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.
In the figure we have a practical circuit for use with a magnetic transducer. The 20 M ohms...
Based on the well-known LM3909, this LED pulser circuit was found in American documentation from...
This circuit was found in old documentation but uses components that are still common. The circuit...