This set-rest relay uses two SCR and two switches to control a DC relay. The circuit can be used with 5 to 12 relays and power supply must be 2 or 3 volts above the relay rated voltage. This is necessary due the 2 V voltage fall in a SCR on. L1 is a 6 or 12 V lamp with current drawn of 50 to 500 mA and can replace the relay if the circuit is used to teach how a bistable works .
