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 crystal configuration can be made with triggers of any logic. The frequency is given by the...
This circuit was obtained from an 80s factory manual. The integrated circuits used are uncommon...
We found this circuit in an old American documentation. It is an electronic rheostat with a...