Found in Popular Electronics from the 90s, this circuit turns off an appliance at the end of the programmed time. The 12 V relay must have contacts according to the controlled current.
This circuit is from a 1979 documentation. The critical component is the CA3130 operational...
This circuit can be used with 3 receivers and is intended for low frequencies (medium wave range). We...
This circuit shows how to control a TTL logic gate with a phototransistor. The phototransistor supports an...