhcd.

RF LO

OFFSET 7 .2 KHz FH03A 7.2kHz

RECEIVED LO

1.6kHz
L P. FILTER

Reception path in fhs I hid jdieme*

2/2007 ' ekfctor electronics

63

HANDS-ON

SDRADIO

- Tesl build of ihe complefe receive l

and the problem with the phase method
is the difficulty of maintaining an entire
frequency band from 300 Hz to 3000 Hz
in phase to the same degree. In Weav-
er's so-called 'third method 5 two further
mixers are employed to sustain or con-
serve the phase-shifted oscillator sig-
nals [Figure 3). This method would for

example enable the construction of a
complete SSB transceiver without crys-
tal filters [2].

Meanwhile the prerequisites for the 1-G
mixer look ever more attractive, as signal
processing in software has made signifi-
cant progress. For our first experiments
there are some great programs such as

SDHadio and DREAM, All we need do is
provide two mixer signals, phase-shift-
ed 90 degrees apart, to the left and right
channels of the PC sound card. The soft-
ware handles everything else.

Circuitry

The simplest way of achieving the
phase shift required in the oscillator
signal is by digital circuitry (Figure 4),
Two D-type flip -Oops in a 74 AC 74 di-
vide the input frequency by four and
simultaneously produce output signals
phase-shifted by exactly 90 degrees.
Our clock source is the Serially Pro-
grammable Crystal Oscillator from
the March 2005 issue, hi principle we
could also use a free-running oscillator
on the four-times receive frequency but
then greater effort would be required
to achieve adequately good stability.
The mixer employed comprises four
analogue switches in the 74HC4G66
chip, which guarantees good synchro-
nism. between the two channels and
displays good signal integrity. Two an-
alogue switches axe combined to form
a changeover switch, so as to create a
balanced mixer. Figure 5 shows an I-
Q direct mixer for the frequency range

*5V

Fig A . broadband /eceEvet

64

e Settlor eletironiti - 2/20Q7

from around 500 kHz to 30 MHz.

A broadband transformer with
10 : (20^20) wire turns was wound on
a small ferrite core. The mixer itself is
followed by a low-pass niter. After this
a 20 dB amplifier increases the sensi-
tivity of the receiver. Figure 6 shows
a test makeup of the circuit (source:
www. e! ex s.de/ iq2 . htm ) .

The I-Q mixer provides image frequen-
cy suppression of up to around 40 dB. If
we link just one of the two channels to
the sound card the result is typical for
a simple direct mixer, as seen in Fig-
ure 7 A signal of 11 kHz appears at
both + 11 kHz and -11 kHz, With the
two input signals phase-shifted by 90
degrees the desired signal is boosted
and the image signal suppressed (Fig-
ure 8). With software alone a band of
48 kHz can be tuned in this way.

This simple receiver demonstrates as-
toundingly good reception results on
medium and short waves, in particu-
lar high sensitivity and good frequen-
cy stability, as well as amazingly sharp
selectivity of the kind that only soft-
ware can achieve.

Even greater improvements are possi-
ble, In order to avoid unwanted sec-
ondary response ids vital to use a good
sound card with an effective anti-alias-
ing niter. In very basic sound cards we
have observed that at a sampling rate
of 48 kHz signals above the theoreti-
cal limiting or boundary frequency of
24 kHz are processed with almost no
attenuation. A signal of 26 kHz then
appears at 22 kHz. With the I-Q mixer
this leads to stations outside the re-
ceive range popping up as phantom
signals, in this situation the only solu-
tions are a better sound card or a sepa-
rate anti-aliasing filter (the single -pole
low-pass filters used in the present cir-
cuit will not be adequate). You could

install for example four-
pole Butterworth filters
with a limiting frequen-
cy of 12 kHz but both
filters would have to
be equalised very ac-
curately which can be
achieved only by using
individually selected
capacitors.

A secondary weakness
of the simple circuit is
that the mixer also op-
erates on the odd mul-
tiples of the oscilla-
tor frequency. Since a
switching mixer also
exhibits principally
overtone mixing, using
an input band niter or
preselector would be
sensible.

DRM reception

The circuit described
here is also suitable
for use as a simple
DRM receiver, since
DREAM makes it pos-
sible to extract an I-Q
signal (Figure 9). For
this the parameter -C
3 must be entered. Us-
ing this simple circuit
and a long wire anten-
na numerous stations
can be decoded error-
free in the medium and
shortwave bands [3].
DREAM offers an ana-
logue mode as well and
works as a full-function
software defined radio
for AM, FM, SSB and
CW

Image frequency witfi only orae mim

Suppressed image frequency with two mixers.

r . : A DRM signal from Ihs I-Q miiei

Web links

[] ] h tip : // d igilonder.libefo.il/i2phd
sdradio/

1 l

12 1 wvav. b-koinko.de/drm. htm# drifts

1 1 3] vaw/. el exs.de/Iq 2. htm 1

1 I

f ]

I Information sources

Figures 2 and 3 ore taken from Philips
■ Application Note AN 1 981 New low-
power single sideband circuits,
j Further information on this subject
con be found here end a iso at way/.
onabg.com. library/onalagDialogue/
a rein i v es / 3 4 -03, u p con ve rsion fin dex. h tm!

! Weatherfax

l

The receiver j$ suitable not just for AM
und DR/.' but also far HF-FAX. As an
experiment the V.batherfax transmit-
ter DDH3 of the German meteorologi-
cal service was received on 4855 kHz.

As decoder we used a test version of the
universal receiver program JVC o mm 3 2
(vAvw.jvcomm-dej, The oscillator frequen-
cy was altered io 3875.5 kHz.

The illustration shows an extract ot the
weather mop received.

I* =e bz* t~l ra c=f ranntaianasi

n

1

I

I

I

1

I

1

1

I

1

1

1

1

I

I

I

? : 2D07 - dehor etectmmti

65

MODDIMG & TWEAKING

Jeroen Domburg & mijs Beckers

If we are to believe the Americans we should be prepared at all times for a terrorist attack.
In Europe we are heading the same way, as can be seen from various news flashes. The UK
has also adopted a threat level system, which indicates how worried the population should
be. This is all very well, but these types of indicator should really be utilised where they are
most effective: in the toilet.

Although the overage European doesn I normally suffer
from bomb attacks in the toilet, other types of attack seem
to be more common, mainly using biological gases. It
v/Guld be nice if there was an indicator thai prevented
you from opening the toilet door soon ofter somebody
else's visit, when you would be met a mixture of rather un-
pleasant gasses. The purpose of ihe Toilet Guardian is to
figure out what's been happening and Gn the basis of this
give a visual indication of the current terror level.

