This circuit was found I a 1965 Radio Schack documentation. The transistors are from that time, admitting equivalents. The transformer has 500 ohm primary and secondary depending on the speaker.
This circuit was obtained in an old American publication from 1978. It can be assembled with a...
Decade counters, such as the 4017, can be cascaded as sourcing signals with the frequency divided...
This circuit uses a dual-gate MOSFET, a rare component today. We found it in American...