This circuit was found in a Radio Electronics from February 1966. The circuit operates with a common battery and the frequency is given by the resonant LC circuit.
This circuit was found in a 2006 documentation. Its purpose is to control a servo system in which...
Raytheon's used operational amplifier is rare today, but the configuration can be adapted to use...
This alarm, from a 1996 magazine, can be fitted with two BC548s in the original configuration...