Driving the highway with your high-beam headlights can really increase your visibility, but can be a blinding hazard for other drivers. This simple circuit can be wired into your headlight switch to provide automatic switching between high and low beam headlights when there is oncoming traffic. It does this by sensing the lights of that traffic. In this way, you can drive safely with your high-beams on without blinding other drivers. Automatic Headlight Brightness Switch Circuit Diagram Parts Part Total Qty Description R1 1 5K 1/4W Resistor R2,R3,R4 3 5K Pot Q1 1 NPN Phototransistor Q2 1 ...