Emergency
Stand-By Light - A home emergency light that uses a 12V lead acid
battery to power a small inverter, sufficient to light a 24W maximum fluorescent-type
energy saver lamp. A typical 60Ah battery offers 24 hours of illumination,
or use e.g. an 11Ah SLA to give about 8 hours with an 11W lamp.
This project
generates mains-level voltages from a 12V battery.
For experienced constructors only.
Not for use with tungsten filament bulbs or any other electrical appliance.
MIDI
Health Check - check out your MIDI home
studio setup with this transmitter-receiver pair. This system will transmit
and receive single messages to demonstrate the presence
or absence of meaningful code signals. Each unit has a PIC-powered circuit
and LCD module to display a troubleshooting channel message.
PIC
Mixer for RC Planes - This unit is a flight command mixer for delta
and V-tail radio controlled model planes. High resolution servo control
design. PIC 16F84 powered. Has optional buzzer/ sounder function to help
you locate your landed craft in undergrowth etc.
PLEASE
TAKE NOTE: A revised version of the software was placed on our Downloads
area to replace a minor bug in the battery level detection routine.
Bat Band
Converter - A fascinating and ingenious way of listening to the sounds
produced by bats. This Beat Frequency Oscillator (BFO) design detects
the ultrasonic frequencies of bat squeaks using an ultrasonic or piezo
transducer, and shifts them to human-audible levels, enabling you to listen
in on a crystal earpiece. Built-in frequency and sensitivity controls,
completely portable and self contained.
PLEASE
TAKE NOTE (May 2004) Some constructors reported a problem with acoustic
feedback, which varies according to the receiver and the earpiece used.
The May 2004 issue (p.331) gives details of a circuit modification if
required: remove the link between pins 8 and 12 and substitute it with
two 1nF capacitors soldered in series. Pin 12 is taken to 0V through a
10k resistor, and the junction between the two 1nF capacitors is also
grounded through a 10k resistor. The May 2004 issue has more details on
page 331.
Also in this issue:
- Teach-In 2004 Part 5 - Logic Gates as Switches. Continuing our specially-written 10 part beginners' series introducing electronics systems and components.
- Ingenuity Unlimited - three pages of readers' own circuits!
- Circuit Surgery explains diacs and triacs, and how to parallel voltage regulators properly.
- Techno Talk - read how "disruptive technologies" are good news for some, and bad for others.
- Net Work - the Internet page: how to back up all your Outlook Express files safely.
- Practically Speaking - we show you how to mount components properly on circuit boards.
All this and more in the No. 1 hobby electronics magazine!