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 is a commercial circuit from the year 1958. Transistors are germanium types and transformers...
This circuit, of a Popular Electronics of 1969 is destined to firing a gas LASER of the time. The...
The operational amplifier used in this project no longer exists, but the circuit can be adapted to...