Electronic key interchangeable with mechanical keys - switches a load supplied from the mains through a stepping down transformer

摘要

The electronic key can replace a mechanical key without additional wires, and switches a load operating at a lower voltage delivered by the above transformer. It comprises a contact plate connected to an amplifier with high input impedance. The amplifier output is connected through a rectifier to a switching component in series with the switch operating the load, so that when the contact plate is touched, the switch is operated by the hum voltage between the mains live wire and the operator. A JK flip-flop makes possible the switch switching on and off. The amplifier is a field-effect transistor, and the switching component a bipolar switching transistor.