This circuit is from an old American documentation using as indicators for the flip-flops neon lamps. This way, the circuit has two supply voltages.
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...