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.
We found this circuit in a Motorola manual. The circuit has the capacitor charging at 15 to 30 V,...
This RF circuit measures transmission power from 0.25 W to 10 W. The maximum frequency depends on...
Two tone siren (CB9085E) This circuit was found in a 1980’s Radio Electronics. The signal must be...