This oscillator that generates signals below the audible range (sub audio or infrasound) was found in a 1965 documentation. Transistors are for general use.
This circuit was found in the Electronics Experimenter Handbook from 1991. The sensor is a diode...
This circuit can be used on audio, video, or data links to receive modulated infrared signals. The gain is...
With this circuit it is possible to obtain a voltage modulated in amplitude with a maximum current of...