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 circuit was found in a 2005 Linear Technology sensor manual. The circuit can function as a shield...
In its original version of a 70s manual, this integrated amplifier, which is uncommon today, was...
This interesting FET-tester circuit was obtained from an old American documentation. The bipolar...