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, which can act as a shield, was found in a 1969 documentation. The circuit uses...
This oscillator can generate signals from 100 kHz to more than 50 MHz depending on the crystal used...
This simple multivibrator circuit generates a 1 kHz signal rich in harmonics. The circuit is from...