Project Nova Luxy

[rhd]

I spilled the beans a bit on this project over at PL, so I figured I would share my progress here as well. I've chatted casually with a few people on LPF about this project, but I thought I would share it openly now.

Project Nova Luxy (Latin for "New Light") is my attempt to bring life back to barren DLP projectors, by creating a workable LED-based replacement for missing LDs.

Surprisingly, I've actually had to invest a fair amount getting to this stage in my experimentation between various LED emitters I've tried, lens options, prototype PCBs, components from digikey, etc. I had hoped to recoup a bit by selling some sort of kit for DIY hobbiests to birth life back into their unused projectors. Of course, that's not quite in cards, since the project doesn't work
(at least not yet)

But I've made a decent amount of progress, and success may still be in the cards.

I've managed to completely lick the electronics. Replacing the LDs with high enough power LED emitters is (I believe) solved. Heat issues are (again, I believe) solved. Tricking the projector into thinking that each of the 4 LED emitter plates is a functional string of 6 LDs, again solved.

At this stage, what is not solved, is collimating the LED output into a focused enough output of light to create any meaningful BLUE/GREEN output. In my prototypes, I can successfully run the projectors with RED only output, and even with the BLUE emitter LEDs fully powered up, for an unlimited period of time. It's stable, you could watch a movie in RED etc.

Here's a quick demo video.
Project Nova Luxy - YouTube


It is what it is. Someone may have a brilliant LED collimation idea that will unlock the last hurdle. I can tell you that I've tried upwards of 20 lens options from surplus shed, and the best so far is to use a very short focal length coated glass lens on each LED emitter plate. That's what you see on each emitter in the video above. However, as mentioned, this isn't enough, and there nearly no actual BLUE/GREEN light in the projected output when the heatsink/LED assembly is running inside the projector.

 

[532 with Envy]

Nice job working the electronics and fooling your projector into working again! That a fun experiment....if you can get the blue working completely and focused you could almost resell them as working projectors

 

[Benm]

I guess you should change the project name though... "new light" would translate into "nova lux", and "new lights" into "nova lucis".

Replacing the LD's by another lightsource will probably prove difficult, they didnt opt for a source this expensive in the first place. Perhaps you'd get better results running on a reduced number of LD's. Removing half of them would tilt the color balance a bit, but probably not yielding an unusable projector.

 

[rhd]

I guess you should change the project name though... "new light" would translate into "nova lux", and "new lights" into "nova lucis".

Replacing the LD's by another lightsource will probably prove difficult, they didnt opt for a source this expensive in the first place. Perhaps you'd get better results running on a reduced number of LD's. Removing half of them would tilt the color balance a bit, but probably not yielding an unusable projector.

I added the "y" because it sounded cooler

Actually, you can run these projectors with half of the LD's removed. In fact, you can get a fairly usable output. They've done that over at PL a bunch.

The challenge is, there are a ton of projectors around that have zero LDs in them, and it would be nice to see those not go to waste.

That said, I agree in principal that they would have gone LED in the first place, if it was really that easy.

 

[Benm]

I suppose there could be some use for the projectors with the LD's removed. Perhaps it is possible to change the red led for a white one with a similar output pattern, making the projector black and white.

 

[bobhaha]

The problem is that you can not make a good green and blue at the same time, right?

What if you used some high powered UV LED's? At the same time as the blues. UV is what makes the phosphor glow the green colour.

Just a thought

 

[rhd]

I suppose there could be some use for the projectors with the LD's removed. Perhaps it is possible to change the red led for a white one with a similar output pattern, making the projector black and white.

This is a fantastic idea. I'm going to try my bypass circuitry, with the Phlatlight replaced with a similar WHITE LED. In theory, there will be 1/3rd the refresh rate. But I think that might actually be resolved by placing a beefy cap in parallel with the phlatlight (to smooth the pulsing, and cause the red to be powered up during all of the R, G, and B DLP cycles.

The problem is that you can not make a good green and blue at the same time, right?

What if you used some high powered UV LED's? At the same time as the blues. UV is what makes the phosphor glow the green colour.

Just a thought

The issue with that is that high power UV LEDs are insanely expensive. Plus, even the BLUE is still problematic. It's still an issue of focus, not quantity of light output.

 

[foulmist]

ooooh goooooooooodie ...B & W would be awesome if it works alright...

it will give a retro touch to the projector which to me sounds pretty good...

.....
I kinda loved the b&w crt monitors back in the days I had one which I liked more then the vga

great project there RHD :beer:

 

[rhd]

The CST-90 will work, thermistor compatible and all.

EDIT: It's not cheap though. $50 +

 

[Benm]

Perhaps it would be possible to modify the circuitry so the white led is always powered on, or at least during the time that normally has the green and blue cycle. This would give less ficker, but also the advantage that an RGB input signal would be rendered as decent black and white. It wouldn't have color weiging, but at least portions that are green, blue or cyan would be rendered to some degree.

As for the price: $50 + some circuitry would not be that bad to convert a mostly useless red-only projector shell into a functional b/w projector. It could be a 'fun' retro project, but also perfectly functional for displaying informational text in public spaces and such.

 

[rhd]

Perhaps it would be possible to modify the circuitry so the white led is always powered on, or at least during the time that normally has the green and blue cycle. This would give less ficker, but also the advantage that an RGB input signal would be rendered as decent black and white. It wouldn't have color weiging, but at least portions that are green, blue or cyan would be rendered to some degree.

As for the price: $50 + some circuitry would not be that bad to convert a mostly useless red-only projector shell into a functional b/w projector. It could be a 'fun' retro project, but also perfectly functional for displaying informational text in public spaces and such.

EXACTLY. Taking only the red channel will not produce a true black and white image (well, it will, but it won't look like "normal" black and white)

I was thinking that a capacitor would be enough to smooth out the pulse on that LED. Think that would work? Something like this:
Digi-Key - 445-4827-ND (Manufacturer - FK11Y5V0J107Z)
Across the LED leads in parallel?

 

[Benm]

I doubt it. I guess the projector cycles through all the colors 24/25 times a second, giving you a grap of about 80 mS to fill between cycles. You can use a bunch of those caps to store the required amount of energy, but that would require a driver to keep a constant current flow.

I'm not really sure how the current source of the projector is wired though. It may be possible to route the power source for the lasers to the led too using diodes.

As for mixing colors to blank and white: If you do it properly, the colors are weighed (in the order of 60% green, 30% red and 10% blue) before adding them up. Just blindly adding them in a 1:1:1 ratio (what would happen if you put in a white led and ran it for all the color cycles) will result in a bit of an odd picture, but its still usable.

Its probably possible to correct for this error at the source (i.e. the computer driving the projector) so it wouldn't worry about it much.

 

[rhd]

If you ran white for all the colour cycles, I think you'd still be mixing the images meant for each colour in a 60/30/10 (or whatever was intended) ratio. The DLP chip cycles the image, it's not just the pulsing of the actual light sources. So the DLP chip will hold on to the image intended for green, for 60% of the time, etc etc etc.

 

[Benm]

I'm not sure how the DLP is driven. It could do cycles of equal lenghts for every color, with the white balance simply resulting from the brighness of each color light source in the original projector.