Terror level assessment

How can the air quality in the toilet be determined reli-
ably? Smell detectors do exist but they aren't cheap and

very difficult lo obtain, especially for the overage hob-
byist. We therefore need to acquire this information in a
different way. A light sensor turns out to be quite suitable:
Assuming that people turn off the tight afier their visit to
the toilet, it should be possible to make a good estimate
of Ins pong level from the time lhat the light has been
switched on. A timeout con be incorporated to deal with
those cases when people forget to switch off the light.
What is the best woy of showing the state of the ter-
ror level? The Americans decided they needed five
levels, represented by the colours green, blue, yellow,
orange and red. Three colours are enough for a toilet,
for which the traditional colours green, orange and red
come to mind.

Figure T, The circuit remains very staple, due to the use of a mifrofonfratjet

ek-itor efedrwiis - 2/2GQ7

About the author

Jercten Domburg h a student at the Samian Technical University in Enschede, the Net-
herlands. ierosn is an enthusiastic hobbyist, with interests in microcontrollers, elec-
tronics end commuters.

In ihb column he displays his person at handiwork, modifications and other
interesting circuits, which do net necessarily hove to be useful. In most cases
they are not likely to win a beauty contest and safety is generally taken- wrih a
gram of salt. But that doesn't concern the author at all. As long as the circuit
does whal it was intended for than oil is well. You have been warned!

Spider in the web

The circuit is controlled by a microcontroller (ATTi-
ny23 1 3). This keeps [he circuit very simple, os can be
seen From Figure I . The circuit requires a 12 V supply.
For which a standard mains adapter could be used. A
7805 provides the 5 V for the logic.

The microcontroller is the spider in the web of this circuit,
ft uses three MOSFETs to turn ibe lights on and off. The
loudspeaker is connected directly to two pins of the uC,
without the use of either an amplifier or D/A converter.

An LDR is connected to the analogue comparator input of
the uC. A preset is used to set the sensitivity. D1 shows
whether the microcontroller thinks that the toilet light is
turned on or off, and is therefore useful when adjusting
the preset. You should be aware that the IED could have
a delayed response of up to four seconds, which should
be kept in mind when you he adjusting the preset.

Al first sight the loudspeaker doesn't appear to be very
useful Without the use of a D/A converter or a proces-
sor that can hold a decent sound sample It surely can't
produce anything better than simple square-wave beeps?
However, you'd be surprised. The firmware can make the
loudspeaker produce a nice Ping! whenever the terror
level changes. We can compensate for the lack of a D/A
converter via the use of the PWM hardware that resides
inside the pC. The PWM Frequency h set for several hun-
dred kilohertz. The membrane of the loudspeaker can't
move that fast and will therefore take the average of the
PWM value. In this way we've implemented a component-
less 0/ A converter.

Simulation trick

We first need 1o find a way in which io generate the
sound. A simple square wave is ou! of the question
because it doesn't sound right and the 2 KB of Flash
memory isn't enough to store a sample of a decent
Ting!' sound. We therefore need to resort to a few tricks
to get the required output. If you open a wave file of a
TingF sound with a wave editor [in our cose: Audac-
ity [1]] and look or its spectrum, you'd see that a major
port of the sound is made by two frequencies: 771 Hz
and 3136 Hz t It comes 3n very useful that the higher fre-
quency is about Four times the lower one. The sound itself
gradually declines in amplitude over time.

Using this information we can write o compact program
that creates a sound very similar to the original, analogue
ping. The PIC program generates 32 samples for the two
sine waves and it outputs these from within a loop. An
additional routine uses some clever shift instructions to re-
duce the amplitude of the signal in 16 steps in half a sec-
ond. The resulting output produced by this code is quite
pleasing to the ear.

The rest of the firmware doesn't really do much. The main
part consists of a counter that increments once every two

Th= circuit h butt! oisio * piece of atrip board because only ± few tor.pc-
nenli are usfid.

An F FT grsph of a ding' sound shew; the contribution made by sff fre-
quencies* There ire three prominent peaks. Using sine waves for just the
first two peaks produces a good imitation of the souji d .

As aa interim measure, the prototype jvas fixed to the Wall using dud
tape, making it easier to cheek ihd the concept worked.

2/2007 - defctor dsdnmiu

67

HANDS-ON

MODDING & TWEAKING

The lighting is provided bj i number of b ri g.h I L E D 5 a which hive been
fixed to the cate using a hoi glue gun. U is of course also possible to use
1 CCFl or even = 12 V incandescent lamp.

This is whs! ihe finished indicator looks like. There are three separate
compartments inside Hie MDF bor. The front is made oui of plastic with
the printed Uttering just behind it.

seconds when the light is on, or which is decremented
every four seconds when ihe light is off. The fames at
which ihe terror level changes from one level to the next
□re stored as constants in the source code. This makes it
very easy to change the behaviour of the circuit to your
own preferences. As usual, the firmware con be down-
loaded free of charge from the author s website [2] or the
Ele k tor Electro n ics we bs fie [ 3 j .

The box

We used Google fo find inspiration for the construction of
the indicator hardware. We come across o fairly recent
adventure game that also had a "bathroom terror alert
indicator' os port of the game. We quite liked the word-
ing and the general look of this virtual indicator, so we
used this os a guideline. The indicator requires a box with
three comportments that can be lit up individually, reveal-
ing the text that's placed in front of them.

The box itself is made from MDF, with the front covered

by a piece of Plexiglas and an A4 transparency sheet,
svith the text printed by a colour laser printer A number
of bright LEDs provide the lighting. It is of course also
possible to use incandescent lamps or fluorescent lights in-
stead. Due to the popularity of PC case modding the cost
of the latter has dropped substantially. The current limiiing
resistors are only required when you use LEDs. You will
have to determine ihe values of these resistors yourself
because they depend on ihe type of LED used. The MDF
case can also be used to hold the loudspeaker.

Web links

[ i } DiidacityisoufGeforge.riei

[2j spriTe.5tucient.uKverite.nl — jeroen. project tvctsrrcr
: 3 J v. - w-v. e lekfor- efectnonics .co.uk

This is the final result. The electronics have been mounted intide the toi-
let to keep them out of sight.

The controller could alio drift other devices than the farror indicator
lights, You could for example hook tip a fen in parallel with the red, which
helps to remove the offending smells from the toilet ever quicker.

