Using a common crystal diode and a 741, this circuit can be used to detect microwaves. The circuit is from old documentation and the switch selects the gains.
This oscillator circuit for sinusoidal audio signals with operational 741 requires a symmetrical power...
Found in a 1974 Radio Shack documentation. This circuit must have a connection to the ground of...
This sensitive circuit detects the live pole of a power grid or outlet. The circuit makes use of a high...