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 timer was found in a 1994 Electronics Now. The relay must be a sensitive type. If it has a...
Published in the September 1973 issue of Radio Electronics magazine, this diagram may be useful to...
This circuit with 4 diodes was found in the July 1984 Radio Electronics magazine. The voltage of...