Here is a MH bulb I might try in my 2nd projector. It has 12500 lumens over a 7mm gap. Rated life is 9000 hrs and it is only 150 watts. When compared to my 400 watt bulb it will save me about $146 over the 9000 hr lifetime (about 3 years with full TV watching) in electricity bills (at 6.5 cents per kWhr). The lumens per mm is 1786 as compared with the 400 watt Venture bulb at 1600. And it fits the pro reflector, too. And the low wattage might allow us to do away with the heat shield.

The only thing I worry about is the shape. It looks like the arc may be too close to the top edge, thus distorting the light coming out.

Do you guys have any advice or observations concerning this.

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Nice price and arc length. But the lumen output is so much lower
compared to a 400 watter, that would be a really dim projector.

actually that would probably be a great bulb for an ellipsoidal reflector, which would help the lower lumen output..... and it might work great in the altman reflector.....

edit: if by using an ellipsoidal you could capture 50% of the output (not hard for a small arc lamp I think) that would be about the same as a standard LL build, or at least in the vicinity....

I disagree. The arc should be parallel to a line drawn between the foci
of an ellipsoidal. Ace has nice post regarding this on DIYAudio.

Wasn't that the kind of lamp Rox was intending on using?

quite possible, I was going to suggest going over to diyaudio, seems like they do a lot of lower wattage pjs......but it still seems to me that with a good reflector this should make a decent pj?

No - a Philips Mastercolor CDM-T.

what if you ran the bulb horizontally in from the side in an elliptical?

Then you end up with an area the shape of a strip on the LCD that
doesn't get any light. Rox is having a similar problem with the
little electrode wire that crosses over the arc tube.

I'd recommend trying this bulb with a small aspheric condenser lens from an OHP - or available from surplus sources - and the new LL mirrored spherical reflector. You might be amazed by the results.

I use a 15,000 lumens bulb in my first projector - with a OHP condenser and mirrored reflector - and achieve higher overall brightness and uniformity than I did with my 40,000 lumens T15 metal-halide and IKEA reflector, eballast, etc.

The small arc size really makes a difference if you can take advantage of it...

If you were to cut a hole in the LumenLab reflector and stick this in there, does anyone think that it could be made to work? Perhaps even with a Pre-Condensor lens of some kind?

You can't cut the pyrex LL pro reflector.

a 7mm arc lens could be used with a condenser lens. It's the longer arc lenses that we can't find any real benefit with.

You couldn't drill it with a diamond bit? Perhaps I should have worded that post better.

There may be a way, but it's not like it's just really hard metal or something like that. It's a different material with very high internal stresses, and I believe it's very difficult to cut without it chipping like crazy or shattering.

Hunting around on the web, I found a lot of people asking about how to cut pyrex, and very few answers.

But let's back this up a bit. Why would you want to cut the pro reflector? Is the dia of this bulb too large to be able to get the arc to the focal point of the reflector as it is?

It's good to know someone else has tried these (Rox). I'll see what I can find with his setup. I was planning on using the Pro reflector. I didn't even think of using a condensor, but with the lower wattage bulb it might be a winner. I'll have to start paying attention to that condensor thread.

As I said, my logic is that these approximate a point source more closely. But then again, elgeghast is throwing that logic out the window with the results of his setup. What to do...what to do.

Rox,

Any advice or problems you had with these.

hello ppl,

yes I am stuck with those lamps, plalading has splained whats my problem;

the wire paralell to the burning capsule is making a shadow and this is diming part of my hami. Still working on it.

That's good news! What make and model lamp is the 15,000 lumen guy?
Are you using it now in a PJ?

what size of condenser? surplus shed have them? whats the wattage on yours?

Rox,

could you provide an update on the problem or some links. Can you not just turn the bulb around. How is your brightness? And finally, is there a dark spot in the middle of your projection. My biggest concern is that an elliptical reflector will place a dark spot in the middle.

It's a 400W EVD halogen bulb. So it has some significant drawbacks compared to a MH lamp - lower color temperature, greater IR emissions, and much shorter lamp life. But they only cost $7 apiece. Overall I am much more pleased with the results. I can live with the warmer colors and other shortcomings for the improved brightness - and much less UV to worry about.