68

elektor elecfrcms - 2 ■ 2007

HANDS-Ot

DESIGN UPS

LDO Regulator

Stephen Bernhoeft

Recently the author had fa adapi
q standard circuit configuration
(which often uses an npn bipo-
lar) so os to operate as a low-
dropout (LDO) regulator. The cir-
cuit shown here uses that rarity,
a depletion-mode MOSFET to im
plemenl the LDO function

What to do when you have to
derive an analogue supply volt-
age (close to +5 V) From an
existing ’digital 5-volt rail, en-
suring sufficient decoupling be-
tween the two? One answer is
to step up and then use o line-
ar regulator to step back down.
However, if around 4,5 volts
will suffice then an alternative
is a home-made IDO regula-
tor. The circuit is usually a fairly
standard shape — typically an
npn transistor [with base-current

limiting resistor) is used. Initial-
ly, it would appear that this de-
sign suffices — after oil, the text-

books say the saturation voltage
rs around 0.2 V. Unfortunately,
this is no longer true when the

collector is tied directly to the
positive supply. An enhance-
ment-mode MOSFET suffers
similar disadvantages: with the
drain tied High you need great-
er than drain potential at the
gate to achieve law En-

ter that seldom-used beast — the
depletion-made MOSFET!

Depletion-made MOSFETS are
'on' even when V ps = 0 F and
you have to back-bias the gate
to achieve an increase in chan-
nel resistance.

In the circuit shown the BSS J 39
an NMOS depletion device op-
erates with the gate forward-bi-
ased. With a load of 10 mA,
the measured FET resistance was
38 ohms.

C6GE9C4I

i

Bi-colour LEDs operated by LDR

Ken Barry

The author thought it be nice to
render a number J 4 (his house
number) using a slowly changing
two-colour LED display.

The display shown here employs
an LDR which causes the LEDs to
dim during the dark hours and
light at slowly increasing bright-
ness with daylight The function
ensures the house number would
always be visible day or night.
The circuit diagram shows an
Qstable multivibrator T2-T3 com-
bined with switch able potential
divider T1 . The latter is switched
on ond off by an LDR and a
capacitor.

Assuming a supply voliage of
4.5 volts the circuit consumes

+4V5

r r

Ljf —

LET- ft,
353 * 34-11

about 80 mA to light 37 bl-coh
our LEDs of the three-pin com-
mon-calhade type. The LEDs used
in the prototype were supplied
by CPC/FarnefJ (http://cpc.far-
neSI.com) order cade LP00362.
All LEDs are connected in paral-
lel as shown in the schematic by
ihe dashed outline.

A 10-kQ resistor Is connected
in parallel with Ihe LDR (□ type
ORP12) to govern the threshold
level to a degree. You may want
to experiment with the value.

Pin Pilch 2,54mm

PIV Max. 5

View Angle 24

LP00360 LP00361 LP00362 LP00363 5mm (T1 ) tri-colour LEDs

Slum unlisted dear teas lEDs * Common calhode • Both diodes tonnetled gives third intermediate fdoor * low pavm consumption

Colour

Lurru Intensity (med) @ 20mA

If (mA) Max.

Min.

Max,

HE Red/Green

1 00/50

300/200

30/25

HE Red/Yellow

1 00/30

300/80

30/30

Green/ Yellow

50/30

200/80

25/30

Ultra Red/Green

300/80

700/200

30/25

2/2007 - eledronics

69

All information in this advertisement subject to change. E. & 0, E.

iTlmtan

1. monitor your fleet with GPS/GPRS/SMS

2. monitor your staff in any country

3. send messages to/from your people

4. monitor your machines wireless via internet

5. update machines worldwide with your PC

6. sufficient I/O for sensors etc.

7. i Button auto start safety device

8. guard properties via mini camera

9. unlimited applications possible

10. Dutch design

11. Dutch production and support

12. Satisfied customers:

IMTECH

DUTCH POLICE FORCE
PORTUGUESE FIRE DEPARTMENT
AGGREKO GENERATORS
SKYNET MOBILE
UK GOVERNMENT
MOTOROLA DUBAI
AFRICAN OIL COMPANIES
GERMAN ROADSERVICE
and many others worldwide

ijraceMt mini hrY camera
watches over your belongings
and transmits pictures via GPRS,
Watch them via your web browser,

Communicate in your car with the office or with
another vehicle via a.o. SMS with the TraceME LCD module
Secure your vehicle with the help of an iButton start.

A TjraceME solar version
can be supplied for situations
where no fixed power source

GSM A**

of organs,

Ambulances and other transports

Wireless distance control of

miniature cameras and/or
sensors via wireless
transmission.

ah SPflf R'3232-mferface
Climate control.

Busses, cars, lorries, taxis,
fire engines, river craft,
trailers (also on solar energy)

Various police services have
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TraceME modules +
cameras ip various countries.

Detection ofi temperatures during

Pilot/control your machines/pumps
etc. via the internet without the
help of mechanics.

signals whefjfdeviations occur,

HANDS-ON

E-BLOCKS

IF I o weed e from fife

As many of you have already discovered,
E-Blocks, along with programming tool
Flowcode, open up enormous possibilities,
though you still have to start somewhere. The problem is — where? The Flowcode CD-ROM
contains a very accessible course called Flowcourse. Now's the time to really make a start in
programming and transferring a project from the E-biocks environment into the real world!

Figure 1 . Description o! the light chaser in Flowcourse,

72

elector elscinmia * 2/7007

I Hot plugging !

The Win do -vs XP operating system copes perfectly with E-
blocks thanks to the USB link.

| We can also be thankful to Ihe designers of E-blocks far |

| powering the v.U'lt, - <og Ra'avsr r s interface via the USB bus. 1

1 This avoids problems -viffc disco fined ion ■reconnection with |

| the PC when ins power Is removed and applied again In J

I order to insert or remove ihe microcontroller or an exren- |

| sian cord, j

- _ - _ _ j

Install the software an the CD-ROM, accepting all the
m default options offered, in addition to Flowcode Itself,
you II be installing MPLAB, Microchip's assembler and
H2, C compiler. You will hardly notice these programs, since
Flowcode takes care of the interface 'transparently r as
they say.

Assuming drive D: is the CD-ROM drive on your compu-
ter, use your system browser to go to the directory D;\

W flov/course [), Open the page mainpuge.htmi

From this point on, we will assume that you've already fol-
lowed the beginning of the course, so you know roughly
how a microcontroller works and, in theory at least, how
It can be programmed to turn an LED on and off.

The Light Chaser project

Open the page Project I : Light chaser [Figure 1).

Here you'll find the description of one of the simplest
demonstration applications; on LED light chaser. We re
no longer talking about just turning on or off a single LED,
but a whole set of eight LEDs,

As soon as we start to bring this application into the reol
wort d using Flowcode , prompts and questions will pop
up so instead let's take look at the answers: no, there is
no bridge provided between this demonstration applica-
tion and the files in the Tutorial directory; no, the num-
bers used as filenames don't relate directly to an applica-
tion; and no. there isn't a file in the directory correspond-
mg to the application we're Interested in.

