This class B circuit was found in the 1960 Mullard transistor reference manual. Transformers are the critical components. The source is not symmetric.
We found this simple alarm circuit in a 1986 documentation. The circuit uses sensors of the NA...
This sound relay or Vox was found in 70s RCA documentation. SCRs can be common types today and...
Placed near a common receiver, this oscillator is intended to generate a beating signal to receive...