Silicon Chip – July 2019

siliconchip.com.ausiliconchip.com.au Australia’s electronics magazine July 2019 1

Vol.32, No.7; July 2019

Contents

http://www.siliconchip.com.au

SILICON

CHIP

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Features & Reviews

14 Radiation and Electronics don’t make good bedmates!

Natural and artificial radiation sources can have adverse effects in aircraft,

spacecraft and even life support systems – by Dr David Maddison

32 Modern PCBs – how they’re made

Modern production techniques can mean it’s very economic to have even a small

number made for you – as long as you can spare two weeks – by Tim Blythman

61 El Cheapo Modules: AD584 Precision Voltage References

Three variations on a theme, all using the AD584 IC from Analog Devices. Obtain

highly accurate 2.5V, 5V, 7.5V or 10V references – by Jim Rowe

Constructional Projects

24 Dual Battery Isolator for 4WD, RVs, Caravans, etc

If you run a second 12V battery in your vehicle, van, etc you know you cannot

simply connect them in parallel. This cheap, solid-state isolator will allow the

second battery to charge while the engine is running – by Bruce Boardman

44 Speech Synthesis using a Raspberry Pi Zero

With a low-cost Raspberry Pi and our simple hardware and software, you can make

your projects talk – in just about any language. If you want, they can even play music!

• by Tim Blythman

74 Building the RF Signal Generator (Part 2)

If you’re into HF or VHF radio, you really need an RF SigGen. This one is low cost

and quite simple to build. And this month, we get into doing just that: building it!

• by Andrew Woodfield

86 DSP Active Crossover and 8-channel Parametric Equaliser

The third (and final) part of this incredibly versatile project shows you how it all

goes together, testing/troubleshooting and finally connect it to your system. Plus

we show and explain all 32 control screens – by Phil Prosser and Nicholas Vinen

Your Favourite Columns

68 Serviceman’s Log

Repairs for a “key” client – by Dave Thompson

94 Vintage Radio

The National Panasonic AKQ Walkabout portable – by Ian Batty

99 Circuit Notebook

(1) Guitar practice preamplifier based on inverters

(2) 74LS-series and 74HC-series logic tester

(3) Electrocardiogram based on Micromite Plus Explore 100

(4) Horse racing game using an alphanumeric LCD

Everything Else!

With a usable

range up to

150MHz, this

RF Signal Gen-

erator is a great

addition to any

workbench –

Page 74

Got a second

or “house”

battery in your

van or 4WD?

Here’s how to

charge it safely!

• Page 24

2 Editorial Viewpoint

4 Mailbag – Your Feedback

43 Product Showcase

104 SILICON CHIP ONLINE SHOP

106 Ask S^ ILICON CHIP

111 Market Centre

112 Advertising Index

Making

radiation-

proof devices

is the holy

grail – and

they’re

making some

real advances – Page 14

Built a project but

you’d like it to “talk”

or play music? It’s easy with this

simple hardware and software–

Page 44

You can still

make PCBs at

home but for

the price, speed

and service of commercial PCB

houses, it’s hardly worth the bother!

• Page 32

Finishing off the DSP Active

Crossover and 8-channel

Parametric Equaliser – Page 86