Found in a 90s Popular Electronics, this circuit triggers a load from the audio signal applied to its input. The controlled load depends on the MOSFET.
It can be obtained from Mouser Electronics, sensors (receivers) transmitters and benders for...
Suggested by General Electric in a 1965 documentation, this circuit can use the TIC106 as an SCR....
The circuit shown is from the 1994 Linear Applications Handbook from National Semiconductor. The...