This circuit was originally suggested in a 1968 publication to generate a white mark (frame) on a film at regular intervals to serve as a time reference.
Of course, other frequencies can be generated by changing the components. The circuit generates a...
This circuit was found in a 1974 publication. It provides a tone indication of the temperature sensed by...
This spy transmitter can be plugged directly into a power outlet. The power comes from a regulated...