So we re going to use the Flowcode Editor to create, from
scratch, on application to maich the description. Let's get
into swing by reproducing the first flowchart — the one in
Figure 2.

Click on File, then New; after entering the type of micro-
controller used (here, o PIC 16F88}, you'll get on Editor
page with a program that has just two labels, BEGIN and
END (Figure 3).

To add symbols between the beginning ond the end all
you have to do is left-click on the selected symbol in the
left-hand column, then hold the button down and drag the
symbol into position (Figure 4}.

Right-clicking now opens a box where you can enter the
properties far the object under the cursor.

Here, well use English for the labels, though except for
keywords it doesn't matter what language you use (Fig-
ure 5) The software automatically sets the loop end tag
and gives it the same name as the star! tag.

1 Onwards io the micro

To check the operation of our first program, well hove to
transfer it into the microcontroller s program memory. But
before v/e get to that point, the flowchart first has to be
converted into o C-language program. Next, we need to
compile this C program into o form accepted by o pro-
gram assembler. Next, the assembly cade is translated

Into machine code (PIC in this case],
which is finally loaded into the flash
memory of the chip. The good news is
that you, the user, need not worry about
the detail of these operations, as the
Flowcode program automatically per-
forms them in the correct order when you
dick on Compile to PIC (Figure 6).

The program riming phase

The programmer used to copy the ma-
chine code into the microcontroller
memory is ihe mujipeogsav^^er card from
Elekfor's E-Blocks range.

It Is automatically recognised by the saft-
ware installed earlier. The microcontrol-
ler used here is the PIC 16F88, which is
more than adequate for the job.

The programmer reports that the opera-
tion was successful, and ihe program
runs Immediately (Figure 7). The report
tells us that the program only takes up
I I 5 out of ihe 4096 program words
available, Le. r less than 3%l
After this check on the PIC programming
sequence, you continue to drag boxes
into ihe flowchart (ond sometimes out
again!) until the complete program is
produced. The finished flowchart for the
last example looks like Figure 8,

Some more program details

The 'Shift box (Icon) may require a little
explanation. The action performed is ac-
tually no more than multiplication or divi-
ihere is no physical shifting as

ston

such. It s just an arithmetical operation,
because that's all a microcontroller can
do! tn any number system, multiplication
or division by ihe base Itself Is equivalent
to a shift-right or shift-left by one order
of magnitude. The binary system is no
exception fo this — hence by multiplying
the number COUNT by 2, we shift the
LED thai s on to the left, Y/hereas by di-
viding by 2, we shift it to the right.

You will note that the delay between
the steps is different from the example
and that the rise time is different from
the fall time. Sliding down the greasy
pole is usually Faster than climbing It!
You're quite free to reduce or increase
the lengths or the delays to suit your awn
preferences.

Figure 2. The elementarf program In the
Flomaune tutorial Wm going to k-
repioducing ihls slep by step,, before adding
Turlher functions lo if.

figure 3. Al ihe oulset, Ihe Rowtbarl has no rccre
Ihan these two logs, between which we' re going
lo be Insert a series of msliurEioni,

Figure ^ A righl click lets us access ihe Properties
of Ihe hot we\ejusl added.

2 2&07 - “leVter efetfronla

73

HANDS-ON

E-BLOCKS

figure 5. The Ptopaftercrttry bun — in practice,
these ate aiilhmeik operations.

figure 1 The Compile lo PIC iemmnrtd Haiti
the process of transferring the ffmrafenif info the
microcontroller's. program memory All assuming
that ihe type of m T croconf roller has been specified
using the Target PIC option*

—njsr. snG rerr*i3 Of,

LAI £l£ ■tf’AOSS .iiv j*

; c 4 Iz6 Eiiti c j

Figure 7. Prog jamming lakes only □ few seconds.
The chip memory tW\l has plenty ol spate felt.

As soon ns this menage pops up, your program
starts tunning.

X

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Figure 9. The application drctitt involves just o few components.

Undressing Ihe E-b!ocks project

Now that we've accomplished the program writing, debugging
and chip programming, it's lime to Iransfer the project from the
E-blocks environment into the real world, where it will func-
tion stand-alone”, hopefully! Your general method of working
should be lo use E-blocks to do all the program writing, testing
and debugging, and then 'move' the finished lot to o completely
separate board. As part of ihe approach, simply revert lo your
E-blocks system if errors are found in the standalone hardware
[and they will be found!] , or if users require improvements,
tweaking, extensions, etcetera. In this context, ihe program simu-
lation abilities of E-blocks will be particularly valued. You may
also Find that some E-blocks modules like the switch board or the
led board are only required for

In line with this method of working, we're going to breadboard
a self-contained circuit so as to free off the mu incogs a v.v.e= and E-
Blocks ifD 2 -oard for their original purpose of testing and develop-
ing programs.

The programmed microcontroller is pari of ihe targei circuit
shown in Figure 9. The breadboarded circuit may be produced
on prototyping board, a.k.a, 'perfboard', stripboard or 'Vero
boardd The author's prototype is shown in Figure 10* Track
breaks are made using a 4-mm drill bit fitted into a spare drill
chuck to act as a handle.

Naturally, the PIC microcontroller is not soldered in, but simply
plugs into its socket. The light chaser is powered from □ 5 V
supply.

‘ r ■7:5-1

r

Flowcode 3

Registered users of Flowcode 2,x versions are advised that
Flowcode 3 is now available from Matrix multimedia or
Elektor Electronics. Flowcode 3 is described in the December
2006 issue of Eiektor Electronics. The product may be ordered
from the SHOP pages at www.elektor-electronics.co.uk

L

Figure 1 The tighl spc! ot ogr those goes back
and tort h in Knl g h t ride r fashion, instead of
doing ihe single sweep of 3hs c rigir.nl program*
To do I his, it sequent together a "Push right'
loop with q 'Push fefl r loop, then goes Barit lo
Ihe start

Fig ,ra 10 The layout of the components on ihe
prototyping board largely fallows the positioning
in ihe drcuil diagram. The horiionfal lines ore
formed by ihe topper strips of the board, Ihe
vertical lines by the com parte nl lea di or pieces a I
insula ted wire.

i

74

dehor electronics - 2/2007

Elektor Electronics (Publishing)
Regus Brentford

Brentford TW8 9HH
United Kingdom

Telephone ^44 (0) 208 261 4509
Fax +44 (0) 208 261 4447
Em ail : s ales@ el ekto r-eleciru n ics. co, uk

Order now using the Order Form

in the Readers Services section in this issue

Step into the fascinating wor

microcontrollers

Microcontroller Basics

Burkhard Kainka

Microcontrollers have become an indispensable part of modern electronics.

