This frequency triple oscillator circuit was found in an American publication in 1967. The FET is current and more detailed information about the coils is not given.
This power supply was found in a RCA publication from the 1970s. The circuit uses transistors from that...
This circuit was found in a 90s Popular Electronics. It produces a muted tone similar to that...
This circuit was found in a 1980s documentation. The diode is general purpose. The circuit is...