This circuit was found in a 1967 EEE. The components are from that time, but the circuit can be implemented with modern equivalent components.
This circuit was found in an American audio documentation from 1968. The configuration can be...
This circuit was found in 1980s American documentation. The transducer is a piezoelectric capsule and the...
This circuit is from an English magazine from 1976. By replacing the transistor for a BC548, the...