They make things possible that vastly exceed v/hat could be done previously.
Innumerable applications show that almost nothing is impossible. There’s thus
every reason to learn more about them, but that raises the question of where
to find a good introduction to this fascinating technology. The answer is easy:
this Microcontroller Basics book, combined with the 89S8252 Flash Board project
published by Elektor Electronics. This book dearly explains the technology
using various microcontroller circuits and programs wriiten in several different
programming languages. In the course of ihe book, the reader gradually develops
increased competence in converting his or her ideas into microcontroller circuitry.

Contents of Starter Kit:

• 89S8253 Flash Microcontroller board
(ready-assembled and tested PCB)

• 300-mA mains adapter

• Serial cable for COM port

• Software bundle on CD-ROM £69.00

• Article compilation on CD-ROM US$ 112.5B

ISBN 978-0-905705-67-5
230 Pages
E18.70/USS 33.70

Flash

Microcontroller
Starter Kit

Elektor Hardware & Software

Step into the fascinating world of microcontrollers
with the Elektor Electronics Flash Microcontroller
Starter Kit. Order now the ready-assembled PCB
incl. software, cable, adapter & related articles.

Upgrade for Flash
Microcontroller Board

AT89S8253 supersedes AT89S8252

Enchancements AT89S8253 versus AT89S8252:

• 12 kbytes of flash memory instead of 8 kbytes

• Page Mode for faster programming

• Doubled processing speed using X2 clock option

• Power-on reset function and brown-out detection

• Supply voltage from 2.7 V to 5.5 V

INFOTAINMENT

RETRONICS

Jan Suiting

'Wobbulator', opart from a funny
word In oi will earn you not only
o good score bul also fierce dis-
cussions when ploying Scrabble,
refers to a test instrument for vis-
ualizing the frequency response
of fillers and IF (intermediate fre-
quency) amplifiers in receivers.

According to manual, ihe Insiru-
meat I hauled down from my at-
tic for this month's Ret r antes was
designed by Philips Telecommu-
nication to "adjust Intermediate
frequency amplifiers operat-
ing at 1 .5 MHz or 9.72 MHz .
Whereas most of today's per-
sonal mobile radio (PMR) equip-
ment hove first IPs or 10.7 MHz
or 21 .4 MHz, the use of 1 .5 MHz
and 9,72 MHz was common
practice in the 1950s and 1960s.
Crystal filters for these two fre-
quencies being unavailable as
well as unaffordable ci the time,
it was essential roc the IF pass-
band to be properly tuned as it
determined to a large extent the

receiver’s selectivity and FM dis-
criminator response.

Most PMR equipment of these
years was supplied with 'stag-
ger-tuned' muili-siage IF ampli-
fiers. Each L/C network in a fil-
ter or amplifier ,vas adjusted □
little below or above the centre
frequency' to creaie a flat pass-
band with the desired width (usu-
ally 100 kHz or so). In practice,
the IF amplifier in the engineer-
ing prototype was very carefully
set up to the highest standards
by adjusting the dozen or so
cores in the tuned L C networks,
all with the help of a wobbula-
ror and an oscilloscope. The ap-
proved filter response was then
declared ihe 'standard' and the
relative depth of each ferriie core
in Its coil former carefully noted,
Nexi the cores positions were
visually and manually 'copied'
on to the L/C boxes in mass-
produced amplifiers. In other
words, none of the IF amplifiers
that left the factory had been In-
dividual! y tuned for optimum re-
sponse — they were assumed io

function as closely as possible to
the standard, which can only be
upheld if you can rely an fairly
close tolerances on production
ond components used (in par-
ticular, the silver-mica tuning
capacitors). Poor show? Philips
got away with this quite well for
more than 20 years.

The 5FM1 14 00 shown Is com-
plete, original ond works a treat.
I hooked up an old oscilloscope
and attacked the stagger-tuned
1 .5 -MHz IF amplifier in my 1 953
5DR314 portable (see Retronics,
November 2006 io see If im-
provements could be achieved.
Adjusting inis 6-stage IF amplifier
Is great fun. To set up a virtually
flat possband of about 130 kHz
wide (± 66 kHz; with steep edg-
es (80 dB selectivity) takes about
half an hour to get absolutely
right. The improvement over the
stagger-tuned settings is dra-
mahe on the scope screen. In
practice, there's a higher and
steadier FM noise level as well
as slightly less distortion of the

received signal (probably due to
the discriminator being properly
driven now).

The 5FM1 14/00 also generates
marker pulses 20 kHz either side
of the centre frequencies. On the
first ten or so pages of the user
manual, the writer (or typist) insists
that an ECL80 valve is configured
as a 'flip-flap' for this purpose.
Then a text correction is seen on
page 1 2 and we read 'flip-flop' in
the remainder of the book.

This wobbulatar employs an un-
usual method of generating the
swept-rrequeney output signal
al 9.72 MHz. Basically, if Is ob-
tained from subtractive mixing of
1 1 .22 MHz and 1 .5 MHz quartz-
generated signals rather than
straight frequency variation at
an oscillator. The reason 1 guess
is that it was difficult to produce
sufficient 'pull' (of the order of
■±1Q0 kHz) on a 9.72 MHz crys-
tal without running into harmon-
ics or undesirable amplitude
variations.

Q75GJ3-"

Kk Ironies is a monthly column covering vintage elect ranks Including legendary Eleklar designs. Contributions, suggestions and requests ore welcomed; please send an
email io editor@olektoT.cam, subject: Re-Ironies EE.

76

e!flk tor elearania - 2/2DD7

PUZZLE

INFOTAINMEN

nexadoku

izzle with an elec' or ic to id

The Hexadoku puzzle for this month is yet again the perfect prompt to
start thinking about other things than transistors, microcontrollers or
software. Juggling hexadecimal numbers not only stimulates the brain but
may also win one of the prizes we've on offer. Join Hexadoku this month,
send us your solution and enter the prize draw.

The instructions for this puzzle
ore straightforward- In the di-
agram composed of 16 x 16
boxes, enter numbers such
that all hexadecimal numbers
0 through F [that's 0-9 and
A-F; occur once only in each
row, once in each column
and in each of the 4x4 boxes
(marked by the thicker black
lines), A number of clues are
given in the puzzle and these

determine the start situation,
Alf correct entries received
tar each month's puzzle go
into a draw for a main prize
and three lesser prizes. All
you need to do is send us the
numbers in the grey boxes.

The puzzle is also available
as a free download from
our website Magazine — IQ'ZC ->
February).

Prize winners

The solution of the
December 2006 Hexadoku

is: 87E46.

