Suitable for clandestine listening and in SMD assembly, this circuit was found in the Radio Eletronics magazine of August 1988. The listening is in headphones and the amplifier is electret.
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...