This circuit was found in a Popular Electronics from the 90's. The operating curve is given next to the diagram. The power transistor must have a heat sink.
This circuit is from the documentation of Radio Shack 1975. It can be mounted with 12 V relays,...
Using an optocoupler this circuit turns on the light in a bedroom for a set amount of time when...
This circuit is used for remote current monitoring. In the original version of the 80s a lamp is...