The E -blocks Starter Kit
Professional goes to:

Tim Parsanson,

Brandon (UK),

8

D

B

6

1

C

3

4

C

9

A

0

D

E

F

6

F

!! C

2

9

5

7

5

6

A

7

8

B

9

E

1

6

E

C

1

4

3

5

7

F

3

D

9

1

2

3

1

0

9

4

5

2

E

7

A

2

9

5 |

D

7

6

1

F

4

8

1

3

2

6

0

8

B

5

C

D

9

C

4

8

B

1

A

D

9

2

_8_

7 _

A_

3

5

0

D

2

5

"c"

9

A

4

F

2

1

F

3

9

6

7

1

D

E

4

B

5 !

C

B

E

3

6

8

D

i.Ci P ZZLasm

Participate!

,'SLjT so nhc-r. (tbs numbers in
rh^ grey boxes c, email fax or post to:

Elektor Electronics Hexadoku
Regus Brentford
1000 Great Wes! Road
Brentford TW8 9HH
United Kingdom.

Fax (-t-44)(G)2Q8 2614447
Email;

edjtor@elektar-efecfremc5.co.uk
Subject: hexadoku 1-2007.

The closina date is

1 March 2006.

“ : T T-=-" I" z _■ £-p=f !; =~z Z ftftS -J
-.* ■ c . i”bj r=££5 - r : :■

□=S£I'C.'3te3 tvt TS-uSES

An Ilektor SHOP voucher
worth £35.00 goes to:

Dmitry Kuznichov, Hopartim 1 1 SR :

Isolde Tietz, Darlington AUS;,
Nigel Gar ka -Pope, Oa* e, uk.

Congratulations everybodyl

Solve Hexadoku
and win!

Correct solutions received
enter a prize draw for on

E-biocks

Starter Kit Professional

worth £ 248.55

and three

Eiektor Electronics SHOP
Vouchers worth £35.00 each,

V/e believe these prizes should
encourage all our readers to
participate!

2 - 2 0j 7 - $*ektar electronics

77

■

ELEKTO

SHOWCASE

To book your showcase space contact Huson International lUi'ectia

Tel.

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Fax 0044 (0) 1932 364998

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Appears just like a serial port to both PC and
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your projects, or replacement of existing RS232

interfaces.

See our webpage for more
details. From £15.00.

BAEC

http: fba^.tnpiixom

The British Amateur Electronics
Club Archive Website. Archiving
extracts from 140- Newsletters fra m 1986-
2002. Currently have interesting and useful
selected articles from 12 Newsletters. Also a
section about built electronics projects with
schematics and photos. Pius useful info.,
downloads and links. NO ADVERTS!"

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Beta layout Ltd Award-
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offers prototype
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cost of the usual

CONFORD ELECTRONICS

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Lightweight portable battery, mains audio units
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Microphone, Phantom Power and Headphone
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EASYSYNC

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EasySync Ltd sells a wide
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* Low Cost Adapters for all
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* Single Site and Gang Programmers

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78

t'tkf-jr deifroma - 2 '2007

products and services directory

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Available from all Maplin Electronics stores and

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products and software such
as Oscilloscopes, Data
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VIRTINS TECHNOLOGY

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PC and Pocket PC based
virtual instrument such as
sound card real time
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multimeter, sound meter
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CD-ROM

USB TOOLBOX

This CD-ROM contains tech-
nical data about the USB
Interface. It also includes a
large collection of data sheets
for specific USB components
from a wide range of manu-
facturers. There are two ways
to incorporate a USB interface
in a microcontroller circuit: add
a USB controller to an existing circuit, or use
a microcontroller with an integrated USB inter-
face. Included on this CD-ROM are USB Basic
Facts, several useful design tools for hardware
and software, and all Flakier Electronics articles
on the subject of USB. £18.95 (USS 34,95}

Home Automation

This CD-ROM provides an
overview of what manufactu-
rers offer today in the field of
Home Networking, both wired
and wireless. The CD-ROM
contains specifications, stan-
dards and protocols of com-
mercially available bus and
network systems. For develo-
pers, there are datasheets of
specific components and various items with
application data. End-users and hobbyists will
find ready-made applications that can be used
immediately. £12.95 (USS 22.90)

ECD Edition 3

Eieklohs Components Data-
base gives you easy access
to design data for over 5.000
ICs T more than 35.000 transis-
tors. FETs, thyristors and
tnacs, just under 25.000 dio-
des and 1,800 opto couplers.

All databank applications are
fully interactive, allowing the
user to add. edit and com-
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Brentford TWO 9HH Fax +44 208 261 4447

United Kingdom lifiail: saJes@eJektor-efectronjcs,co,!j

More information on www.elektor-electronics.oo.uk

Modern High-end Valve Amplifiers

Valve amplifiers are regarded by many to be the
ne plus ultra when it comes to processing audio
signals. The combination of classical technology
and modern components has resulted in a
revival of the valve amplifier. The use of toroidal-
core output transformers, developed by the
author over the past 15 years, has contributed
to this revival. This book explains the whys and
wherefores of toroidal output transformers at
various technical levels and offers innovative
solutions for achieving perfect audio quality.

VAWJtAma J-.3

ISBN 978-0-905705-63-7
26-5 Pages

£25.95 (USS52.00)

Visual Basic

for Electronics Engineering Applications

This book is targeted towards those people that
want to control existing or home made hardware
from their computer. After familiarizing yourself
with Visual Basic, its development environment
and the toolset it offers are discussed in detail.
Each topic is accompanied by clear, ready to
run code, and where necessary, schematics are
provided that will gel your projects up to speed
In no time.

Me

lor

Itactiatucs
Engineering
M

ISBN 978- 0 - 90 57 05 -6S -2
476 Pages

E27.5D (USS 51.50)

BESTSELLING BOOKS

Top-5

Visual Basic

for Electronics Engineering Applications

ISBN 978-0-905705-68-2 £27.50 (USS 51.50)

( 5 ) Microcontroller Basics

ISBN 978-0-905705-67-5 £18.70 (USS 33.70)

( 5 ) Modern High-end Valve Amplifiers

ISBN 978-0-905705-63-7 £25.95 (USS 52.00)

(S) PC-interfaces under Windows

ISBN 978-0-905705-65-1 £25.95 (USS 52.00)

(a) Designing Audio Circuits

ISBN 978-0-905705-50-7 £20.75 (USS 42.00)

More bestsellers on www.elektor-electronics.co.uk

Four components
packaged together in a
single box. Thanks to an
exclusive and one-off
arrangement with
Microchip UK f the
Explorer-16 Value Pack
is both unique (you won’t
find it anywhere else in
this configuration) as well as much cheaper than the
individual comoonents.

'

Explorer-16 Value Pack

(January //February 2007)

Explorer- 16 Demo Board

Including P1C24F and dsPIC33F PI Ms, CD-ROM, cable
PIC Kit 2 Starter Kit

Including Low Pin Count Demo Board for 8-, 14*, and
20-pin PICmicros.

