> Final build, advise needed
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vyyye |
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Class : Apprenti
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Registered on : 02/04/2013
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Hey,
Found out about this a few days ago and decided to build it. I'll use a reflection setup.
Essentially going to stick my diodes around the webcam, the number (10) I presume should be enough as 8+ was recommended.
Thinking of powering them with
http://www.kjell.com/sortiment/el/stromforsorjning/nataggregat/ac-dc/stallbar-utspanning/stallbar-natadapter-3-12-volt-p44264
These are the diodes in question, wavelength is 950nm, not quite like the recommended one but these are available without paying 10x the price in shipping:
http://www.kjell.com/sortiment/el/elektronik/optokomponenter/ir-dioder-fototransistorer/ir-dioder-5-mm-10-pack-p89281
And adding a 10 Ohm resistor for every diode (thinking I'll connect them parallel).
Anything you would change here? |
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Stormrider |
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Class : Légende du Forum
Posts : 466
Registered on : 02/01/2013
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Hi vyyye,
I think 10 ohm resistor is not enough.
You want to connect the leds all paralel with their own resistor of 10 ohm.This means that if you put your powersource at 3 Volt for each line(led+resistor)
led:1volt- 20mA
powersource: 3Volts
(3v-1v)/10ohm=0,2A(=200mA)
200mA is a bit to much,so I think you need a 100 ohm resistor instead of a 10 ohm.
(3v-1v)/100 ohm=0,02mA (=20mA)
If I wanted to make your setup I would choose to connect all the leds in serie with just one resistor with the powersource at 12Volts.
(12V-10V)/20mA= 100 ohm
The dissipated power in the resistor will be:
P=I X I x R
0.02x0.02x100=0.04Watt
If you decide to connect them all serial, you don't need so heavy nätadapter.
This one will be sufficiant and is cheaper.
http://www.kjell.com/sortiment/el/stromforsorjning/nataggregat/ac-dc/stallbar-utspanning/stallbar-natadapter-3-12-volt-p44108
This one provides 300mA and you need 20mA.So that should be enough.
Iam not an expert with ir-leds and electronics, but if that 20mA is the max current for the led.Maybe you can first try your setup with a bit higher resistor(130 ohm?).Just to be on the save side.
I hope this helps you a little.
greetz Stormrider |
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vyyye |
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Class : Apprenti
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Registered on : 02/04/2013
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Hey Stormrider,
Thanks a lot, sorted on the info front now. Just need to get down to building.
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Steph |
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Class : Moderator
Posts : 656
Registered on : 16/11/2007
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Hi,
I'm not sure, but it seems that they have change the voltage and current values on the website from yesterday to today. The LEDs are know given for 1,35V forward voltage and 100mA max. current, which makes more sense when comparing to the LD271.
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Stormrider |
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Class : Légende du Forum
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Hi,
yes Steph you are right.They changes the specs of the leds on the site.
I hope they changed it on the site before vyyye ordered, because with this new info he need an other netadapter and
an other type of building his setup.
greets Stormrider
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vyyye |
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Class : Apprenti
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Registered on : 02/04/2013
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Edit: Solved, diodes connected the wrong way (or at least one was). Thanks anyway people, got my Freetrack working, just some tweaking left! Possibly some floppy magnetic stuff to put in front of camera lens, light inteferes a bit.
Edit2: Or so I thought, seems I was only catching reflections coming from my monitor which is odd. I have 1V over each diode (with 3V from the power source). Reflections on my headphones is stronger than reflection from diodes + headphones.
Really confusing, the circuit is definitely whole yet the diodes are just.. not doing anything.
Edit3: And NOW it's working. Just needed to up the voltage, but boy does the resistor get hot. Time to tune, ah, finally. Only problem is my headphones reflecting a bit too much but that's easy to fix.
Edited by vyyye on 04/04/2013 at 22h02. |
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Stormrider |
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Class : Légende du Forum
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did you remove the ir filter of your webcam?If the resistor is getting so hot, I think to much current is flowing throug your setup.What voltage do you use?
greetz Stormrider
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vyyye |
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Class : Apprenti
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Stormrider @ 04/04/2013 - 23h57 a dit: did you remove the ir filter of your webcam?If the resistor is getting so hot, I think to much current is flowing throug your setup.What voltage do you use?
greetz Stormrider
Unable to remove the IR filter, have a "bad" PS3 Eye (and already destroyed one!). And yeah put the voltage down a bit which drastically reduced temperature. Now when I've tried to calibrate it I see I have issues with the actual setup, ordered the SFH485P to see if they will help to overcome the IR filter.
