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Merlin #1 04/01/2008 - 01h39

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Hello all,
I'm from Australia and am wondering if there are other Aussies on this forum who can help me out with finding suppliers for quality parts (IR LEDs etc.).
From what I've read so far, my Logitech Communicate STX will not serve as my best receiver given I can't open it up at all (no entry point) and see if there is an IR filter in there, I presume there is but I don't know for sure.

While testing some Dick Smith IR LEDS (Z3235) last night I found reasonable results until I put the 3.5" disk media over the camera lens and found it cut out the IR completely.  :(

So I'm left wondering, will I have to import some IR LEDs?
(like Viper3two's suggestion of OSRAM SFH485P 5mm Flat top-wide beam angle 880nm wavelength LEDs from digikey.com)

And where can I get a cheap VX-1000 or similar (seen them advertised for $AU40 ish) webcam that I can actually get into and modify as required?

Thanks for any info.
Kestrel #2 04/01/2008 - 02h13

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Merlin @ 04/01/2008 - 02h39 a dit:

Hello all,
I'm from Australia and am wondering if there are other Aussies on this forum



G'Day Merlin!  :)

While testing some Dick Smith IR LEDS (Z3235) last night I found reasonable results until I put the 3.5" disk media over the camera lens and found it cut out the IR completely.  :(



I've used Dick Z3235 IR LEDs with a floppy filter without problems. Are you sure you're powering them correctly?

So I'm left wondering, will I have to import some IR LEDs?
(like Viper3two's suggestion of OSRAM SFH485P 5mm Flat top-wide beam angle 880nm wavelength LEDs from digikey.com)



You can get them locally from RS Components Australia here.
Merlin #3 04/01/2008 - 02h57

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Am I sure I powered them correctly?
Well, no. I wont get into the details but I only had two hooked up in series with 3V source and 1/4W 15ohm R.
My batteries may have been run down I guess?
Or, there is an IR filter in my camera which I can't access.

You say you have USED Z3235's before, so what are you using now??? :)

My initial tests had directional issues, 30-40' off center and signal would fade giving FT2.01 artifact light source points (multiple + signs). So that's why I thought I need a broader spectrum/beam angle...

I've emailed Logitech to ask if my camera has an IR filter because there is no mention of it in their documentation or on the box. But would this make the difference between being able to see the Z3235's Without 3.5" disk filter, then not being able to see them With the disk filter?

Thanks heaps for the link to RS Components. What would you recommend I do from here?
1) Obtain a modifiable webcam.
2) Obtain the broader beam angle IR LEDs
3) 1 & 2??

Thanks again for you help.
Kestrel #4 04/01/2008 - 03h57

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Merlin @ 04/01/2008 - 03h57 a dit:

You say you have USED Z3235's before, so what are you using now??? :)



I still use them, along with SFH485P, they're both just as good with the Z3235s sanded flat.

My initial tests had directional issues, 30-40' off center and signal would fade giving FT2.01 artifact light source points (multiple + signs). So that's why I thought I need a broader spectrum/beam angle...



The Z3235s need to be sanded flat to improve the viewing angle. To eliminate LED artifacts, make sure that only the front face of the LED is visible, you can ensure this by wrapping some black electrical tape or heatshrink around the LED base.

I've emailed Logitech to ask if my camera has an IR filter because there is no mention of it in their documentation or on the box.



All digital cameras have infrared filters.

But would this make the difference between being able to see the Z3235's Without 3.5" disk filter, then not being able to see them With the disk filter?



Yes. Use developed, exposed photographic film negatives instead of the floppy disk media, it's weaker so you don't have to remove your webcam's infrared filter.
Merlin #5 04/01/2008 - 04h33

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I'll give that a crack...
Thank you so much.
Merlin #6 04/01/2008 - 12h52

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Hope this still qualifies as General Discussion.....
I just sanded one LED down to see the difference against one that wasn't sanded down. It seems to be a compromise giving up intensity for better angular tracking.
The dome top of the LED must have some magnification properties which make it at least five times bigger when directly in font of the cam, I guess I'd just need to fine tune the camera settings to make sure it's able to track the reduced intensity LED.

I have yet to try some negative film but assume the intensity of the filed down LED won't be enough to cut through it.