Audio PICtail Pius daughterboard

MPLAB C30 Discount Voucher

060200-91

£122.90/ $232.50

USB Stick with ARM
and RS232

(November 2006)

Assembled and tested board

050003-91

£ 79.90/ $149.95

GameBoy

ElectroCardioGraph

(October 2006)

RGB, ready built and tested

050280-91

£ 55.20/$ 103.95

MORE READY-BUILT PROJECTS E $

GlariTy 300-W Class-T Amplifier

03-3217-91 A rnp bct'd - SMDs pre-Eited, fb# Ll «S- L2 34.50 55.70

Electrosmog Tester

0SO^91 PCB, ready fault and tested 50.00 94.25

05C00-S-71 Matdmg enckisure 10,55 19.30

Flash Microcontroller Starter Kit

010203-91 PCS intit, software; csfe. & ret^d eticfes 69,00 112.59

Gemehoy Digital Sampling Oscilloscope (GBDSO)

990062- Ftev ^ 5«nr J .ad teatl, t ha PC soft am ar-rs r - 'a- ad arT : =3 1 03 |Q 1 S3 . 00

LPC210X ARMee Development System

540444-91 Processor bosrct ready-mada and tested 25,50 43.05

Micro Webserver with MSC1210 Board

G3C069-91 Microprocessor EostJ. ready -assembled 75.90 142*05

C4400S-91 \€V:.^r. Brten&rai Beam, maay^assemi- aa: 44.50 B3.95

04402 6-S2 CccniMned (O3O06D-31 1044026-91 imialsd articles) 117.50 220.55

No, 362 FEBRUARY 2007

.,.3* 2, 1 Takeoff!

0=0233-1 TfsrtsnwUBf PCS. bam
050230-2 Ftec-v:-: FCE tara

MP3 Preamp

G5G237-* PCS. Cam

A Telling Way of Telling the Time

0503111 PC®, bare
C-3Q3 11-3* C PL L p fogrammed

FPGA Course (9)

063325-9- n CD-FCW 10 software r-zK ec-_'C 6 coda

Explorer-16 Value Pack

060280*91 Fc-jr :z~&z'i*7:= ps:- 55ad r : 3 e -g’= b = ■

No. 361 JANUARY 2007

Sputnik Time Machine

050018-1 P€e

05S) 16-11 CC^nOV scTtware " : . 0 : „ 6 zzi*:

G5O01 6-41 AT E I- C2G51 , prog rammed

\

AViV..thapcfash3p.ccm

WWW .tfr 0CwShGp.CC"

■:.%v:.:ihepeb5fep.cPrTi

y. v/.v thepebshep. com
25.50 £5 95

520 9.75

122.90 C32.50

i , .viw.thfipdKfao^JXitn

5 28 ' 9.75
3,40 £,45

Very Simple Clock

060350-1 PCB

056350-11 CD-ROM, preyed sc h .vara (<nd, source coda}
06G35G-4I RClcf£2B-20 t progrerrared

FPGA Course (6)

060325-9-1 SefrAare ■ ” = :_x=:::=

Shortwave Capture

030417-1 PCB. bare (receiver face."

030417-2 PCB, tars (centre* & cEspsay boards)
030417-41 ATBDSSSlS-fiFC, programmed

No. 359 NOVEMBER 2006

vyva v. ttefxcbsftop . Mm
^20 9.75

5.50 10 35

52Q 3.75

vtVM.thapcl^og.cpm

ViViVNth0pCfc3hCO.COfTi

11.40 21.45

USS Stick with ARM and RS232

06O0D6-1 bar*

060006*41 AT91SA.M7SS4. programmed
060096-91 -Vissmfcisd ;. listed beard
060QDE-S1 CB-R0V s fftrect *c1tv-a.-5

No. 358 OCTOBER 2006

1100 20.75
27 .£0 51.95
79.90 149.95
5,20 9.75

PIC In-Circuit Debugger/Programmer

GS8346-1 PCB

050348-41 FiClcrfiTT, r^nammed
050348-7! K; 1. -c -IB centre ar 3 "Z'ti

GBECG - Gameboy ElectroCardioGraph

050250-91 PCS, reed) cj ; :t tislea

ECG using a Sound Card

045479-1 PCB-

04 5179-61 CD-ROM, a I meet software

No. 357 SEPTEMBER 2006

5.29 9,75

17.03 33.75

34.50 64.95

55.29 1G3.S5

520 9.75

5.29 9 7 5

Efektor RFID Reader

050132-91 PCB ready a&;em; ed L tested. -Ctti UES :=i 5

41 .50

7" 25

039451 -72. S:£“ i b a: -. -4 LC i.

7^5

13.65

G8Q 1 32-7 1 1 ,!it “ - ar cic-su

3.90

16.85

€80132-51 C-D-PQV a. r^-t; e'e

5-20

975

Experimental RFID Reader

06022 1 - it G > e pre a:: ± oftw = '£■

5.20

9,75

G6Q22 1-41 A“me-aai 6 p J . g ■'£- ~ ed

8.90

16.65

No. 355 JUNE 2006

FM Stereo Test Transmitter

G5026&-1 PCS

Network Cable Analyser

050302-1 PCS

050302-1 1 D is k . PIC source- code
05D3Q2-41 FiCleF574-20:P

n j
ej

5J

■6;

DiSEqC Monitor
040^-1! Dfek.PICsaxee4 frexcodb
040338-41 PlCl6F62S^-2aHprtgraiTCned

USB/DMX512 Converter

060012-11 Daks: project software
060012*41 P:C!eC 7A5. p:>gra.rr«-nt=d

No. 356 JULY/AUGUST 2006

RC Servo Tester/Exerciser

040 172*11 D pro -eel sonrisre
040172*41 PJC16FS4/A. pra-yammed
040172-71 Kit* ind. PCS. contrttfter, aS parts

