Rajkumar Sharma over at Electronics Lab writes:
This timer project can be used to switch ON/OFF any device after a set time, this circuit can be used in lots of application like switched ON/OFF Radio, TV, Fan, Pump, kitchen timer, the circuit describe here its unique in its own.
Project has been designed around two CMOS IC CD4001 and CD4020. Two gates of CD4001 make the oscillator and rest has been configured as flip-flop, BC547 transistor is to drive the Relay. Circuit is pretty simple, has jumpers to set the required time duration, Preset is to set the 1Hz oscillator. SW1 is to start the timer, SW2 Power on/off project. Relay output switch contacts can handle 230V AC @ 5Amps
Perhaps better described as a toy with CMOS chips. A kitchen timer with durations of 2, 4, 8, 16, 32, 64 or 128 minutes? *cough* *cough*