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SEPTEMBER 1 989
FEATURES
6 Electronics For Everyone
Pt.4: potentiometers & trimpots
by Leo Simpson
YOU WON'T BELIEVE how
good stereo AM radio can sound
until you build this nifty little
receiver. It's based on the
MC13024 IC which is virtually a
complete AM stereo radio on a
single chip. See page 20.
16 Scopeman Video Microscope by Leo Simpson
The easy way to view small objects
88 The Technology Letters by Richard Kopf
Fun & games in the security industry
102 The Evolution of Electric Railways by Bryan Maher
Pt.23: Swiss tunnels & racks
PROJECTS TO BUILD
20 2-Chip Portable AM Stereo Radio
by Steve Payor
Hifi in a small package
27 Alarm-Triggered Telephone Dialler by Greg Swain
Add it to your home burglar alarm system
THIS AUTOMATIC
TELEPHONE dialler can be
added to any home burglar
alarm system and will call a
pre-determined number if the
alarm is triggered. Construction
starts on page 48.
52 High Or Low Level Fluid Detector by Peter Gray
Low cost circuit has many applications
60 Studio Series 20-Band Stereo Equaliser by Bob Flynn
Construction plus troubleshooting details
80 Null Your Amplifier's DC Output To Zero
by
J. Clarke
Simple add-on circuit uses a single IC
SPECIAL COLUMNS
12 Vintage Radio by John Hill
Valve portables -
hard on batteries
40 Serviceman's Log by the TV serviceman
It's a long way to trip a "rarery"
72 Amateur Radio by Garry Craft
VCR FAULTS CAN be tricky
but the serviceman eventually
got it all back together again.
His battle starts on page 40.
Simple DTMF encoder for custom control circuits
75 Computer Bits by
Jennifer Bonnitcha
A guide to hard disc drives
93 The Way I See It by Neville Williams
HDTV: lots of problems at the transmission end
DEPARTMENTS
2 Publisher's Letter
3 Mailbag
11 Subscription Page
35 Back Issues
58 Circuit Notebook
96 Product Showcase
108 Ask Silicon Chip
110 Market Centre
111 Notes & Errata
YOU CAN USE this simple
circuit for detecting high or low
fluid levels or for monitoring
soil conductivity in greenhouses.
Turn to page 52.
SEPTEMBER1989
1