Found in 1968 Mullard documentation, this circuit uses period components. The transistors are matched pairs and the sensor is an Indian photocell of the time.
The sensor for this alarm is an LDR and it consists of an oscillator that goes into action when...
We found this amplifier circuit for inductive audio pickups in a documentation from the 70s. The...
This circuit is from an American documentation from 1976. The FET can be the BF245 or MPF102 and...