DIY Video Projector Part II

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I don´t think you have to cool the reflector so very much, the reflector is made to handle very much heat, the orginal 75-100 halogen thing in the middle of the PAR-reflector gets much warmer than a 150W HQI-bulb. I think the only fan needed is a fan that pull the warm air out of the pj-case.

But I think the main reason to use a PAR30 design is that it is cheap and easy to find part for. They have PAR30 bulbs with a coollight reflector in all lampsshop, but you have to ask for it.

A PAR-design use all light you can use from the bulb, and we need all light we can get!

I bought a commercialprojector yesterday, I couldn´t resist, the price was only what you pay for two 15" tft monitors, and that unit is marked with 800 Ansi-lumens, and it´s much much brighter than my DIY-projector even with the PAR30-design, so a DIY-projector will not be brighter than mayby 150-200 Ansi-lumens as most even with a 250W bulb.
 
diyAudio Member
Joined 2003
so a DIY-projector will not be brighter than mayby 150-200 Ansi-lumens as most even with a 250W bulb.

hmmm u might want to bring that up with cruser as his is totally watchable in the day, his must be about 800-1000lm i recon, anyway about the reflector, to me i think the parobolic design u have is the best for the cdm-t bulb, the reason why is because the cdm-t's center arc tube is ceramic, no light can pass through it when using a spherical reflector as its not clear, using a parobolic in the type u have chosen is the best for that bulb as the light from its sides can get freflected forward, in the spherical its blocked when the bulb is at the focal point as the light cant pass through the ceramic center, so realy your reflector is the best and the reason above is 1 reason why its brighter, the other reason is because of the reflectors shape and size, it can capture nearly all of the light at this size there fore giving us a gain of light output, as for the cdm-t being used on a shperical reflector u cant run it at its focal it must be off set either in or out of focus to get the best results so the light can pass under or over the ceramic arc tube, now with a 250w hqi they have clear arc tubes, the spherical reflectors on these work wonders as the reflected light can pass though the arc tube, u wouldnt get much gain with a paroblic reflector of this design on a 250w hqi, being only the light that isnt captured by the shperical reflector caught by the parobolic, then u would also have a problem with a double ended bulb as the socket would cause u a shadow in this configeration, the best reflector to use is an elliptical, they arent cheap and hard to find, only then we will be able to use 90% of the light source, so realy i think for a cdm-t setup the parobolic setup u have designed mathis is the way to go, and for the 250w hqi the spherical is the way to go.

As for the heat it will be very hot, anything that filters or absorbs ir will take the heat, that reflector will get nearly as hot as that bulb after a couple of hours use so an adequite cooling system would be required, thats somthing thats easy to over come with abit of common sence and the right design structure.

Trev
 
diyAudio Member
Joined 2003
I don´t think you have to cool the reflector so very much, the reflector is made to handle very much heat

Very true and so are condensers but that reflector will heat other things up, just like a condenser does, anything metal conducts heat so what u mount that metal too will get the heat from the metal mounting holding the reflector, a cleverly designed metal heat sinking frame would be the go to remove the heat from the source.

Trev
 
ace3000_1 said:


Very true and so are condensers but that reflector will heat other things up, just like a condenser does, anything metal conducts heat so what u mount that metal too will get the heat from the metal mounting holding the reflector, a cleverly designed metal heat sinking frame would be the go to remove the heat from the source.

Trev


I didn't know that the source of such tubes (HQI-TS and CMD-TS)
where not clear, thank you for telling. (I had almost bought a spherical reflector).

About the heat disposal:

What about taking a metal grid:

An externally hosted image should be here but it was not working when we last tested it.


like this and use it in this way:

An externally hosted image should be here but it was not working when we last tested it.



Ok we have to find a way to block the light going up.
 
diyAudio Member
Joined 2003
Well guys here is some info on reflectors, no doubt u would know it and have seen it before, as u see the sphericals can be used as a parabolic if the light source is at half of its radious, now what im going to do is atempt lol to drill a 22mm hole in a large sperical reflector for this cdm-t bulb, i think it will work and the reflectors sure as hell have the right coatings so it should reflect alot more light then when it was used as a spherical.

http://www.awi-industries.com/relectors.html

Trev
 
This is a picture of the UHP-lamp unit in my commercialprojector, surprising they use normal plastic around the lamp and in the lamphouse, so I really wonder if the heat is a such big problem.

Ace if you want to talk about the reflector, please mail me, I don´t use msn (Icq is much better, Microsoft always try to copy things and destroy them).
 

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The Alchemist said:
Mathias I think you hit the jackpot with your par design. look at this profesional lighting (disco) equipment:

An externally hosted image should be here but it was not working when we last tested it.


From this site:
http://www.inter-son.fr/scn800hqi.html


so my question is: where do we get such a high reflective reflector like this one in the picture the alchemist posted?
 
mathias said:
I payed €15 last summer for that lamp. Buy two of them if you are going to take one of them apart. But yes it is not so cheap for a reflector.


What measurements does it have? i am searching a reflector with a max. dia of 70mm at it's widest...

i guess these have 130mm or something, which is too big, cause i want to build a compact projector this time.
 
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