Elektor_2008-06.pdf

www.elektor.com JUNE 2008 AUS$ 12.90 - NZ$ 15.50 - SAR 84.95 - US$ 9.95 £ 3.90

electronics worldwide

SAPS-400

£ 2·00 RLC Meter

128 thermometers on a string

satisfactory results

nine soundcards

R26

on the rack

SMPSU for audio amps

can’t beat that price

Thermo-Snake

More than audio

Looking at this month’s magazi-

ne cover might suggest an over-

abundance of audio projects.

The balance is mote delicate

however, although it can be

argued that a fair number of

articles are related in some way

to audio.

The pages on the SAPS-400

describe a switch-mode power

supply unit (SMPSU) specially

designed for audio power am-

pliiers. This compact light-

weight unit can supply a hefty

400 watts continuously. The

main symmetrical output voltage

is adjustable across a wide

range and a separate ±15-V

auxiliary supply is incorporated

for powering a preampliier or

similar. SAPS-400 at last ena-

bles high-power, high-end audio

amps to be built where the

enclosure is not 75% illed with

bulky transformers and reservoir

electrolytics.

SMPSUs are now used in lots

of consumer and industrial

equipment because of their

small size and high eficiency.

Still, many designers hate them

for their design complexity and

non-standard parts. Typically,

the solution in these cases is to

use a drop-in supply. Our theo-

retical backgrounder on SMPSU

design on page 40 goes to

show that things might be less

complex than you think.

Our bench test of nine sound-

cards is not about sound

quality in the irst place. Lots

of electronics enthusiasts use

the soundcard in their PC to do

low-frequency measurements

and for that it’s essential to have

a linear amplitude response

and a known-good frequency

characteristic. That’s why we

did extensive measurements on

the technical specs for these

soundcards.

A handy application of the

soundcard is described in the

article ‘2-pound RLC Meter’. In

it we show how an exquisite

RLC meter can be built using no

more than your PC, the sound-

card, three components and

a little Java program — very

useful.

Happy reading!

score: 7.5

A comparative test of nine sound cards

The quality of A/D and D/A converters makes it quite tempting to use a sound card

for audio equipment measurements, especially as it its quite nicely in the Windows

environment. However, it takes more than good converters to make a good

26 sAPs-400

With the SAPS-400 we offer a powerful, adjustable symmetrical supply that’s ideal

for lightweight audio power ampliiers and happily sits in less than a quarter of the

space taken by a comparable supply of conventional design.

Jan Buiting

Editor

CONTENTS

Volume 34

June 2008

no. 378

projects

26 SAPS-400

SMPSU for audio ampliiers

34 Proiler Update

58 Thermo-Snake

64 2-Pound RLC Meter

70 Invisible Commands

74 LED Tester

A comparative test of nine sound cards

technology

instrument, as we all know. Our test shows how well a number of sound

cards score with real signals.

40 Cool Power

48 USB-to-TTL Serial Cable

50 Other uses for EIR

53 Elektor/Intel ‘unplugged’:

results revealed

54 Air, Power,

Sound and Heat

63 Mains Adapters

58 Thermo-snake

This low-cost project allows you

to connect from 1 up to 128

digital thermometers like

the Dallas DS18B20

directly on a single

two-wire cable. All temperature

values are recorded on your PC through a USB port without memory space

limitation. Using the software manager developed for the project you can

monitor the temperature in real time and set an alarm threshold value for

each individual thermometer.

info & market

6 Colophon

8 Mailbox

10 News & New Products

18 Score: 7.5

A comparative test of nine

sound cards

69 Electrical Safety page

80 Elektor SHOP

84 Sneak Preview

64 2-Pound rLc Meter

infotainment

Is it possible to make an RLC meter for less than two pounds? In this article

the authors answer this question with a resounding ‘yes’ in the form of a

simple and compact circuit that will enable you to make RLC measurements

rapidly, accurately, and, above all, cheaply.

76 Hexadoku

77 Retronics

Neuwirth FUP1D

PMR test unit (1973)

elektor electronics worldwide

elektor international media

Elektor International Media provides a multimedia and interactive platform for everyone interested in electronics.

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Analogue and digital; practical and theoretical; software and hardware.

E n g l i s h

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D u tc h

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Por tugal

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Volume 34, Number 378, June 2008

ISSN 1757-0875

Elektor is also published in French, Spanish, German and Dutch. Together with franchised

editions the magazine is on circulation in more than 50 countries.

Editorial secretariat: Hedwig Hennekens (secretariaat@elektor.nl)

Elektor Electronics aims at inspiring people to master electronics at any personal

level by presenting construction projects and spotting developments in electronics

and information technology.

Graphic design / DTP: Giel Dols, Mart Schroijen

International Editor:

Wisse Hettinga (w.hettinga@elektor.nl)

Managing Director / Publisher: Paul Snakkers

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elektor - 6/2008

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6/2008 - elektor

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