This circuit doubles the frequency of an audio signal, thus changing its timbre. The circuit was found in an Elektor from the 90s. The components are common today.
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...