This long interval timer was found in the September 1976 issue of Radio Electronics magazine. The output can be used to control a relay. The circuit achieves timings of up to 14 hours.
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...