Newest circuit diagrams

Computer Microphone

This circuit was submitted by Lazar Pancic from Yugoslavia. The sound card for a PC generally has a microphone input, speaker output and sometimes line inputs and outputs. The mic input is designed for dynamic microphones only in impedance range of 200 to 600 ohms.

Brightness Control for small Lamps

Switch-mode driven 1.5V bulbs. Portable unit - 3V battery supply

FM Stereo Transmitter

This is a small stereo FM transmitter. Output can be tuned from 88to 108Mhz and the transmitter can be battery powered or be used with the low voltage power supply on this page.

Motorcycle Alarm No. 3

This circuit features an intermittent siren output and automatic reset. It can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition. By adding external relays you can immobilize the bike, flash the lights etc.

Amp with Tone Controls & Soft Switching

Built around an LM380, this amplifier includes tone controls and electronic "soft switching". The soft switching circuitry ensures power is built up gradually eliminating the dc thump.

24 Hour Timer

These two circuits are multi-range timers offering periods of up to 24 hours and beyond. Both are essentially the same. The main difference is that when the time runs out, Version 1 energizes the relay and Version 2 de-energizes it. The first uses less power while the timer is running; and the second uses less power after the timer stops. Pick the one that best suits your application.

Touch Counter

The counter is advanced by one touching a wire of the LED, Suitable for many applications

Magic Wand Conjuring Trick

The simple conjuring trick in Figure 1 is intended to provide some enjoyment for the beginner in electronics or conjuring, and should take only an hour or two to build.

Portable FM Transmitter

A portable FM transmitter that can be used to replace a FM microphone.

The Output Adjustable Flyback Converter

A high voltage step-up DC power supply using adjustable flyback conversion.