The instant invention relates to an ignitor turn-off switch for ballasts
for high intensity discharge (HID) lamps to prevent damage to ballasts by
disconnecting the ignitor if a lamp has failed or is missing. The ignitor
turn-off switch circuit comprises an AC power source, a full-wave bridge
rectifier circuit, a voltage regulator circuit, a first solid state
integrated circuit as a timer circuit, and a second solid state
integrated circuit as a switch circuit. The second solid state integrated
circuit comprises an optically-coupled triac and light emitting diode
wherein the optically-coupled triac is driven by a beam generated by the
light emitting diode.