Monday, April 4, 2011

Projector Update

I finally finished the project, i am quite happy with the results and now have plans to improve the concept with brighter light sources. Im thinking either 12v hid automotive lamps or higher power leds.

Control Board

The control board consists of a pic12f675, a relay, npn transistor, a protection diode for the relay and some resistors... nothing particularly special.


#include <htc.h>
#define _XTAL_FREQ 4000000


void main()
    TRISIO = 0b111100;
    ANSEL = 0;
        GPIO = 0b000010;
        // wait for power on signal, 5 seconds long
        for(int x = 0; x < 2000; x++)
            if(GPIO2 == 0) x = 0;
        GPIO = 0b000001;
        // wait for ~1 ms pulses to stop, after 100 ms of nothing turn off
        for(int x = 0; x < 100; x++)
            if(GPIO2) x = 0;

High Power Led

The led and power supply came in, i wasn't expecting how bright these things would be. Everything came together perfectly somehow...

I mounted the led onto an aluminum heatsink with some screws and some thermal silicone adhesive, to mount the whole thing into the projector i removed the top part of the bulb cage and cut out the section that screwed onto the projector. I happened to have a collimator lens i salvaged from another projector that fit on top of the reflector, with the reflector and lens siliconed down it was ready to install. A note of warning, the power leds tend to have a silicone lens injected over them which is quite fragile and easily peeled off. I almost had this happen when my reflector came off and the silicone i used bonded to the lens!

Its not quite as bright as the uhp bulb but that could easily be fixed with an led with a higher output

Power Supply

The power supply was based on an st micro TSM101I voltage amperage controller, i used a simple hack using a 100k resistor and a 10k potentiometer to fine tune the amperage supply so the led isnt over driven and die prematurely.

At 1.7 amps the heatsink provided (if you can call a thin piece of aluminum one) got quite warm, i found an aluminum heatsink of the perfect dimensions. I siliconed the heatsink down so it wouldn't shift and mounted the power supply using silicone thermal adhesive


Surprisingly everything worked perfectly, the projector turned on and off just as it would before. A slight disappointment was the fact that  the led was not as bright as i hoped it would be, it ended up producing an image about as half as bright as it originally did. This is with the brightness of the projector turned all the way up.

The projected image is a bit brighter and has proper color, my camera sucks for these types of situation.


For about 50 dollars (including consumables) i retrofitted the projector in about 2 hours of solid work and 4 or 5 hours of figuring out the basics of pic micro controllers. For a bit more money a much brighter led can he had that would make this more worthwhile. Considering how much longer an led will last compared to the ~2000 of a uhp lamp and the power savings. Power loss from the conversion taken into account powering the led comes to about 30 watts, one quarter of the power consumed by original bulb.


  1. Cool project!
    I've thought about this sometime but never had a chance to do so.
    I'm wondering if you could share information about what projector it is and what LED that you've bought? The HID light could be working really well. I think it's a great idea!



  2. Where did you get the LED?? It looks like you are losing a bunch of light, maybe a reflector would help, at least a little bit.

  3. I'm not sure where he got his LED but you probably could find one here.

  4. the components i got from dealextreme are:

    the projector is an old Phillips bSure XG2, the interface for the high voltage board appears to be the same for Phillips projectors from around the same time, 3 wires, one ground, one carries the signal from the projector and the other from the hv board

    with some poking with a dmm and oscilloscope i figured out that the projector gives a 5 second long pulse to signal the lamp to ignite, when successful the hv board gives an active low signal and the control board produces a square waveform with 1ms pulses which continue until the lamp is to turn off, the hv board then gives an inactive high signal

  5. This is an amazing project, I have been thinking of a similar hack. They have some pretty bright, new LED's out there I can't wait to try.
    Thank you for your intuitive breakdown of the project.

  6. If you were to upgrade this, I would go with this LED:

    It is a 90w LED produced by Luminus; very popular in the homemade flashlight building communities for its sheer power.

    It costs a lot more but you get what you pay for. I would love to see a projector with this LED in it.

  7. surprisingly enough the led was only about 500 lumen dimmer than the stated 2000

    this is being ball parked using my lux meter though at 1 meter in the hot spot, at 1.6 amps i was reading about 1600 lux tops

  8. This is really good stuff. I was planning on doing this with some older projectors I have.

    One suggestion, you may want to use a fresnel lens for the light. Because the LED's are not a point source, there is much too much scattering and at the short focal length you have, a regular lens may not be putting all the light output into the output path.

  9. You might be able to get some extra brightness if you can figure out how to get the IR filter out of the way. I did a similar project a few years back using a car headlight bulb. I couldn't take the IR/UV filters out because of the bulb I used, but I figured out how it could be removed. I got another projector with a good bulb before I got around to seeing if I could put an LED in my other one, so I never got around to trying it.

    Awesome hack, thanks for sharing!

  10. i already have some ideas about using a light tube and fresnel lens to prevent spillover, but i have a telecine to finally finish and a reprap that's in a box urging me to assemble it afterwards

    i might try using discrete red blue and green led emitters on each lcs panel on a projector with beamsplitters that are fubar

  11. Hi Dcroy,

    I have a red, blue, green fujitsu projector I have been wanting to convert to LEDs for a few years. I'm now re-inspired by your project. Would it be ok to run a few questions by you once I get started on the project?