This 50 Hz rejector or notch filter was found in a 1975 documentation. Other frequencies can be obtained by changing components. The filter uses a Wien network and must use a symmetrical power supply.
This 600-ohm line driver was found in a 1980s documentation. The integrated circuit used is not...
We found this circuit in a 1977 Radio Shack manual. The light bands are given by the operating gain...
This transmitter uses a 741 operational amplifier in modulation. The microphone can be any type...