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350 Projector bulb power source? Answered

Hey guys I recently salvaged the bulb from and InFocus LP1000B projector. I want to use this bulb as a light source but am not sure how to go about this because I do not know the voltage to run the bulb at or if the power to it needs to be limited somehow. From my research I believe it is a 350 watt Metal Halide bulb. Thanks for any help.



5 years ago

Do not confuse the metal halide lamp ( a gas arc lamp )
with the halogen filament ( resistive conductor lamp )

Halogen is heated to a vapor from the wire filament heat and light production
and re condenses back on to the filament when turned off reconstituting
the integrity of the structure before the next use.
This form of light ts very bright with lots of infrared and can act
as the desired point source for a lensing system but
is saddled with the shortest life span before the filament burns open !

The high pressure metal halide gas lamp
needs.a high voltage trigger spark to ignite ie ionize the gas
and start current flow that must be limited by a ballast.
All forms of gas current flow is only limited by the physical enclosure
thermal integrity as ionic generation can continue to form
ever increasing plasma..
It becomes a race between ionic consumption the electrodes
and thermal melting or cracking the glass enclosure.
The ballast is a magnetic current limiting device that returns
the limiting energy back to the gas during the AC zero transit passage.
Halide gas arc lamps produce an abundant blue spectral light in a small
area to akin to a point source also good for a lensing system with
simpler cooling requirements.

Jack A Lopeziceng

Answer 5 years ago

I think, in the absence of any markings on the bulb, and also assuming the parts inside the bulb are invisible, or cannot be seen because the glass is frosted, or whatever, I think a measurement of the cold resistance across the terminals of the bulb, will be very different for halogen bulb versus metal halide bulb.

The halogen bulb has a filament, so when cold, electrically it looks like a short, and the ohmmeter measurement will be just a few ohms.

In contrast, the metal halide is some kind of discharge lamp, so when it is cold, its gas is not ionized, and it looks like an open circuit, and the ohmmeter measurement will be infinity ohms, or you know, out-of-range.

So just a simple cold-resistance measurement might be sort of an easy test to help figure to what kind of bulb it is.  I mean for a bulb without markings and without visible insides.

Of course a halogen bulb with a burned out filament also looks like an open circuit.

Jack A Lopez

5 years ago

Hopefully you have not yet discarded the rest of your salvaged InFocus LP1000B projector, because it likely contains the ballast circuitneeded to make this lamp work.

I don't really know anything about driving metal halide bulbs either, but you know, this might be a good place to start:


5 years ago

Typically there are marking on bulbs that will tell you what voltage is needed. Then all you need to do is divided the wattage by the voltage to know how much current it will draw and make sure the source can handle that. Chances are it will require mains power. If you still have the projector i suggest pulling the light socket out and using it. You can also look to see if the socket is wired directly to the mains power input or if it's wired to a power supply inside the unit.