Abstract: A circuit for use with optical inspection lamps, e.g., tungsten-halogen or Marco lamps, in semiconductor fabrication machines performing ADI and AEI operations, that will lower the operating voltage of the lamps when the machine is not being used by an operator, while providing full light intensity during optical inspections. The circuit is coupled into the Marco lamp power supply and contains two micro-switches, each containing two sets of switch contacts normally configured with one set closed and one set open to render one micro-switch closed providing the operating voltage to the lamp and the other open rendering the circuit inactive in this condition. The micro-switches have operating levers that cooperate with indexes which follow the position of cassette elevators that deliver the semiconductor wafers for processing and each of which has an "up" and a "down" position.