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Posted: 04 May 2009 07:46 AM   [ Ignore ]   [ # 61 ]
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Have you checked that all of your LEDs are working and emitting light?

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Posted: 04 May 2009 07:51 AM   [ Ignore ]   [ # 62 ]
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Ancalagon - 04 May 2009 07:46 AM

Have you checked that all of your LEDs are working and emitting light?

Meanwhile 2 groups of 7 LEDs aren’t working at the moment. I will fix them as the day progresses.
But since they’re wired in parallel, that shouldn’t be a (the) problem.

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Posted: 04 May 2009 01:02 PM   [ Ignore ]   [ # 63 ]
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Wow, meanwhile 4 groups aren’t functionating.
I got the devil inside my project…
Some LEDs seem to not work anymore - don’t know why.
I got to reorder some new LEDs at conrad.de.

But that still doesn’t solve the main problem in my opinion.

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Posted: 04 May 2009 01:23 PM   [ Ignore ]   [ # 64 ]
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Have you measured the temperature of your LEDs? You’ve got them insulated quite good by the thick MDF plates, maybe your casing doesn’t dissipate the 50W of heat so your LEDs are overheating.

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Posted: 04 May 2009 01:32 PM   [ Ignore ]   [ # 65 ]
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No I didn’t measure the temperature, but I tested them the last days mostly without the lid, so the heat could rise.

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Posted: 04 May 2009 02:52 PM   [ Ignore ]   [ # 66 ]
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I think you should find out why your LEDs aren’t drawing the calculated 4.2 A current and why they are failing. I guess there are lots of people at your university who have a deeper understanding of electric circuits.

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Posted: 05 May 2009 02:17 AM   [ Ignore ]   [ # 67 ]
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How can you be sure that the leds themselves aren’t the problem? if entire groups of leds fail, then there might be a power supply problem, heat or anything related to the light which might be the culprit at the time of testing. I mean, in your picture you see no blobs at all, and if even one series of leds work, then there should be faint light from any side bouncing of your fingertips…

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Posted: 05 May 2009 04:08 PM   [ Ignore ]   [ # 68 ]
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Ancalagon - 04 May 2009 02:52 PM

I think you should find out why your LEDs aren’t drawing the calculated 4.2 A current and why they are failing. I guess there are lots of people at your university who have a deeper understanding of electric circuits.

I checked them today with a “Stromzange” and they’re drawing the 4.2 A.
Okay, meanwhile only round about 3.9 A, but 4x7 LEDs aren’t working at the moment, so the value fits.

Mday - 05 May 2009 02:17 AM

I mean, in your picture you see no blobs at all, and if even one series of leds work, then there should be faint light from any side bouncing of your fingertips…

I don’t understand your last sentence, sorry. As I said, the LEDs are working well (except the 4 groups I mentioned above).
I’m not 100% sure, that the problem proceeds from the LEDs.

------------------------------------------------------------

I got some updates and facts. Maybe someone spots a cause for my problem:

- Today I tested my setup with a piece of half-transparent baking paper above the EndLighten, but got no results.
- The LEDs draw their 4.2 A as mentioned above.
- The edges of the EndLighten have gotten polished a while ago by a professional plastics-speccialist.
- The LEDs are sitting relatively tight on the EndLighten with a angle of 90° to the edges of the EndLighten, therefore horizontally and parallel to the EndLighten itself.
- The table has been tested in a light and a dark environment.
- The EndLighten was tested on both sides.
- Cam is a Sony PS3Eye with removed IR-filter, but the lens has been replaced anyway. I’m using a wide angle lens now and a “NIR Optical Filter, 880DF20, 11.5mm painted edge” which fits to the 880 nm of my Osram SFH-485P. As far as I understand, the filter should block ALL light with less than 860 nm and more than 900 nm, right? That’s what the 20 stands for (+/- 20 nm).
- When the 7D006 is laying on the EndLighten and I’m poting my TV-remote on both layers, the cam recognizes the IR-light of the remote and creates a blob. Strangely this also works with a torch and a lighter. Shouldn’t these lights get blocked by the filter?
- The internal PC is also powered by the same PSU which powers the LEDs and the fans.
- The mirror is NOT a first surface mirror, but I don’t think, that this fact leads to my problem or am I wrong?
- I’m using NO hot mirror in front of the projector. Could this be a cause for my problem?

I hope these additional facts can help to find a solution, because I don’t want to give up my time- and money-consuming DIY-LED-solution to replace it with LED-strips which would cost another 250 Euro including shipping :(

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Posted: 05 May 2009 04:37 PM   [ Ignore ]   [ # 69 ]
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cdog - 05 May 2009 04:08 PM

- Cam is a Sony PS3Eye with removed IR-filter, but the lens has been replaced anyway. I’m using a wide angle lens now and a “NIR Optical Filter, 880DF20, 11.5mm painted edge” which fits to the 880 nm of my Osram SFH-485P. As far as I understand, the filter should block ALL light with less than 860 nm and more than 900 nm, right? That’s what the 20 stands for (+/- 20 nm).

Bandpass filters are usually interference filters. This may cause problems with your wide angle lens. Try replacing the bandpass filter with one or two layers of exposed photo negative.

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Posted: 05 May 2009 04:51 PM   [ Ignore ]   [ # 70 ]
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Will a piece of floppy disc also work?
And should I also put the original lens back on?

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Posted: 05 May 2009 05:17 PM   [ Ignore ]   [ # 71 ]
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cdog - 05 May 2009 04:51 PM

Will a piece of floppy disc also work?
And should I also put the original lens back on?

I have heard from some people that floppy discs may also work. The lens probably isn’t so important as long as it’s a lens without IR coating. You could also try it without an IR filter in a dark room. If you have no ambient light, you don’t have to filter it out.

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Posted: 05 May 2009 07:52 PM   [ Ignore ]   [ # 72 ]
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Okay, I switched back to the original lens - first test with 2 layers of floppy disc, second test with the 880DF20 filter.
Results are a bit better but still far away from getting good blobs :(

Something has to be completely wrong in my setup, but I can’t figure out, what it is.
It’s not that I’m getting weak blobs or something like that - I’m getting NO blobs with a additional layer on my EndLighten…

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Posted: 05 May 2009 08:03 PM   [ Ignore ]   [ # 73 ]
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Im sorry to say it again man, but it may be your LEDs.

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Posted: 06 May 2009 03:49 AM   [ Ignore ]   [ # 74 ]
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cdog - 05 May 2009 07:52 PM

Okay, I switched back to the original lens - first test with 2 layers of floppy disc, second test with the 880DF20 filter.
Results are a bit better but still far away from getting good blobs :(

Something has to be completely wrong in my setup, but I can’t figure out, what it is.
It’s not that I’m getting weak blobs or something like that - I’m getting NO blobs with a additional layer on my EndLighten…

The original lens has an IR blocking coating. You have to make sure that your lens doesn’t have such a coating.

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Posted: 06 May 2009 03:58 AM   [ Ignore ]   [ # 75 ]
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Ancalagon - 06 May 2009 03:49 AM

The original lens has an IR blocking coating. You have to make sure that your lens doesn’t have such a coating.

You mean the original IR-filter?
I removed it to insert the bandpass filter…

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