DIY Video Projector Part II

[ace3000_1]

Is the beam wide enough to cover a LILLIPUT complety at a short distance.(8 or 9 inchs).

heya chase, this isnt a parabolic reflector, its an eliptical so it will work with a condenser, i tried it out with a condenser and a frensel and it works fine, though i did get blind from it lol.

The new comercial projector have a smaller hole for the lamp and you cant retrofit a cdm in it.

Ya very true, and this one had a hole too small too, u have to cut it out for the cdm-t to fit as i did in this one.

Trev

[Altec]

Originally posted by mathias
I really don´t understand what you mean ? I hope you or someone else can explain this.

Here is some exemple what the lumens output of some bulbs are:
50W 12V Halogen 4000h 930 lm
100W 12V Halogen 4000h 2400lm
250W 24V xenon-halogen 50h 10000lm
400W 36V xenon-halogen 50h 14500lm
150W HQI 12000h 12000lm
250W HQI 12000h 20000lm

Sure you get a brighter beam with a reflector, but not more lumens. When you use a reflector the light beams concentrates in one direction and light what goes in one direction is measured in candels not lumen.

If you put a 1000lm bulb in a reflector and then change it to a 20000lm bulb, which is brightest ?

here
http://donsbulbs.com/cgi-bin/r/b.pl/enh_ansi.html

"ENH ANSI bulb specifications:
--------------------------------------------------------------------------------

category: Projector
volts: 120
amp/watt: 2.08A / 250W
base: GY5.3 - Oval, 2-pin; flat .7mm x 2mm; 5.3mm centered
(found on high voltage MR bulbs)
glass: MR-16
filament: CC-8
m.o.l.: 1-3/4 inches
burn pos: burn lamp in Base DOWN to HORIZONTAL position
lumens: 15000 initial lumens
color temp: 3250 degrees Kelvin

notes:
Beam Angle: 25 degrees
Dichroic Reflector
Enlarger Lamp
fd:5.6
Multi-Facet Reflector
mod
Photoflood
Photoprinter Lamp
Rim mount
Reflector Multi-Facet
Tungsten Halogen "

[mathias]

When it comes to the lumen output from a halogen bulb it´s true that you can get the same as a HID-lamp, but not with the same wattage. Halogen bulbs give max 37lm/W and HID 80-100lm/W. The halogen bulbs they use in slideprojectors and oh-projectors are not real halogen bulbs, they use a mix of xenon-gas instead of krypton, this give more lumens but less lifttime.

Here are some exemples of same wattage bulbs:
250W 24V xenon-halogen 50h 10000lm
250W 24V xenon-halogen 300h 8000lm
250W 24V halogen 2000h 5000lm

As I have said before the filament in a halogen bulb is smaller than the arc in a hid-bulb, this makes it much harder to control the light from a hid lamp, you need a bigger reflector with a hid-lamp than a halogen-lamp if you want use all light from the bulb. You can infact compare the halogen (12V-36V) filament size with a uhp-lamp arc size, they have about the same size and if you then compare the reflector size you find that they also are the same. This is why I recommend the PAR30 reflector it´s made to handel 10mm arc-sizes.

[mathias]

Who said we cant retrofit out a pro projector with a cdm-t bulb, i have and it works fine.

Hm.....maybe because you change a MH-bulb to another MH-bulb, if I was you I had put back the lamp-modul in the projector and tried to start it. Are you sure the reflector is eliptical, it looks very parabolic to me, you can get the same collecting effect to a focuspoint with a parabolic-reflector.

When it comes to do the same on a UHP-lamp modul, I can only say one thing, forget it. The reflector in a UHP-lamp is really small mine is 37mm (1.45") wide and 37mm (1.45") high and the cdm-t lamp is 20mm (0.78"), not so very much left of the reflector after you have cut a 21mm hole in it.

