Process timer (CB21865E)

We found this timer for times of a few minutes in a 1974 Ferranti transistor manual. The relay is 37 mA sensitive type.

Photo-Oscillator (CB217E)
The frequency of the signal produced by this oscillator depends on the amount of light falling...
1 kHz tuning fork (CB14363E)
The circuit presented is based on a mechanical tuning fork. The circuit is suggested by National...
RC Oscillator with 741 I (CB19111E)
This is a well-known RC oscillator configuration using a 741 operational amplifier. The circuit is from...