im thinking of making a projector... i have played around with LEDs before, so why not try LED lighting? (no need to get a ballast and everything, or worry about UV rays)

i dont really mind having a 300-600 lumen projector('ve been looking at the cheapo Olen projector that has a 300hr 300lumen $30 bulb...)... thus LED seem to be somewhat good choice... want to keep the budget under $200...

I bought a used HP 1502 for $50


from here, having a single SSC P7 LED seems to be a good choice

$20


it said it included the heatsink base... do you think i need to have a fan running? i want to minimize the amount of stuff i wanna buy...... an alternative might be a bigger heatsink instead of a fan...

stuff i need next:
1) the $70 kit from lumens lab (3 fresnel lenses)
2) driver for the LED(2800mAh, 3.6-3.7V) ... any ideas? i've seen one on a UK site for 28 pounds...
the same site for the LED sells a 3.5-3.8V 2A led driver.. less heat i guess, but less lumens
3) reflector.... any ideas?
4) tempered glass
5) possibly a heat management system(fans, heatsink..)

total cost = $50 LCD + $70 kit + $20 LED + $10 tempered glass + $10 reflector + $10 LED Driver + $30 for wood and wires/powerplugs/misc~ $200

im guessing that i can follow the dimensions from here without any problems...

any opinions?

another question: do you think its worthwhile to get multiple SSC P7 LEDs for higher lumen output?...

to be honest you wont be getting 900 lumens on screen from that LED, after its been through the lenses LCD etc, the brightness on the screen (the wall for example) will be very very low. when you say you don't mind having 300-600 lumens, this seems to be a very high number. The lumenlab projectors get around 100-150 lumens with a 400w bulb, but with an LED its going to be much lower.

With a 900 lumen led, you will get around 9 lumens on the screen.

As was mentioned above, you should only expect to see less than 10% of the light pass through the lenses in a DIY projector, making it to the projector screen.

Nope, it's less than 1%

My bad. I thought that the average was 5% and some projector builds had been documented as having 9% of total light reaching the screen.

No, the max I could get out of my 38,000 lumen bulb was about 300 lumens. Which is less than 1%

For my 575 watt , 49,000 lumen bulb was 500 lumens which is just about 1%

Maybe I'm just getting LCD transmission mixed up with total light reaching the screen. I know it's been quoted that less than 10% of light makes it through the LCD.

Well, the 1% (though dismal sounding) is taking into account some issues that LED lighting won't have.

A typical MH lamp throws light in nearly a full sphere, whereas an LED has a distinct viewing cone, due to the lenticular nature of the LED package itself. As such, much of the initial losses of light that doesn't go anywhere near the LCD can be avoided, or at least drastically reduced. You can think of the LED as having a decent precondenser lens right off the start.

In a typical radiating lamp, you can get maybe 10% of that light to hit the LCD, including that which gets there via the reflector. It's probably less than that. With an LED, you might be able to up that to 60% or so with just the right viewing angle on the LED package. Say 50% to be ont he safe side, plus it makes the math easier. This is still much better than a regular lamp, however, the number of LEDs that can put out 20,000 lumens is restricted to approximately zero.

Once the light hits the LCD, you can get maybe 9% of it through. Yup. 9%, and that's if the LCD is on full white. That's also a really good LCD, 7% is probably closer to the median, with many people reporting 5% or so. So this means from your typical radiating lamp, you get less than 10% of less than 10% -- less than 1% total.

So, from your 900 lumen LED, you're looking at 50% of 7%, or... about 31 lumens. With a really good build, you might be able to get that to 50 lumens, but I'd bet real-world, you're looking at 20 lumens or so.

Yeah, that sounds really pathetic, but it's probably watchable in a completely light-controlled room.

There are LEDs which can be made to suit hte purpose, but you're not looking at a cheap build anymore. By the time you're looking at these kind of LEDs, you're also looking at signifigantly more money.

The cheapest light source that works is probably an OHP lamp and ballast. Still not great, as these are typically halogen which is less than half as efficient as metal halide, but it does work.

Well most Lcd's only let through around 5%. Then you have a piece of tempered glass or lexan that absorbs 10%, Fresnels that absorb 10% each and a triplet that has 3 pieces of glass that absorb about 10% each.

So start off with 38,000 lumens. After lexan you have 34,200. After first fresnel you have 30,780. After second fresnel you have 27,700. After Lcd you have 1385. And then after triplet you have 969.

Now that would be "IF" we could harness ALL of the lamps 38,000 lumens. But even with the pro Reflector we still lose a lot of light. So we end up only using around 1/3 of the available lamp output.

This knocks us right down to the 250 lumen mark.

whoops

i guess i can still live with 5-10 lumens..

now is to decide which lenses to use.. the LED probably has a viewing angle of 120-140...

do i need a lens like this glass optics to focus the light to a single beam?....

or just use no lenses(besides the fresnels) and place the LCD like 3 inches away from the LED... (half angle = 60 deg, requires 3inches to hit a spread of 6 inches (15 in LCD = 12 in x 9 in)

For a 120 degree viewing angle, you may want to use a single glass optic to reduce that somewhat, and make more efficient use of the light, however this is done in a manner that is very similar to a regular build, so you could start with just hte fresnels and projection triplet, then refine from there.

If you get 5 lumens out of this, I'll be surprised though...

thanks for the info... i'll probably do this in december/january(winter break for me, can work at home)..... will post how that goes...