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 circuit was found in the October 1989 issue of Radio Electronics magazine. It drives an...
This interesting configuration was found in a 1965s Electronic Design. It makes use of components of...
This interesting bandpass filter using an operational amplifier 741 has its cutoff frequency...