Hi Guys

I became a member yesterday with the intention of building my own projector, after being on the Internet for some weeks looking for information. After some thought I decided to pay for the membership as it seems that this is the place to be if you want to approach this project seriously.

So I figure that I would start the project by defining the light source. I have been looking into to this Halogen 500W from our local hardware shop. The reason for considering this compared to the recommended MH lamp form LL is the availability and price outside US. You can purchase the compelte lamp for less than 10$ including reflector. A replacement bulb is around 2-3$ USD

I’m also considering to use an 7” Hi Res LCD for the project to make the box smaller. I imagine that the square area of the LCD pretty much matches the halogen lamp. Would it be an idea to connect the lamp and LCD with a tunnel with mirror finish inside and proper cooling? I know I need to have 2 Fresnel lenses one before and after the LCD to make things work.

Is this a possible way?

It doesn't look like a point light source to me. THerefore, you won't get much light past the first fresnel. I don't think it'll work. THe reflector doesn't look like a spherical one, and also, the colour temp of it isn't probably right either.

Ok, I get your point about the colour temperature. What is the preferred colour temperature?

I know the light source is not pointing; witch was the reason for suggestion a tunnel system with mirror finish for guiding the light towards the LCD. As I understand it’s an advantage to have a homogeneous light source with parallel light path trough the LCD, correct?

I have an old OHP with some optics in front of the bulb I assume this is for collecting the light towards the Fresnel lens. Could that be of any use, or should I rip the arrangement from the OHP.

One of the thing that you will have to watfh is the heat comming off your lamp it will be very difficult to get red of. Thoses lamp give out a lot of heat

The general problem with the worklight is that light will be coming out of it in essentially random directions. This means that much of it strikes the LCD at angles that make it much more likely to be absorbed than to pass through. This causes more heat on the LCD. In addition, light that isn't within a few degrees of perpendicular through the LCD (or fresnel if using unsplit optics) won't hit the triplet and won't be projected anyway. The OHP setup is your best bet. It's already designed for projection and many have used them with success.

No, you see, the first fresnel (collimator) will only let light at certain angles pass through, which is light at the angle coming from the point source focal distance. The tunnel system will get more light to the fresnel, but the fresnel will still reject most of it, as it is hitting it at the wrong angle. Light hitting the LCD at different agnels isn't the issue here, as the light passing through the collimator fresnel will be parallel anyway. The problem is getting a lot of light passing through the collimator, which wont happen by
tunnelling" the light.

I used one of the workshop lights to test out my pj. It is wayyy too hot. Black burning spots all over my lcd, not good

Could the heat not be prevented by folding the light path?

Ok, based on your advise I will look into MH source instead.

I just found a BenQ FP567S brand new delivered at my door step for £125 including shipping, should be a fair deal? - At least I'm sure that the LCD panel is unharmed.

Is it worth the extra money for optics to go for the 17” setup instead of the planned 15”, The availability of 15” monitors in DK is very poor.

don't use those i posed that question and tried one before getting the LL stuff nearly mealted my fensel and my lcd in 10 minutes with 4 80mm fans on it

I agree with Shivers. I used mine to test out my pj and it is crazy hot. You need to place the lamp at least 7" away from your rear ferensal. As long as you have the lid on with the slot on top of the box to allow air to pass over the lcd screen (LL specs), you can run it for a few hours with no problems, but the color is crap and the image is dim I'll try to post pics later showing different output using the halogen and the T-15 lamp setup. The difference is night and day.

That being said, I did use my 500w halogen reflector for my t-15 bulb. I cut an oval to accomodate its size on each side and for me, it worked better than the pro reflector. but I am not a percision craftsman and the hal-reflector was much more forgiving on placement.

Are you saying you compared the pro reflector and this halogen reflector and found the "hal-reflector" better?

For me, I found that I had a more even distrobution of light.
With the pro reflector, I need to bring my pj forward to the 7-9' range from wall and scale my image down for movies to be able to fully see the darker parts of movies.

With the craftsman hal-reflector, I was able to move my pj to 11' from the wall and project a 9'L x 8'H image/movie and with the more even light distro and larger screen size the darker parts of my movies came out alot better and was easier to make out.
If I can ever figure out how to shrink my pics to attach, I'll post some.

ok, I think I figured it out. this is before I cut it to fit the bulb, the next pic is of what I have at the moment. I still need to raise the bulb a bit for the top to get proper light coverage.

here are a couple pics using the 500w halgen. the pj is about 7-8' from wall and the control board is
still in the way because I had yet to extend the ffc. These are taken with the same camera in a different mode because the pictures wouldn't take using the one above.








hope this helps folks to see the difference and get a little hope back if they have become discouraged
after testing with a halogen/floodlight set up.

I hope to post a compairison screen shot soon, but can't atm as I just got back from surgery and can't lift anything heavy.