It's probably been brought up, but the search feature doesn't allow searches under 4 characters. Anyhoo.... I'm Jerry. I just bought the plans the other day and wanted to ask a few questions. I've read through several threads and my mind is spinning with ideas. I've done a lot of modding to RC cars. Mostly the mini's and micro RC's. Truth be known, I love miniaturizing everything. While dabbling with my RC's, I've come across the new power of LED's. They're getting more and more advanced. While they seem to shoot an extremely long distance, I'm wondering if having them grouped (like http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...7913146068&rd=1 ) would alter the projected picture. Because my finished project will be a rear-projection tv, I'm wondering if I'd need all of that light power suggested with the original plans? I'm looking to take a 7" LCD panel and only enlarge it to 30". Might not make sense now, but I promise to have plenty of pictures once completed. I'm hoping there's a way to add a low-heat light so my final project won't require a fan----only vents. Any help would be greatly appreciated.

If they've never been tested, that's ok too. They're affordable enough where I can give it a go. And if by chance LED's won't work at all, what would be the minium size/spec light bulb that I'd need for a small rear-projection tv as described above.

Hey Joe,

Welcome to Lumenlab.

You can find the answer to your question in this very useful FAQ

Lumenlab FAQ

You will be better off going with the regular bulb.

Hope this helps a bit.

Welcome to the forums Jerry.

Thanks you guys. Glad to be here.

I really think with the power of the new LED's that it's possible to accomplish a low-heat light source. The old LED's only put out 2-3 lumen's/per. Wouldn't 10 - 120 Lumen Lumileds be plenty of light for a small rear-projected TV? Here's more info on the NEW lumileds http://theezine.net/articles/47/Lumileds-A...ght-Source.html . Low wattage, 100,000-hour life and low-heat would make these ideal for what I'm hoping to accomplish.


Doing some research on the new lumileds that put out 120 lumen's each, I came across this and thought you guys might find it interesting. http://www.insightmedia.info/news/LumiLeds...etProjector.htm

OK even if you could afford to do it, you would need a custom lenticular array to get all of your light going collimated through the panel. Diffusers don't work well in projectors so a real lens array would be necessary. Also of note is that LEDs have horrible color spectrums not at all like sunlight, which is ideal for our application.

I was thinking about trying a rear projector as well. Some thoughts/hints:

First, consider a size bigger than 30", even for a rear projector. A 30" CRT television is both cheaper, clearer, less work, and takes up less space. Increasing the size also gives you more space to work with.

Second, heat rises. In the project thread are a number of pjs that are vertical, with a mirror so that the lamp is on the bottom. The engineering difficulty is that the heat rises into the LCD, which is the main part that needs to keep cool. I considered and rejected alternative lighting sources. MH lamps have a high ratio of lumens to heat generated. The heat can be handled.

With a rear projector design, the lamp can be placed anywhere. Using a 250W bulb with presumably less heat, and putting the lamp at the top of the stack, you might create a chimney effect, where heat rising through the top draws cool air from a vent at the bottom.

Third, use Lexan instead of tempered glass as a heat shield. It has insulating properties that might help protect the other electronics.

Fourth, the second heat source is the ballast. The electronic one is much lighter and cooler than a magnetic ballast. Keep it out of the heat path of the lamp. Maybe mount it outside of the box. It does not require fan cooling, just ventilation.

Fifth, in between having a fan and going fanless is the option of using a quieter fan which pushes lower CFMs. As a half-measure, you could just try to reduce the cooling requirements to the point where you can use a quiet fan. The quieter fans cannot be heard if you're more than a foot or two from the pj, and even then, aren't noticeable. If you can't hear it, does it count?

I would be interested in how you handle the screen problem. I haven't figured out the right material yet. (You project onto the rear of the screen, letting it show through to the other side, yet it has to be strong enough that little kids won't put their fingers through it. Making and stretching it is also a head scratcher.)

There are several sources out there for rear projection screens. Which one would be best for this setup, I couldn't tell you.

I've decided to go ahead with the 15" projector to get myself familiar with the process. I hope to later move onto the project I originally purchased the plans for. After looking through everyones AWESOME designs, it looks like I'll be the first to make a custom fiberglass enclosure. WooHoo! I'll make sure to take pictures.

I knew my 30" rear-projection screen idea would have a few of you scratching your heads why I would want something like that. It's a custom fiberglass project I had in mind for my sons room that would require it to be hung from the ceiling and a 30" CRT would just be to heavy for me to trust.