Found in American documentation from the 1980s, this circuit makes use of components of the time, which are uncommon today. The circuit detects the approach using a sensor formed by metal plates.
This circuit is from an 80's Radio Electronics. It triggers a load powered by the power grid from...
This circuit trips, changing state, when the input voltage exceeds a value determined by R1 and...
Transistor Q1 can be a BC558 and Q2 a BC548. This circuit detects when a pulse is missing from a...