Friday, October 7, 2011

LED Projector Mark II

After completing my first led projector mod i was commissioned to do another one, with an even more powerful led this time

This time around i modified a phillips hopper sv10, which had a burned out polarizer i replaced earlier in the year. Thinking the interface would be identical because of the same manufacturer and they were similar models built around the wrong time, obviously i was wrong.

Instead of a heart beat signal and active low feedback the control signal was a simple active high pulse, feedback required a constant 5 volt line to be pulled down. Using my scope wasn't very helpful as i was expecting a squarewave signal (really need a second probe while im at it) but my new logic probe made quick sense of it.

This time around i used a 50 watt led, 32 - 36 volt power supply, reflector and a pack of credit card frenel lenses to play with.

I mounted the led exactly the same way as before: i removed the uhp bulb cage and hacked off a piece that screwed onto the rest of the assembly

Drilled small pilot holes for mounting the led

Then drilled and tapped for 6 - 32 screws

The plastic piece i hacked off was bolted to the top to mount the led at the perfect position.

 A bit of thermal silicone to hold the led in place and give better thermal conductivity

And finally screw into place. My control board is nearly identical to my previous version, with the exception of the extra transistor used to pull the 5 volt line to ground

Alot smaller and cleaner than my last version, also i found a place to pull 5 volts off the power supply removing the need for its own supply.

Im still in the process of testing different lenses but the credit card frenel lenses seem to do the trick... im a bit concerned that it might sag during prololged operation since it is just a piece of cheap plastic.
Time will tell i suppose, perhaps adding a fan to blow over the front of the led is a solution.

So far it is quite a bit brighter than the 25 watt led i previously used, but it does get much hotter and i will need to attach a fan directly to the heatsink i used, seems to get close to 45c right now but that is with the case open

I am unable to take proper pictures of the projector in action, everything i take with it is way to dim to make out most of the projected image

Nearing the completion of the project i had an accident: i dropped a screw while reassembling the projector which just had to hit a 400v 150uf capacitor which discharged onto the control interface cable and destroyed it... The projector survived, could turn on and off and would display fine through vga but i could not change any settings or inputs making the projector quite useless.

I guess its off ward to the next one, an eiko EIP-2500 DLP projector... i plan on taking the led system from the now failed mod and installing it into the dlp projector