This sound or voice relay was found in a Popular Electronics. It includes an amplification stage and can be used as a shield.
Based on Allegro's A6275, this circuit controls the brightness of various displays. The circuit is valid...
This small transmitter can act as a wireless microphone operating in the medium wave range,...
This is the circuit of an RCA Dimmer sold in 1967. With it it is possible to control a load up to...