FreeTrack Forum

Hello everyone,

I'm nub in electronic and totally new to FreeTrack.
I mount 3 IRleds Headset but when I power on, it seems the led do not work.
So I am not sure the Resistor I put is the one I need, I of course use the Led Assembly wizard to calculate this resistor and to check if I could make a Serie o Paralel.

So the Power Supply is a Mobil Phone  AC-AC that I found with  output 9v 800ma
The 3 leds are from TV control remote blue color glass should be standard IRled 1.3 v and 20mA to 100mA.
Resistor 390 Ohms , 1/2 watt.
I am sure the Led are correctly connect Positif to Anod and as Wizard indicated mount in Serie

So in the Wizard I put as mA 20, and it suggest the 390 Ohms resistor which I installed. But even in a completly Dark room the led do not show anything. (I do ot have yet a Web Cam to check if this one could detect the IRled signal, but I suppose in completly dark room it should show some red point).

It that because my Resistor is putting to low the mA. Should that put in Wizard Led 75 mA (which will suggest a 100 Ohms resistor) instead of 20mA?

Thank you for the great Idea of economic Head Tracking and also thank you in advance for your help on this matter.

Hello Paxesalute , and welcome aboard.

I do not have yet a Web Cam to check if this one could detect the IRled signal, but I suppose in completly dark room it should show some red point

No.
Only some IR leds emit a kind of visible light.

To make things simple, IR isn't a color but a range of color.
There are "colors" of IR.... (ouch , but it's an easy way to say it)  

We'll just consider 2 of these "colors" :
880nm and 940nm

880nm is very close to red light (its near the border of the IR range) , so 880nm IR color will be barely visible to human eye (IE : SFH485, which  are 880nm IR leds, emit a very very dim red light when operating).

940nm is more inside the IR range, and really outside human eye capabilities.
So 940nm is invisible to human eye.  


Since you salvaged your leds from TV remote controls, you can't guarantee the led model, nor the IR "color".

So your setup can be ok, even if you don't see any light coming from your leds (using your eyes). You'll have to check with a webcam.

Resistor 390 Ohms , 1/2 watt.

Value ok , for the given settings.  

It that because my Resistor is putting to low the mA. Should that put in Wizard Led 75 mA (which will suggest a 100 Ohms resistor) instead of 20mA?

Normally , it shouldn't be the case.

But operating your leds at 20ma is ok if your webcam is IR modded, but will probably be a value too low for an unmodded webcam

(you'll have to test it once you have your webcam)

If you know somebody owning a WII, you can check your leds using his wiimote, since the wiimote has a builtin IR tracking webcam.

Tell us the results of your tests  

cya

Another way to test whether your IR is operating or not, is to use a digital camera or a camera mobile. Just direct the camera towards your IR and look in the camera display. You will immediately see if the LEDS are operating or not.
Good luck!

Not necessarely.

I already had problems to take shots of a previous working setup with a digital camera, because i was using 940nm leds and the camera builtin IR filter was a bit strong.

I finally had to take the shots using my IR modded webcam.


So, it's a false assumption to think every digital camera or webcam WILL see every Ir led.

Some cameras will see some leds.

If you're lucky, it'll work.
But if your camera doesn't see the leds , that doesn't mean the leds aren't working !!!!



By using the wiimote to check your setup , you're on the safe side since its webcam is designed to track IR leds.

cya