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FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > 1 Point model

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freelancer27 #1 23/01/2008 - 16h41

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Guys I've been working on this for some time and have yet to get it to work. I've been trying a 1 point model (Pitch and Yaw) with two seperate constructions made with no results.

I was using an IR Diode of the type rcomended,  1.5V 100ma and was using a 9V battery and 100ohm resistor.

Rmoved the IR filter from my Microsoft VX3000 and placed a piece of floppy disc on the exposure. In testing the cam I unchecked the auto exposure on the Free-track software and I tested the cam with a regular TV remore control and got a nice big red dot.... so cam looks good.

When I connected my battery to my diode/resistor I get nothing. I get more output from my hand than I do my diode.

At this point I'm willling to try anything. Maybe 9V was too much voltage, but with the 100ohm resistor I thought it would be ok.

I need feedback from someone that has built a single diode system. I'm willing to try different power supply voltages etc.  I have 1 IR diode left and I'd like to get some input from someone that has had success with this 1 point model with known good power supply/ resistor values.

Thanks for your help,

Frustrated.
zundap #2 23/01/2008 - 19h10

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hmm with 9v with a 100ohm resistor you should get about 80mA on the led ( might be too much ) 70mA is the recomended maximum for those leds if they are not mounted on a PCB.

Try to change the resistor to 150ohm.

oh and check the polarity of the led!!!! if you connect it wrong it wont work :P
zaelu #3 23/01/2008 - 21h14

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When I builded my first setup I run in to some similar problem and I discovered that my IR diode was not a LED (light emiting diode) but a recieving one  :D  :D  :D  ... You know... the TV set has a similar diode for revcieving the light from your remote... if you have a recieving one... you get squat.

Also... I use LEDs with 1.2v 20mA... for usual IR LEDs I heard this are the values. 100mA could be overestimated and a 100Ohms resistor with a 9V battery could ensure the burning of your LED (I burned one and is pretty funny :) )
Edited by zaelu on 23/01/2008 at 21h16.
freelancer27 #4 23/01/2008 - 23h40

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Thanks for the replies. I'll take a look at the polarity again but I thought I was pretty carfull to go red wire (hot) to long, pointy ; )  lead, but you never know.

100 ohm resistor should have given me 60ma which is quite a bit below the 100 ma limit.

If a diode does blow, is it visible. That is can I tell by looking at it that it has been over loaded? I took a look at it earlier and it looked ok.

I think i'm going to change out my power supply and resistor and try again with lower voltage.

Thanks again for your help.
Edited by freelancer27 on 23/01/2008 at 23h40.
Kestrel #5 24/01/2008 - 00h34

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freelancer27 @ 24/01/2008 - 00h40 a dit:

Thanks for the replies. I'll take a look at the polarity again but I thought I was pretty carfull to go red wire (hot) to long, pointy ; )  lead, but you never know.



Sounds like you got the polarity wrong, ignore the lead lengths in the case of SFH485P (they're opposite convention) instead use the flat side of the LED as an indication of the negative side.


If a diode does blow, is it visible. That is can I tell by looking at it that it has been over loaded? I took a look at it earlier and it looked ok.



I don't think damage is visible for the small amount of power used in a typical LED powering circuit. Put a few amps through it though and you would probably see some damage... :p
 

 
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freelancer27 #6 24/01/2008 - 14h49

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Sounds like you got the polarity wrong, ignore the lead lengths in the case of SFH485P (they're opposite convention) instead use the flat side of the LED as an indication of the negative side.



You were absolutley correct!  Rigged up another diode/pwr supply and reversed the polarity and viola! Getting a steady 27 frames with about 25 jitter (I'll have to read and see how I can reduce the jitter.

Opened Falcon4 AF and it was responding great. Now I'll go ahead and solder it together and put it in a cap.

Kestrel thank you so much for your help. This is going to greatly increase my game play.

Thanks again!

[b]EDIT[b]  On the model I made that uses a 9V battery..... The battery is getting quite warm. Is this something to be concerned about?
Edited by freelancer27 on 24/01/2008 at 17h41.

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