We found this circuit in the magazine Eletcronics Now of July 1994. The power supply is according to the relay and the transistor can be any general purpose one.
This old slide projector control circuit was found in an 80s Hands On. The circuit uses modern...
In the figure we have a circuit that uses unusual components, being indicated for low frequency...
The sensor of this circuit found in Popular Electronics can be formed by a piece of fabric between two...