Found in American documentation from the 1980s, this circuit prolongs the ringing of a doorbell or chime powered by a 6 V continuous voltage. The transistor can be a BD136.
This circuit was found in a 1970 IEEE publication. The circuit functions as a voltage controlled...
Found in a documentation from the 90s, this circuit limits and amplifies a voice signal in the 800...
This gas sensor circuit was found in July 1976 Radio Electronics magazine. The TGS sensor was a...