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.
This two-transistor MW radio was found in a publication from 1958. It uses one of the oldest type...
Found in a 1988s Radio Electronics, this circuit uses transistors of general use to increase the...
This circuit can be applied to other 3-terminal regulators and equivalent transistors can be used....