A circuit is disclosed for detecting and eliminating the buildup of snow
and/or ice on the viewable face of an LED traffic signal lens. The
circuit measures the ambient temperature within the LED signal, and when
the temperature falls to a level where snow and/or ice accumulation can
occur, the circuit begins looking for snow and/or ice buildup on the lens
of the LED signal. An infrared LED transmits a signal which is reflected
when snow or ice is present on the lens of the traffic signal. When the
reflected signal is received by an infrared receiver, it sends a signal
to a microcontroller, which analyzes the signal to determine if it is a
valid signal. If it is, a heater is turned on until the ice and snow are
removed.