About the camera (Logitech Communicate STX), I wouldn't recommend one of these for FreeTrack at the moment, given you can't open it to get at the IR filter. Most examples I've seen on here have made the Cam dedicated for Freetrack use, and I think that is what I'll end up getting (cheapycam) and keeping this one for it's original intended use.
Kestrel #7 05/01/2008 - 03h34

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Merlin @ 04/01/2008 - 13h52 a dit:


I just sanded one LED down to see the difference against one that wasn't sanded down. It seems to be a compromise giving up intensity for better angular tracking.



You'll find it's about the same as a SFH485P, focused LEDs are too bright anyway.

I have yet to try some negative film but assume the intensity of the filed down LED won't be enough to cut through it.



Negative film is a visible light filter so shouldn't significantly affect the LED infrared light.
Merlin #8 05/01/2008 - 05h39

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I got an AU$35 VX-1000 today, set it up like Viper3two's little tutorial vid.
I didn't factor in the scalabilty of the Threshold slider in FT2.01.
WOW, huge difference once I slid that down to the left, now I'm satisfied tracking will not be a problem at a sustainable frame rate.  :D

Next phase is design & construction of a self-powered 3-point Clip.
I was thinking of perhaps using 2x3V Lithium Button type batteries for weight and asthetic needs, however I need to work out how to mount them so they are easily replaced and don't interfere with the construct of the 3-point frame.
Ultimately I'd like the unit to be wireless and insert a small switch to turn on and off. Am I dreaming? :rolleyes:

Can you suggest any good threads around here for materials used on 3-point clips?
Kestrel #9 05/01/2008 - 06h51

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Lithium button batteries don't have a very long battery life:

CR2016: ~90mAh of charge so will provide 30mA of current for 3 hours.

Compared with:

AA: ~2500mAh of charge so will provide 30mA of current for 83 hours.

30mA is the bare minimum current you could use for IR LEDs with a modded webcam.

For construction ideas check out:

http://www.free-track.net/english/hardware/point_model_gallery.php
Merlin #10 08/01/2008 - 11h22

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This may be a stupid question ..... but.....
What is the life expectancy of an IR LED?
Obviously it will depend on how much it's used but is there a ballpark number of hours to expect out of a LED?
I'm asking because I don't know whether to construct plugs for the LED's or just hardwire them, if I had to replace a LED every 100 hours or so I'd probably opt to make a simple plug setup to make replacement quick and easy.
didja #11 08/01/2008 - 16h43

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On the web, I could find some numbers like 50 000 or 100 000 hours... Then I think you don't have to be anxious about the life expectancy... :)

Have a good day !

Rémy
Posted Image
Merlin #12 09/01/2008 - 02h35

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Ahh,,,, Hardwire it is then...
Thanks Didja.
ZefleR #13 11/02/2008 - 03h40

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Hi Guys,

I too am using the dick smith Z3235 leds. i think i paid about 3 bucks for the leds and resistors. I am powering my 3 point cap from my computer USB port.
My camera is a Logitech Quickcam 4000 which tracks ok. I have opened the camera up and removed the internal IR filter and replaced it with a piece of floppy disk. The camera picked up the leds fine but viewing angle was very small. this was solved by filing the IR leds down flat. I still get quite a bit of jitter and i think this is due to two reasons.
1. the settings on the quickcam are very useless and don't seam to make much difference to the exposure.
2. i havent tried this yet but i think i need to cover around the sides of my ir leads to eliminate LED artifacts. I will try this and let you know.

If anyne has a quickcam can you tell me your settings you have set. Cheers
Merlin #14 11/02/2008 - 05h51

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Hi Zefler,

the settings on the quickcam are very useless and don't seam to make much difference to the exposure.


I have a Logitech camera as well (not the QC4000) and I had dramas with the drivers and software when I bought it - ie. it wouldnt save my changes to settings when I exited so I'd have to redo everything every time I used it. I found better drivers/software by going directly to the Logitech website and looking for updates - this solved my software issues.

I think i need to cover around the sides of my ir leads to eliminate LED artifacts..


Yes this will help and is recommended, but also try adjusting the THRESHOLD slider if artifacts are a problem.

Here are a couple of pics of my Headphone mounted 3-point clip - It looks a little unfinished because I ran out of Heat shrink tube and didn't have any black insulation tape, but it works like a charm. This version powered by regulated 6V power adapter.

Posted Image
Posted Image

Good Luck.
p.s. pics are links to source if they don't show here :-(
Edited by Merlin on 11/02/2008 at 05h56.
ZefleR #15 11/02/2008 - 06h57

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Merlin thats very helpful. I'll try it out tonight and post results tomorrow. Thanks

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