Elektor 10.2009.pdf

www.elektor.com October 2009 AUS$ 13.90 - NZ$ 16.90 - SAR 99.95 £ 4.65

electronics & microcontrollers

The Sound

10 noise cancelling headphones tested

for mountaineers, delta glider & UL pilots

Barometric Altimeter

✔

PSoC kit with RF module – Portable solar chargers – Noise is not cool!

LED touch panel for Arduino

Hearing treshold tester

R43

of Silence

E-LABS INSIDE:

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D E V E L O P M E N T T O O L J U S T T H E W A Y Y O U L I K E I T

Everything you’ve always wanted from a development tool

Experience the ease of creating your own electronic devices!

Thanks to many new features, you can start creating your own devices

immediately. EasyPIC6 supports 8-, 14-, 18-, 20-, 28- and 40- pin PIC

microcontrollers. The mikroICD (Hardware In-circuit Debugger) enables

very efficient step by step debugging. Examples in C , BASIC and Pascal

are provided with the board.

Hardware In-Circuit Debugger

for step by step debugging at

hardware level

High-Performance

USB 2.0 On-Board

Programmer

Port Expander provides easy

I/O expansion (2 additional

ports) using serial interface

On-Board

2x16 Serial LCD

Display

Full-featured and user-friendly

development board for PIC

microcontrollers

Keypad enables

easy and fast data

entry

mikroElektronika

Find your distributor:

http://www.mikroe.com/en/distributors/

SOFTWARE AND HARDWARE SOLUTIONS FOR THE EMBEDDED WORLD

www.mikroe.com

electronics & microcontrollers

Feedback is good!

At social gatherings the conversation

often comes round to what you do

for a living. Editor sounds a bit exotic

and the question then turns to what

skills are needed for the job.

Many years ago, a (very) senior

editor divulged that you should be

something of a craftsman.

The analogy is not a bad one: to

be successful you need a little bit of

talent, loads of practice and a touch

of artistic ﬂ air. I have to admit that our

magazine is not always a master-

piece but I never doubt the level of

commitment of our team. I always

look forward to the end of the month

when we sit down with some pride

(and relief) to thumb through the latest

edition hot off the press.

However the analogy breaks down

here — unlike the tailor, carpenter

or sculptor we never get to see the

customer’s face when they take

ownership — or in our case read the

magazine. Rarely do we get to know

if our choice of an article was a good

one, if the writing style is good or

indeed what the overall impression

was. It is a shame because we are

continually asking questions: How

many projects or articles on funda-

mentals should we run?

Do our soft/hardware descriptions

have enough depth? Are readers

interested in projects that don’t

include microcontrollers? Should

the articles have a common layout

or would it make a more attractive

product if each article has a different

layout?

Raise that question at an editorial

meeting and you are sure of a heated

argument. It is interesting to see which

work colleague takes which side in

the debate. At the end of the day of

course what we think is really not

important, the customer is king!

We really do value your feedback.

Whether you found something to be

really interesting or a total turn-off,

we don’t mind criticism — in fact

we encourage it! Maybe you would

prefer to see the magazine concen-

trate on different subject areas or you

dislike the direction the magazine

is taking. Whatever the case, let us

know, we look forward to your views

at editor@elektor.com, or by post.

14 Sound Sorcery

The science of acoustics holds many surprises: sound can be focused into

beams, noise can be cancelled out by more noise, and sound waves can

be made to appear from nothing as if by magic. This article explains

how the tricks are done.

20 Barometric Altimeter

Jan Buiting

Editor

In this project a piezoresistive transducer measures the atmospheric

pressure, enabling a PIC microcontroller to use the ISA model

(with temperature compensation) to display your current height

above sea level (ASL) on an LCD.

CONTENTS

Volume 35

October 2009

no. 394

projects

20 Barometric Altimeter

26 Touch LEDs for Arduino

36 Car Tilt Alarm

48 Hearing Threshold Tester

54 Pocket Preamp

58 Getting Started with Em-

bedded C (part 3, ﬁ nal)

66 Mini Preampliﬁ er

Very few people realise how much portable music

players like iPods and mp3 players can

affect our hearing.

The hearing threshold tester presented here

has been designed to check the state your ears are in.

technology

14 Sound Sorcery

E-labs inside

43 Portable Solar Chargers

44 “Noise is not cool”

46 Review:

PSoC kit with RF module

58 The Sound of Silence

info & market

6 Colophon

8 News & New Products

32 High End Audio Ampliﬁ er

Kits

58 The Sound of Silence

80 Elektor SHOP

84 Coming Attractions

In this article we take a look at

a number of noise cancelling headphones,

designed to reduce background noise

using anti-sound.

How do these devices perform,

and what’s the price tag?

infotainment

74 Hexadoku

76 Retronics:

Philbrick R2-W, the mother of all

op amps)

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