LED Thermometer

0301 ?KM 1 D h* preset iofhvsrg
O30I9C-41 PlClE^73-2aSR prograir-^ea

Toothbrush Timer
030 1 46- i 1 Os >: D' C c-c 1 A 3T5

050146-4T AmJS23l3-10PC. pfog^rered

Easy Home Control

Q50&33+11 Disk, project software
050233-4 1 PrC 1 c F84 prog ra rr ~ 5*3

Universal LCD Module

050259-1 1 D $v. prc- ; -&c 1 ktlv.'S^

B5Q25SH 1 AT ? r .-32 3 ■ 3 , prajrarr m ~i

1-Wire Thermometer with LCD

060090- 1 1 D: <: pro t sc P.va.^

:e::c:-4- = i6F8aa-:.4-;= -

GBPLC -Gameboy PLC

050190*1*2 PCSs, bare, GBPLC MocMG & Programming Interface

050190-51 Pfogrammed PAL EEPRQM and Fish 1C

050190-91 Readytxtft and tested GBPLC Mcsiie and ftotyanming interface

GBPLC - I2C I/O Box

pecq^-l PCfl,fcaro

OKfi'tfS-St R v-i'j , - L _ =.--3 tee I id tea.' d

Binary Clock

02039CM1 5 5 - pn^-^cl seftwa.^

Q3B9CH41 RC?C54*C-4^progfan¥ntd

5L®

9.75

5.50

10.35

S2d

9.75

6 JO

12.95

529

9.75

T0.S3

19.40

22.70

42J5

5.20

9.75

15.50

31 .00

5ZQ

9.75

6.90

12.95

5.20

9.75

10.30

19.40

5,20

9,75

690

12.95

□JED

9.75

10.30

19.40

11.70

22.00

ms

20.75

B4.95

159,95

17,90

33.75

£4.95

159.95

5.20

9.75

8.05

15.10

No. 354 MAY

Onboard OBD-2 Analyser

050176-72 m ct pads, wicl 05017&-1 , 050176-2. 050176*42. afl te-mpocaftfs.

exd. LC0 and Ca$E 24 63 46.70

050176-73 LCD, 4x20 character Y«itft te£> ighi 25.60 54.50

050176-74 Case Scp‘s L" 160 yw.Lh Perspe* ccvst ard moaning ps-s 15 60 29.00

Q5Q176r42 ATmegalS, programmed 10_30 19.45

050092-71 OBD-2 AnaJySfcr Kit of parts wStout c=b ■> 52.50 96.95

050092-72 OSD-2 Anfltjrav; DBS to OSD adapter estife 27.55 51.95

Mini ATMega Board

G591 75-1 FCB. :nc» jdes adapter FCB 05€ 1 76*2 5.95 16.85

No. 353 APRIL 2006

>nline at

lectronics.co.uk

Due to practical constraint, final illustrations and specifications
m^y differ fram pubTisliad designs, Prices subject to change.
See Y/\w^etektQf-^ecUonioscQ. uk for yp to date informal ion.

Elektor RFID Reader

{September 2006)

Ready-buili and tested PCB with USB port for connection
to the PC. Including USB cable; not including display and
enclosure.

Elektor Electronics (Publishing)

Regus Brentford
1000 Great West Road
Brentford TW8 9HH
United Kingdom
Tel.: +44 (0) 208 261 4509
Fax: +44 (0) 208 261 4447

Email; sales@elektor-electronics.co.uk

Kits & Modules

GameBoy Programmable Logic Controller

(July/August 2006)

GBPLC Module

Read '/-assembled and tested
GBPLC Module and
Programming Interface
050190-91

£ 84 . 95 /$ 159.95

LC display

030451-72

£ 7 . 25 /$ 13.65

CD-ROM (all project software)

060132-81

£ 5.20 / $ 9.75

Combined package

GBPLC Module and I/O Extension

£ 149.80 / $ 279.00

- Read and write 13.56 MHz RFID cards

- M1FARE and ISO 14443-A compatible

- Programmable

060132-91

£ 41 . 50 / $ 77.95

Matching enclosure

060132-71

£ 8 . 90 / $ 16.85

GBPLC PC I/O Box

Ready assembled and
tested board
060098-91

£ 84 . 95 /$ 159.95

Simple rech arable A Cell Analyser

G5G334-! PC 9. bare

050334-1 1 Dg*_ PC Software

Universal SRI Box

050193-41 A739C2051 -24PC Frcg^mmed

4,80

5.18

725

904

9.75

13-65

[ No. 352 MARCH 2006

Application Board for RSC/13

D=0 179-92 P -j e g j '-assfrn c led bc-ara

48:27

90.94

OSD 173-1 PC 6

13,77

25.94

03945 1 -72 LCD wnfi bad-; 1-oht

7.25

13.65

D30451-73 Ptfy-lED ctepia.

25.50

43.05

Products for older projects (if available) may be found on
our website www.elektor-electronicsxo.uk

home construction = fun and added value

PREVIEW

Function Generators on Test

hi sErious faultfinding in electronic circuits you not only need a multimeter and an cm i Hostage, but also a generator to supply
a suitable input signal. A function generator is the perfect instrument offering selectable waveshape, amplitude and frequency.
We pul 18 commercial function generators with a sub £450 price tag through their paces. Without giving away our conclusions
just yet p vie were not disappointed by their price/performance railo.

New micros on the block: Freescale MC9S08

In this article we introduce you to freescale 1 ; MC9S0B range of microcontrollers. Relatively new to the market and not covered
yet in Eluktor, those devices fit perfectly m the 'all- 'microcontrollers' theme we Ve set ourselves for the March 2007 issue. The
article goes to show I hat these low-cost micros ore remarkably easy to use 1 hanks to ingenuous software and hardware tools
colled Code Warrior and Spyder respectively. The article will culminate in the April 2007 issue wilh the description of o -i -direc-
tion accelerotTon/decelerolian indicator.

Mobile Phone LCD Recycling

We're sure many of you have a discarded mobile phone somewhere in o
drawer. You If like to hear that mony ports from these mobiles con be reused
for electronics projeds, the LC display being ihe most interesting item, in this
article we show how the LCD salvaged from on Alcatel GTE db mobile can be
driven from □ small ATMegal 6 board or a PC R5232 port.

Also...

Explorer-1 fi (3);

Fairchild 30-Year Anniversary Project;
Wireless ATMega/GSB Iransceiver*;
Very Simple Oock*; Mini Project;
Hexadoku.

' f i= rtsrs! lid ofijfes [gUHdoJ be sttsaano"

It tke MtfiEry 100? isscs m. placed.

RESERVE YOUR COPY MOW!

OK mallard *uhscrifci» hill rzizm fh=- mcgutlne bt* ten 24 mid 27 February 2007.

Tb March 2007 iswe gc-ss on sole on Wafaes-iny 23 February 2007 (UK dstrifaultin c-:!y)
Aitkls tides end iwgpfc tan tents subject to thongs, pi to chHfewww.dekior ^&rironja.{o.uk

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Components for projects appearing in Elektor Electronics are usually a * 1 . affable from certain advertisers in this magazine, if difficulties in the supply
of components are envisaged, a source will normally be advised in the article. Note, however, that the SDurce(s) given es rerej not exclusive,

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components, and so on. described m our books and magazines, Elektor Electronics i Publishing does not accept responsibility or liability for failing
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January' 2007

olIrMor sId£|id)i^cs

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2/2007 ■ clfklor tlenrc-n: :s

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