Schematic Reference

This is a simple parking light switch. The idea is that you drive your car towards your garage. You shine your headlights at the sensor, which switches on an external light . If you dont have a garage the sensor can be placed on a wall or post, and the external light will illuminate the area while you park and leave your vehicle. The circuit also has manual on and off controls.

Parking Light Switch Circuit Diagram


Notes:
This is a very simple light switching circuit using a single transistor and relay to control an external mains powered light. Relay RLA is drawn with two changeover contacts, but a relay with two make contacts can also be used. The contacts MUST be rated at 240V AC and at least 3 Amp (or higher) to safely switch loads of up to 500 Watts. Once energized the relay latches through contacts RLA1 and the external lamp is switched via contact RLA2.

Setting Up:
Wait until darkness and shine your vehicles headlights at the ORP12 Photocell. Adjust the 100k potentiometer until the relay triggers. Turn off the headlights and press S2 to turn off the relay. The external light should go off. It may be necessary to place a plastic tube of about 1 inch in length so that only light emitted by a cars headlights reaches the photocell. This will prevent unwanted triggering.

The light can also be manually controlled by pressing S1 which will latch the circuit, and S2 will turn off the lamp again.