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 the 1976 Siemens transistors manual, this circuit works with AM or FM IF signals. In the...
Three 4011 NAND gates and two more components - a resistor and a capacitor make this oscillator very...
This photoelectric circuit was found in a 70’s Ferranti's documentation. The circuit uses an...