Edited by vyyye on 05/04/2013 at 06h56. |
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Stormrider |
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Class : Légende du Forum
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Hi vyyye,
did you read this post?
http://forum.free-track.net/index.php?showtopic=3562
on youtube,
http://v.youku.com/v_show/id_XNDkwNTQ4NDg4.html
maybe it can work for you to.On youtube it looks working alright.
greetz Stormrider |
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vyyye |
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Class : Apprenti
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Stormrider @ 05/04/2013 - 18h25 a dit: Hi vyyye,
did you read this post?
http://forum.free-track.net/index.php?showtopic=3562
on youtube,
http://v.youku.com/v_show/id_XNDkwNTQ4NDg4.html
maybe it can work for you to.On youtube it looks working alright.
greetz Stormrider
Hi, no not seen that particular post but read some post(s?) saying they got it to work with regular lights. That video is more than proof enough that it seems to work.
Going to try with the IR lights from the recommended IR diodes in the sticky first though. I mainly see two advantages, one being that it won't bother me in night missions (regular lights would reflect against my monitor) and the other that it could work even if I have my room light on. If that fails as well though? Visible lights all the way.
Diodes will arrive next week but have one question, would 6 Ohm work for the serial circuit in the sticky? As I can regulate my voltage I thought of just reducing the voltage a bit (3 or 4, not done the maths yet). As far as I can see I should easily be able to offset the .8 difference, though I haven't really made 100% correct judgements all along this little project..
Problem is I only have access to 18Ohm resistors so going to have three in parallell, else I could get 9Ohm (two in parallell) but I really want as much IR as possible.
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Stormrider |
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Class : Légende du Forum
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Hi vyyye,
lets say you want to use 80mA for you ir-leds(sfh485p) and you have a 18ohm resistor.
Voltage= I(current) x R(resistor)
0.08 X 18=1,44 V
Those sfh485p have a voltage drop of 1.5v each.You powersource must provide 1.44V+ 4.5(from the leds)= 5,94V.If you put your powersource at 6 volt you will have 83mA running trough
your setup with 125mWatt for your resistor(power dispensation)
You just need one resistor of 18ohm and your powersource at 6volt.
greetz Stormrider
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vyyye |
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Class : Apprenti
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Stormrider @ 06/04/2013 - 16h18 a dit: Hi vyyye,
lets say you want to use 80mA for you ir-leds(sfh485p) and you have a 18ohm resistor.
Voltage= I(current) x R(resistor)
0.08 X 18=1,44 V
Those sfh485p have a voltage drop of 1.5v each.You powersource must provide 1.44V+ 4.5(from the leds)= 5,94V.If you put your powersource at 6 volt you will have 83mA running trough
your setup with 125mWatt for your resistor(power dispensation)
You just need one resistor of 18ohm and your powersource at 6volt.
greetz Stormrider
Hey Stormrider,
6V it is, thanks for clearing that up. Somehow managed to confuse U=IR despite everything, oh well.
Just a final question before I get down to building the cap (assuming LEDs arrive soon), do I just place the negative film in the sun to make it "exposed"? How long do I leave it and do I need to do it at both sides?
Cheers
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Stormrider |
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Class : Légende du Forum
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Hi vyyye,
I don't have any experience with negative film, I use a floppy-disk as a filter.So I can't help with that, maybe you can use google to find info about it.
greetz Stormrider
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dewey1 |
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Class : Habitué
Posts : 191
Registered on : 25/06/2010
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You realize it is developed film that has been exposed to sunlight for the light filter you must use don't you? Basically the developed negative which is black.
Unexposed developed film negative is clear.
It is usually cheaper to ask for a piece of developed film, the end piece from a film developer store.
You can also use the reddish/black plastic off of an old VCR or any other IR remote device. (Transmitter or the receiver) This plastic is an IR pass filter which blocks any thing outside of the IR spectrum.
I just used a piece of floppy disc media.
http://www.discovercircuits.com/H-Corner/color-neg.htm
Edited by dewey1 on 06/04/2013 at 22h37. |
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vyyye |
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Class : Apprenti
Posts : 7
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dewey1 @ 06/04/2013 - 21h56 a dit: You realize it is developed film that has been exposed to sunlight for the light filter you must use don't you? Basically the developed negative which is black.
Unexposed developed film negative is clear.
It is usually cheaper to ask for a piece of developed film, the end piece from a film developer store.
You can also use the reddish/black plastic off of an old VCR or any other IR remote device. (Transmitter or the receiver) This plastic is an IR pass filter which blocks any thing outside of the IR spectrum.
I just used a piece of floppy disc media.
http://www.discovercircuits.com/H-Corner/color-neg.htm
I now realize that, oops. Got floppies on the way to use that instead, unfortunately don't have many remotes I can dissassemble.
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