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.
An OR gate can be implemented with an LM3900 transconductance operational amplifier. The circuit is...
This traditional relay configuration, found in old documentation, is intended for 2A relays for...
This simple radio circuit was obtained in a Japanese publication in 1967. The circuit uses...