This circuit is intended to detect when current flows through the opening of a car door. The circuit fires the horn for 90 seconds. The FET can be the BF245 and the NPN transistors can be the BD135.
The purpose of this simple stabilized source, obtained in a documentation from the 70s, is to...
This simple receiver for listening on a crystal phone tunes the range of medium waves. The circuit...
This medium- or short-wave receiver circuit was found in documentation from the 1980s. The circuit...