The bulb, condenser, and spherical reflector came right out of a 3M 9550 OHP. You can buy these little condensers at various places - Surplus Shed might have one or two, DIY Projector has one, and many others do I believe. The mirrored reflector is much harder to come by - but that's changed now with the LL reflector, which is a little larger than used in an OHP - made for a much larger bulb. It would work, but not as efficiently with a small arc lamp. Still it is probably nearly twice as efficient as a stainless steel reflector.

The biggest gains will likely come from using the aspheric condenser with the small arc lamp. I estimate my OHP light engine to be 3 times as efficient at capturing light and sending it to the LCD than my old 400W T15 MH lamp, IKEA reflector, eballast - the standard LL setup.

Rather than trying to find a suitable OHP condenser, which is designed for an extremely small bulb form factor, I would suggest using the 4.5"x6.5" FL condenser from Surplus Shed and the new LL spherical reflector. This is what SIMUL8R and others have been using already with some intial successes.

You should be able to achieve even greater gains in light output and efficiencies with a smaller arc lamp. But you might need to use a longer FL rear fresnel. If you are unable to fully illuminate your LCD with the 220mm fresnel - you just get a very bright circle - then try the longer FL fresnel which will allow the light cone to spread out more.

And you will need an active cooling system to keep the condenser from cracking. Some small condenser lenses, like those used in OHP's, are made from heat-resistant Pyrex. But most of the larger surplus condenser lenses are made from ordinary crown glass and are very susceptible to cracking when heated up.

Best of luck!

On second thought, I recommend trying to find an aspheric condenser made for an OHP. That will be heat-resistant and optimized for a very small arc size. The surplus condensers - like from Surplus Shed - have very large spherical aberration errors - meaning they likely won't work nearly as well with point light sources or very small arcs.

Here are some sources of aspheric condensers for very small bulbs:

http://www.surplusshed.com/pages/item/l3425.html

http://www.surplusshed.com/pages/item/l3478.html

http://www.surplusshed.com/pages/item/l3467.html

http://www.anchoroptics.com/catalog/product.cfm?id=34

{You want to get a PCX lens because that has a flat side on the bottom. }

So these cant be used with a 150w hqi double ended? What FL should be used? This FL is the distance between the arc and condensor?
Are these condensers heat resistant?

Maybe not. What's the diameter of the 150W HQI bulb? These aspherics were likely designed for small halogen lamps that are no more than about 20mm in diameter, allowing the lamp filament to be placed very close to the lens.

The focal length depends on how close you can get your lamp arc to the lens and the size of your LCD and focal length of your rear fresnel. Right now I do not have a way to calculate the ideal focal length...yet. Nor can I simulate aspheric lenses.

However, RymGB has written a precondenser spreadsheet using thin lens theory that may provide you some guidance:

http://www.lumenlab.com/forums/index.php?showtopic=9849

You need to input the parameters of your light engine components and may need to ask RymGB for some guidance on interpreting the results. I'm sure he would be happy to help you if he can.

The focal length of the condenser will always be greater than the distance of the arc to the condenser. Otherwise the lens would collimate the light into a straight beam, like the fresnel does - which would be too much.

The specific glass material of these aspherics is not explicity defined - they could be heat-resistant or not. But if they were designed for overhead projectors or similar applications, then likely they are somewhat resistant to heat.

Hope this helps...

A easy way to look at the small arc is to ask what is the shortest rear fl that will still let the arc fit in the triplet. The sum of the condenser and Fresnel or a short rear fresnel will give similar results if you pretend that the size of the fresnel does not matter.

so what is the shortest rear fl that a 7mm arc can use?

Well that’s about a 37mm rear focal length

A 37/330=8.91 magnification factor so the arc would be 62.4mm at the triplet if the rear fresnel was 37mm.

We don't have a 37mm fresnel but we can add a condenser lens to shorten the rear fl
I don’t know the formula but it shouldn’t take long.

