This very simple circuit uses a phototransistor and a very sensitive relay (reed type) being used over short distances with a lens system. The circuit is from a 1967 Japanese publication.
This circuit for controlling high power in the AC network was found in a Motorola documentation from 1968....
Found in American documentation from the 90's, this circuit consists of a solid state relay with...
This oscillator uses a small transistor amplifier or radio output transformer. We found it in a...