Newest circuit diagrams

Doorbell Warning Switch

This circuit will light a lamp at a remote location when the doorbell switch is pressed. This circuit should only be used with the solenoid type doorbells, the electronic type that play tunes will not work here.

Square Wave Oscillator

A very basic square wave generator using a CMOS 4011 NAND gate.

5 to 30 Minute Timer

A switched timer for intervals of 5 to 30 minutes incremented in 5 minute steps.

Simpler Cmos Single Zone Alarm

This is a simple single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays and a timed Bell/Siren Cut-Off. It's designed to be used with the usual types of normally-closed input devices such as - magnetic reed contacts - micro switches - foil tape - and PIRs. But it can be Easily Modified to accept normally-open triggering devices - such as pressure mats.

Digital Remote Thermometer

Remote sensor sends data via mains supply Temperature range: 00.0 to 99.9 °C

LED or Lamp Flasher

Minimum parts counting - Improved version. 3V battery operation

Audio VU Meter

This circuit uses two quad op-amps to form an eight LED audio level meter. The op-amp used in this particular circuit is the LM324. It is a popular IC and should be available from many parts stores.

FM Transmitter Circuit

An low power FM Transmitter using an op-amp as the audio preamp and a single transistor as the RF amplifier.

Solar Battery Charger

A solar battery charger that uses a shunt regulator to prevent overcharging. Circuit uses a 12V solar battery, but can be adapted for other voltages.

TV Transmitter

This is an Analogue TV Transmitter. Sound modulation is type FM with a 5.5MHz carrier and video transmission is PAL. Frequency is adjustable via C5 and tunes 54 to 216Mhz with components shown. This is suitable for countries using TV systems B and G.