A dime a dozen around here, so please shoot it down at will, no offense will be taken.

this plog got me thinking (always dangerous):

http://www.lumenlab.com/forums/index.php?showtopic=22294

using an MR16 for his kids' 7" dvd player based PJ.

having messed around alot with DIY bike lights, why not use some of the same principles for getting better performance in a number of areas: overvolting the lamp.

increasing the voltage on an MR16 will increase light output proportional to the 3.5th power... and reduce life inversely proportional to the 12th power (ouch). A side benefit (while I've seen no quantitative comparison) is that it will increase the color temp as well, giving some better blues than is typical of halogens. (http://www.walamp.com/lpd/files/applicationnotes/isl297a.pdf)

so why not use an overvolted halogen as a cheap alternative to lower wattage metal halides. sure, it may be more expensive in the long run, but it would take a while (even at 300 hrs per bulb) for $2 bulbs to reach the initial cost of a MH setup.

Another thought, the newer infrared-coated-capsule MR16 halogens could be even better (albeit at the $12 unit cost) if they exhibit the same overvolt characteristics as standard halogens (an unknown at this point).

Lastly, I think a narrow spot MR16 could be used in a folded design to eliminate the collimating fresnel while removing most heat issues of halogens (just by placing the bulb far from the LCD). In a vertical fold design... a few mirrors, about 15V, and (if needed) a soft focus lens for removing striations and halos in the spot. pretty simple, now what is wrong?

The make a nice MR16 with a higher color temp and shorter life.

http://www.bulbconnection.com/ViewItem/bcr...C%2F3/item.html

The real OHP lamps might still be better because the reflectors are made to diffuse the lamp arc better.

http://www.bulbconnection.com/ViewItem/bcr...%2FFA/item.html

one more.

http://www.bulbconnection.com/ViewItem/bcr...c/ELH/item.html

The last lamp list the CRI at 100 which I have been saying for years, that the Halogens lamps make great color.

Color temp can be adjusted at the LCD or the screen by adding a little blue. I think most people would say the blue from a Halogen looked better than a MH lamp.

OHP bulb life and expense always annoyed me... I remember finding somewhere that the light output was not significantly greater than an overvolted 75W standard MR16 either, but I could be wrong there. A 3050K CCT 75w MR16 overvolted 20% will be ~3260K CCT put out twice the light spec'd light, and have a life of ~450 hrs (4000/(1.2^12)). It is a tradeoff between expense, life and output... I think the specialty bulbs (OHP, microfilm, etc.) may just be 'overvolted' by design to get the higher CCT and resultant shorter life. Would much rather spend less than $2 and do it myself with such short bulb life! Having said that, the ELC 500 hr bulbs seem interesting... 3400K CCT, 500 hr life, 250W... no indication of the beam pattern though. You could really use just about any beam pattern though... a spot could be used without a rear fresnel, just placed further back (spot reflectors are not that efficient though)... a flood could either be used with rear fresnel, or with an offset parabolic reflector (the 60 deg wide flood would work nicely set at the focal point of one of those small satellite dishes (offset parabolic reflector)... just need to figure out how to mirror the surface cheaply). oh well... that's the next project... gonna show that CFLs can work with a 15" first