Timer circuit diagrams

741 Astable Timer

An astable timing circuit made from the ubiquitous 741 op-amp.

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.

Courtesy Light

15 seconds delayed switch-off. A good idea for bedroom lamps

5 to 30 Minute Timer

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

Jogging Timer

3V Battery powered. Beeps after a fixed minutes delay

Timed Beeper

Beeps 7.5 seconds after a preset time Adjustable time settings: 15 s. 30 s. 1 min. 2 min. & others

Long delay Timer

This timer was designed mainly to switch off a portable radio after some time: in this way.

NE555 Monostable

Use of the ubiquitous 555 timer in monostable mode.

555 Pulse Generator

A 555 pulse generator circuit with a difference, the initial pulse is tailored by additional circuitry to match the duration of subsequent pulses

Asymmetric Timer

A timer circuit with independent mark and space periods.