[Altec]

Originally posted by mathias
When it comes to the lumen output from a halogen bulb it´s true that you can get the same as a HID-lamp, but not with the same wattage. Halogen bulbs give max 37lm/W and HID 80-100lm/W. The halogen bulbs they use in slideprojectors and oh-projectors are not real halogen bulbs, they use a mix of xenon-gas instead of krypton, this give more lumens but less lifttime.

Here are some exemples of same wattage bulbs:
250W 24V xenon-halogen 50h 10000lm
250W 24V xenon-halogen 300h 8000lm
250W 24V halogen 2000h 5000lm

As I have said before the filament in a halogen bulb is smaller than the arc in a hid-bulb, this makes it much harder to control the light from a hid lamp, you need a bigger reflector with a hid-lamp than a halogen-lamp if you want use all light from the bulb. You can infact compare the halogen (12V-36V) filament size with a uhp-lamp arc size, they have about the same size and if you then compare the reflector size you find that they also are the same. This is why I recommend the PAR30 reflector it´s made to handel 10mm arc-sizes.

Yes there are diff halogens. Example. Standard halo flood light 100watt is around 1400 lumens 4k hour bulb, no special coated reflector. Now like you said diff gasses BUT more importantly the ENH uses Tungsten filiment. Which can be very small and run very hot meaning small reflector (under 2") with higher lumen per watt output. Tungsten and xenon halo's arent house lights also as you said. They (PJ bulbs) burn out faster, this one in 150hours (vs 4k from standard) due to more heat from higher output. The pj bulbs reflectors remove IR/UV they are actually a FS dichrotic cold mirror. MUCH better then hot mirror for removing heat from visible light. I dont know why ALOT here think heat mirrors are the answer. Heat mirrors not only dont remove as much heat from light, most only doing a 25% diff to pro ones doing upwards 60% but they loose more of the visible spectrum due to passing through mirror coating. Better to reflect needed light and avoid absorbtion. Most ALL pro projectors use cold mirro arrays to handle heat in small enclosures. It "can" depending on grade of mirror reflect on avg. 90% visible and remove upwards 85% heat per mirror! They incidently do get "hot" but were named cold mirrors for their ability to remove MORE heat then HOT mirros do. And cause they reflect cooler visible light more efficient. Hot mirrors are toys for laser guro's primarily. Sorry long post. LOL.




Good read for the diff in bulb types.....
http://www.pti-nj.com/obb_lamps.html


"Tungsten Lamps

Technical lamps consist of a coiled tungsten filament mounted in a precision glass envelope. The envelope may have a vacuum or, more commonly, be filled with an inert gas such as argon or krypton. Typical technical lamp operating parameters are 2.5 to 12 volts and .02 to 1 amp. Color temperature ranges from 2,200 to 3,000 degrees Kelvin; lamp life may be as high as 30,000 hours.

Tungsten-Halogen lamps feature a tungsten coil filament mounted in a quartz glass envelope that has been filled with an inert gas plus a trace of halogen (normally bromine). This gas creates the “halogen cycle”: tungsten that has evaporated from the filament combines with the halogen gas. Convection currents within the bulb carry this gas to the quartz wall where it is cooled and then returned to the proximity of the filament. The heat of the filament causes the tungsten and bromine to separate, and the tungsten is then deposited on the cold portion of the filament.

This regenerative process prolongs the life of the filament considerably, and also eliminates blackening of the bulb by preventing the evaporated tungsten from condensing on the envelope. The Halogen lamp color temperature runs from 2900 to 3400 deg. Kelvin and are available in wattages from 10 to 250 at operating voltages from 6 to 24; lamp life ranges from 10 to 2500 hours. Luminous efficiency is approximately 22 lumens per watt.

Tungsten-Halogen lamps must be operated at voltages that maintain an envelope temperature between 250 and 350 deg. C. Cooler temperatures will not allow the halogen cycle to take place, thus causing bulb blackening and shorter life; higher temperatures will cause oxidation of the conductors and lead to premature lamp failure."

