US Patent 7535375 Lamp or LED failure monitoring system

A light failure monitoring system using existing alarm panels includes a first circuit capable of turning on a solid state switch or transistor, which turns on a lamp or LEDs. The system also includes a second circuit having a light sensitive device, such as a photoresistor, that keeps the solid state switch or transistor turned on upon sensing light from the lamp or LEDs, and when the light sensed by the photoresistor substantially drops in intensity the solid state switch or transistor turns off, which causes an alarm to sound on the alarm panel. Alternatively, the first circuit may include a second solid state switch to amplify the signal and make it easier to start the second circuit.