This circuit was found in the February 1990 issue of Radio Electronics magazine. The gain is given by the capacitors according to the table next to the diagram.
This full wave source uses germanium diodes, and its current is a few milliamps. We found it in an...
This circuit is from a 1968 documentation. It makes use of thermistors (NTC) to indicate...
This small transmitter has an RF amplifier stage with coupling made from the central socket of the...