We found this circuit in an American 1980s documentation. The circuit uses a piezoelectric transducer unusual in our day. The transistor is general purpose type.
This amplifier for sound equipment was found in the Philips Databook of 1990. The circuit can be...
This amplifier circuit for listening was found in a book by Hugo Gernsback from 1960. The...
This circuit was found in a 1977 Radio Shack documentation. The circuit is TTL, which must be...