Can think of how bright your pj would be if you could put your lamp at 37mm from the rear fresnel?

can we say pyrex fresnel

In a two lens system the effective fl is not the same as the measured distance a 330mm rear fresnel and a vary short fl condenser of [blind guess here] 40mm or so might yield a effective fl of about 37mm.[ ROX could do this in one second ]

A Pyrex fresnel would be cool no heat sheild needed you can get them up to 8" or so for less than $100.

The idea here was on how to find a starting point for a two lens system.

You must be talking about some other alien invading 150w hqi. I have both 150hqi double ended and 400 watt single hqi. The glass around the 150 hqi arc as about 3mm on either side while on a 400w its more like 9mm. What your saying makes no sense to me. Using the same reflector I can get the 150w arc much closer to the reflector then the 400 envelope lamp. So the same goes for the condenser lens. The arc on a 150mm is about 12mm wide and 8mm in diameter.

So, the 150w bulb is about 14mm in diameter?

Anything less than 25mm in diameter might work quite well with these aspherics.

Thanks. Its actually about 12mm doing a quick measurement for the 150w hqi. But I think I want to use 400w single ended. which I think is pushing close to about 22mm diameter and about 40mm in length.
But are these condensers heat treated?

Dajyn,

That is the exact model of OHP I currently have... Is it possible to see pics of your setup and get some details on it?

The 400w might work too - certainly the 150w will if the bulb is only 12mm in diameter - that is really small!

I honestly don't know if those Surplus Shed aspherics are heat-resistant or not. You could ask them about the exact lens type of glass - if they know.

Here is a photo:

Click to view attachment

I'll add some details or answer any specific questions you might have...

All the light engine parts including the fan are right out of the 3M 9550 OHP. They really worked great - once I installed a longer 317mm fresnel versus my original 220mm.

Questions, questions, questions....YES!

Did you maintain the same distance from the fresnel to the light source as in the OHP?

Was there a reason besides your lcd size that made you change out fresnels?

Are you using a split fresnel design, or are you using the single design?

Are you using the vari-focal lens from the OHP or the LL lens?

Did you maintain the same distance btwn the lens and lcd as it would have been in the OHP?

Any particulars problems faced gutting the 9550?

I know, a lot of questions, but the more information I garner before I start, the better off I feel I'll be when I start.

Thanks for your time...

Remshan:

The light source to lamp distance was somewhat by accident. I couldn't get the OHP light engine to work with a 220mm rear fresnel. The light cone was too narrow and it only produced a very bright circle on my LCD - the corners were completely dark. Then I replaced the 220mm fresnel with a 317mm and dropped my light engine as far down as I could to let the light cone expand as much as possible. And it worked great! If you have a 15" LCD you will need to use a 317mm fresnel with the OHP light engine, unless you remove the condenser lens, which will cut your light output by about half - not worth it.

I am using split fresnels. My LCD is spaced about 4" from my rear fresnel because of issues with the PCB's and cooling and an FFC cable I had to add which is visible in the upper left corner of the image. However you should keep your rear fresnel reasonably close (20mm or less) to your LCD to minimize light losses.

Yes, I am using the varifocal from the OHP. It is a little "too small" actually. I can fully project the LCD. However, I have trouble gettting uniform focus from center to corner. And since I am apparently using the entire field of view of the varifocal, I have slight curvature distortion in the corners that is made worse by keystoning. So I really don't recommend using the varifocal unless you can tolerate these limitations.

The varifocal to LCD distance was determined through trial-and-error and is probably fairly close to the setup in the OHP.

Gutting the 9550 was fairly easy. I decided to keep almost all the wiring intact. So you might struggle with that a little bit. They use two on/off switches. One is built into the cooling fan and the other is activated when you open the lid on the OHP. I kept those and used a screw to press against the switch in the fan so it was always on. I use the other switch as an automatic shut-off on my projector if someone opens up the front door.

The transformer has two output terminals labeled 36V & 34V. You want to use the 36V terminal for maximum light output. The 34V is for extended lamp life at the expense of reduced illumination.

Best of luck!