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 transformer of this unit found in an old Japanese documentation can have 22 to 25 V of...
This JFET amplification stage was found in the April 1993 issue of Electronics Now. The input...
This circuit with two power transistors was found in Radio Electronics magazine from October 1960....