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 an old Radio Electronics, this circuit uses common components today. The resistors of the IC...
This circuit was published in an article in Electronics Now magazine in October 1995. The circuit...
This DC-DC converter was found in old RCA documentation. The circuit operates at 15 kHz. The...