Auto-Switchover Upon Lamp Failure


Resident Curmudgeon
Senior Team
Premium Member
Unlike EVERYOTHER QotD, this one is immediately open to everyone regarless of experience or educational status. Only this time. Only this once.

In days of old, let's say primarly in the late 1960s, it was rare to find an A/V projector that did not have at least some provision to deal with a blown lamp mid-lecture. The Overhead Projector especially had several options: spare lamp inside the lamphouse, spare lamp beside and sharing optical path with the primary. Upon main failure, the operator swung a lever, which moved the sockets and engaged the spare. Or the fully-automatic--if the projector sensed no light coming from the main, the spare would be automatically energized.

My question is...did any stage light manufactures ever (attempt to) incorporate this feature? If yes, name names. If no, why not?

And your reward for sitting thru and reading all that, a humorous anecdote. About 1986 my friend came in to work the nex day having run an Altnam Comet* for the first time. When asked how it went, she answered, "it was fine, but we blew a lamp." "No worries" says her ME, "Open the lamp door." "So I did that there was a spare lamp, just like a matte knife blade!"

*I'm thinking it may have been a Phoebus Ultra-Quartz rather than a Comet. Used the same 360W ENX or FLE MR16 lamp.
The Stony Point Light House on the Hudson river is lit by a 12V 5W car lamp (with BIG Fresnel lens - visible for 5 miles) in a rig that has the lamp shorting the inputs to a DC motor, so that when the lamp opens up, the motor turns a carousel that swaps the bad lamp with a new lamp (which will short the motor when it is in place and lit). It is the most simple machine that just swaps blow lamps automatically .

Its like a stage light....if all the world is a stage...?
Well, this thread didn't go anywhere, so it must be time for another anecdote. I wonder if @STEVETERRY ever dealt with a similar situation. And whatever happened to @len ? I hate it when people just dissappear and are gone forever.

Mid-80s, a guy calls the Lighting Rental Shop to rent some 10-12 lights for a business meeting in a hotel ballroom. Totes normsville. After working out the dates, times, prices, he throws me the curveball. "This producer prides himself in never having lost a lamp during a show." Whoop-dee-do for him thinks I. "So how much would it be for all fixtures to come with brand new lamps?" Um, the price of all new lamps? EHGs and EGEs. Now what I didn't know at the time, until discussing it with my seemingly omniscient boss. The prevalent practice at the time was to replace all the E-III slide projector lamps the morning of the first show, then run one test show on them to wade out any early deaths. A couple of considerations here, 1. E-III lamps were like $2-3 each, while EHGs were $20 or so. 2. The slide projectors were easy to access, via scaffold tight next to them, 3. The lamps went into a tray that slid easily in and out of projectors, 4. With three people, one actually changing lamps, another swapping modules, the third passing stuff back and forth, 24 projectors could be relamped in less than 30 minutes.
Anyway, I explained to Mr. Producer that our rentals always included at least 10 percent spare working lamps, and we always rounded up. All new lamps would have cost more than the total rental. Skip to the end of the story...when the rental came back, I investigated carefully; they had not touched the spares. And boy was this company a stickler about getting spares returned, working or not. But that's several more stories for another day.

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