This very low frequency amplifier has a gain of 1,000 and was found in a 1967 documentation. The circuit is suitable for detecting explosions, distant echoes and seismic vibrations.
This circuit causes a bicolor LED or two LEDs of different colors to alternately flash at a...
Found in a publication from the 60's, this circuit uses the CK722, germanium transistor of the...
This circuit produces a sound when someone touches the handle that is used as a sensor. The...