This is the receiver for the previous transmitter. The microphone is of the high impedance ultrasonic type. The circuit activates a relay. The operational amplifier supports equivalent.
Found in a 1970 publication by General Electric, this circuit makes use of a mobile...
This circuit switches on an external load after a certain interval given by the capacitor. The...
Using common SCRs like the TIC106, this circuit is loaded with incandescent bulbs, but can be...