This sound relay or Vox was found in 70s RCA documentation. SCRs can be common types today and transistor a BC558. The circuit is for the 110V power grid.
This frequency-corrected 1 kHz circuit has a nearly perfect rectangular signal. The circuit is...
This signal injector uses a single integrated circuit as an oscillator, producing rectangular...
This high power transceiver provides a few watts of output thus enabling long distance...