Found in an Electronic Design from the 90s, this circuit measures the phase difference between two signals using an electronic multimeter. The circuit makes use of components of the time.
This sound relay or Vox was found in 70s RCA documentation. SCRs can be common types today and...
We have here a very interesting project found in a 1982 publication. By the operation of the...
This circuit was found in a European publication from the 1980s. The operational amplifier is not...