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 circuit, when triggered, locks, and remains so until the source is switched off for a moment or...
With the values of the components indicated, this timer controls intervals from a few seconds to a...
This circuit with a few watts of power was found in the April 1995 issue of Electronics Now...