Questions regarding replacing lamp in a projector with a h..

HiC wrote:
> If replacing the lamp in a projector with a small, low wattage halogen lamp
> to project through a condenser lens, what I wonder about are the properties
> of the light going through. It's my understanding that projector lamps are
> made to a particular color spectrum - is this correct?
>
> Will any small halogen lamp of the desired voltage/wattage work? Or is there
> more than one "kind" - as far as the kind of light they emit? What about the
> opal diffuser that goes in front of the halogen bulb, is there more than one
> kind or color, or more specifically a particular type I should look for?
>
> Thanks for all input.
>

Mostly you should look for the same make and part number as the old bulb
or assembly, or at least one specified as an exact replacement by it's
manufacturer. Mechanical fit including position and shape of the
filament, reflector shape if any, and wattage are the most important
consideration. Halogen lamps work over a relatively narrow filament
temperature range. They don't have a great range of color temperature
without exterior filtering. Using one of higher wattage is likely to
tax your projectors cooling, and perhaps damage the case or optics. A
lower wattage one just won't be as bright and probably won't last any
longer as the designed unit. You might have the choice of a 115 or 220
volt bulb but it would only make sense to change if you were moving to a
country with different supply standards.

I would expect the existing diffuser should be reused. If you want
special color filtering that can easily be added in front of the
projection lens. No point putting it near the bulb where it has to
withstand higher temperatures. Most "tint" filters absorb the unwanted
energy, converting it to heat. Dichroic filters reflect unwanted
energy, but it has to go somewhere.