So Tungsten is similar to Xenon output per watt just aimed at lower watt range. Makes sense. Cept Halo doesnt emit UV and need that filtering. Xenon more color correct but be carefull with it. The guys link I posted earlier that listed enh spec was dead wrong. Which I can agree with I couldnt believe it myself. thats what my 175watt mh gives! Anyhow even though lower lumen its controled heat removed and focusable. So overall what gets to screen TONS brighter. The light engine is lots smaller too. So...at 22lumen per watt. Enh is 5,500 lumens. By reg. tungsten watt rating that is. Sorry for any confusion. I hate specs that are WRONG.

[ace3000_1]

Hmmm you might want to run up a few tests for yourself on the cold mirror, i have some here thats far more efective then any dichoric reflector ive owned, and thats testing with a pro reflector as i posted a couple of posts ago. A dichoric reflector will only cool the light that it reflects, thus being not all so a large quantity of heat still comes from the light source, now if you run all of your light onto a cold mirror and reflect the visible light to the lcd, all of the light from the source is filterd and yealds a much cooler light.

How to run a cold mirror cold? well dont have a metal backing plate on the back of it as sujested by manny leading manufactures, so the heat doesnt build up on the metal plate at the back of the mirror, redirect it to a metal plate 2inches behind it and the mirror will just get warm, the metal plate will only get hot which u can easily cool with a fan or convection.

Trev

[ace3000_1]

When it comes to do the same on a UHP-lamp modul, I can only say one thing, forget it. The reflector in a UHP-lamp is really small mine is 37mm (1.45") wide and 37mm (1.45") high and the cdm-t lamp is 20mm (0.78"), not so very much left of the reflector after you have cut a 21mm hole in it.

Yeah those new small ones u cant do anything with lol.

And yeah, its definatley eliptical, works fine with a condenser although its focal is abit long for my needs.

Trev

[buzardbuck]

http://www.lightshop24.de/Datenblatt%20LED-PAR38-G.htm


what did u think this one?

[Altec]

"Hmmm you might want to run up a few tests for yourself on the cold mirror, i have some here thats far more efective then any dichoric reflector ive owned, and thats testing with a pro reflector as i posted a couple of posts ago. "

I agree cold mirrors are best. I already have 5 here to test with. One is in now and planning on staying there. hehe. But what you mean by they are better then dichrotic mirros I dont understand. They are a dichrotic mirror. So are hot mirrors. And many other types of special mirrors. Dichrotic just means its multiple layers of diff metal on glass in such a way that it filters and reflects. If you look into it or through it you see the multi colors of reflector from different fine metal layers that are imposed staticly to the glass. Dichrotic simply mean-multi colored. The ENH has a cold mirror reflector now. But I also have it aimed at another 4 3/4" one.



"How to run a cold mirror cold? well dont have a metal backing plate on the back of it as sujested by manny leading manufactures, so the heat doesnt build up on the metal plate at the back of the mirror, redirect it to a metal plate 2inches behind it and the mirror will just get warm, the metal plate will only get hot which u can easily cool with a fan or convection."

Were thinking the same! My pj is doing just that. No backing to cold mirror. Just a 50cfm (HOLLY COW!) fan behind bulb drawing out. I have cool air intake flow directed so it must pass cold mirror first and the hot backside at that. Should work. Yes? I will know tonight, Im THAT close to done. I'll be happy with a bright 5-6' image. From there its on to rear pj with same light engine.

[ace3000_1]

But what you mean by they are better then dichrotic mirros I dont understand

Hmmm was like a kind of figure of speech lol well what i meant to say is that a cold mirror can more efficently cool the light from a source at 45deg as all of the light from the source (reflected and non reflected light) is filterd by the mirror, compared to just having a dichoris reflector that wikll only filter just the reflected light bouncing from the reflector.

All your setup sounds good bud, to give you a helpful idea, why dont you rivet a heatsink on the metal plate thats taking the heat from the back of the cold mirror? this will help keep things cool .

Trev