I have a bunch of 400W mercury vapor lamps.

The made is GE. Some of them have capacitors, some do not. Two of them may not be mercury vapor, but probably are high pressure sodium. The reason being that the bulbs are the long and slender. The shape looks like this:

http://www.elights.com/philhpsmogba.html

The strange thing is that for other lamps (big round bulbs), some have capacitors, and some do not.

My question is this: what is the voltage for these lamp? Is it 1 phase or 3 phases? How useful are they for DIY projectors.

Thanks, Nan Null.

Mercury vapor lamps do not have the correct spectrum of light to make them suitable. They typically lack much of the red necessary for use in a PJ. High pressure sodium lamps are also a poor choice due to color spectrum issues.

The ballasts *may* be of some use... are there any markings on the ballast ? There should at least be a make/model # to determine what they are ? Capacitors are used for power correction on most ballasts, but what we've seen is that changing the capacitor on CWA type ballasts will change the power delivered to the lamp. Capacitors may or may not be used depending on the ballast and lamp combination. Ballasts can also be of different input voltages ranging from 120v up to 480v (and possibly beyond...), again depends on the specific ballast. Also some ignitors can look like a cap. Cap's have only two wires (or poles) while ignitors will have three.

gs

I'll check on the make and model tonight. I wonder if there is a projector friendly bulb equivalent of:

http://www.buylightfixtures.com/index.asp?...&ProdID=637

This bulb runs on mercury ballast. The problem is that it's big and has big arc. A small bulb with small arc with a reasonable price would do.

I look at this page: http://www.lumenlab.com/forums/index.php?s...l=mercury+vapor
and see Iwasaki 6500K, however, I didn't see 400 watt type bulb for this.

http://www.eyelighting.com/cleanace.html

(click on the PDF Sell Sheet to see more details)

this is a metal halide lamp designed to fit mercury ballasts. it has a good amount of red as can be seen in the spectral distribution chart and has a CRI of 90. Pretty good. Arc size unknown...

now... just to find someone who sell them... like here : http://www.specialty-lights.com/mt400dl-bud.html

I can see now that they use a reactor type ballast, which sometimes have "optional" capacitors to the circuit...

Can the Iwasaki MT400DL be mounted either way? I am going for a 45 degree mount of the bulb.