Automatic lamp switch-over for projector - comprises 2 lamps on servo-controlled slider with first monitored by photocell to switch in second on failure

摘要

The high reliability projector has two lamps on a vertically moving slider held in position against a return spring by a solenoid-controlled ratchet. The light output of the first circuit, so that the solenoid is operated when the lamp output falls. The second lamp is brought into action and the projection can continue. The slider is fitted with a screen to shut off the light from the second lamp to the photocell, and the switching circuit then operates a LED indicator after a time delay. This indicates to the user that the stand-by lamp is operating and that the main lamp needs replacing.