This 80's Hands On Electronics circuit automatically switches from high light to low light when an oncoming car illuminates the sensor. The circuit is powered by the car's own battery.
This diagram was found in the November 1972 issue of Radio Electronics magazine in an article...
This circuit is based on the voltage drop of the diodes in conduction, in the order of 1.6 to 1.7...
This circuit is from an Electronics Now from the 90s. The circuit uses a power integrated circuit...