Trackir Building

[Pappy]

Apparantly Im the only pilot who doesnt have TrackIR at the moment . haha Trout talked to me about building my own and gave me a rough idea of how to do it. I did some research online and had some questions. I know perf and trout built there own together, so i know it can be done. lol

1: Using a USB cord as your power source only provides 5v of power. If you need 3 LEDs running at 3v per, how do you power them? Is it acceptable or even possible to use lower voltage LEDs?

2: relating to question 1, will i need a resistor if my 5v of power are not exact to what the LEDs use? ie: 5v USB powering 3 1v LEDs. (2 volts remaining) will that over power and blow the LEDs?

3: When wiring, Ive red the Red wire in USB is the hot (positive) and the Black is the neutral (ground) and the other shouldnt be needed. Is this accurate?

Im sure ill have more questions later. just doing to tech and research before starting.

Btw: I read the default IR LED (OSRAM SFH485P) take 3volts to power. Im assuming that is the standard. Right?

Thanks guys,

Pappy

[gec]

Apparantly Im the only pilot who doesnt have TrackIR at the moment . haha   Trout talked to me about building my own and gave me a rough idea of how to do it.  I did some research online and had some questions.  I know perf and trout built there own together, so i know it can be done.  lol

1: Using a USB cord as your power source only provides 5v of power.  If you need 3 LEDs running at 3v per, how do you power them?  Is it acceptable or even possible to use lower voltage LEDs?

2: relating to question 1, will i need a resistor if my 5v of power are not exact to what the LEDs use? ie: 5v USB powering 3 1v LEDs.  (2 volts remaining) will that over power and blow the LEDs?

3: When wiring, Ive red the Red wire in USB is the hot (positive) and the Black is the neutral (ground)  and the other shouldnt be needed.  Is this accurate?

Im sure ill have more questions later.   just doing to tech and research before starting.  

Btw: I read the default IR LED (OSRAM SFH485P) take 3volts to power.  Im assuming that is the standard. Right?

Thanks guys,

Pappy

1. OSRAM SFH485P takes 1.5V @ 100mA current so USB power is sufficient.

486602_DS.pdf

2. U need to have resistor not only to suppress Voltage then the current to. so a resistor is a must. Here is a good calculator for the purpose. SFH485P has 1.5V Forward voltage and 100mA Forward current.

3. that is correct

Gec

[Perfesser]

1: Using a USB cord as your power source only provides 5v of power. If you need 3 LEDs running at 3v per, how do you power them? Is it acceptable or even possible to use lower voltage LEDs?

In this case you would wire the LED's in parallel and use a resistor over each LED to drop the voltage to 3v.

2: relating to question 1, will i need a resistor if my 5v of power are not exact to what the LEDs use? ie: 5v USB powering 3 1v LEDs. (2 volts remaining) will that over power and blow the LEDs?

Mine just shut off when I applied an overvoltage but yeah you have to get the voltage right or you'll have troubles. The Freetrack website has a calculator.

You plug in the values of your LED's and get a wiring diagram with resistor specs and even a resistor picture chart.

3: When wiring, Ive red the Red wire in USB is the hot (positive) and the Black is the neutral (ground) and the other shouldn't be needed. Is this accurate?

Pin Name Cable color Description

1 VCC Red +5 VDC

2 D- White Data -

3 D+ Green Data +

4 GND Black Ground

Yup, red is pos, black neg and you don't need the other two. Probably best to isolate them, dunno what would happen if they shorted out.

And USE SHRINK TUBING, not electrical tape. These wires are too small for tape.

LED's are polarity sensitive, they have a pos and a neg. Wire them properly.

Btw: I read the default IR LED (OSRAM SFH485P) take 3volts to power. Im assuming that is the standard. Right?

I used a different one on the very bottom of this page

http://www.mainelectronics.com/KLInfraredEmitLED.htm

The important thing is the viewing angle, determines how far you can turn your head before your camera looses the signal.

160 deg should be enough. The OSRAM ones above will work fine but you have to wire in parallel as per the Freetrack website.

Parallel wiring has advantages - if one LED burns out you'll know right away because one won't work. Easy for anyone to troubleshoot.

If you use 1.5v LED's and wire in series with a resistor if any one component fails the whole thing will just stop without a clue if it's the power supply or an LED or the resistor or even the USB hub inside the computer.

Or (like Trout) a wire that overstressed and just broke.

A lot more steps to track down the problem.

Had a chat with Pappy last night on TS and gave him part numbers and some tips to get started.

Shopping list:

LED's

resistor(s)

thin solder

shrink tubing

Camera?

[Pappy]

Thanks for the help guys. I went shopping today and got most of the parts i needed. My local radioshack employees must be extra special because they overcharged for the webcam I got so I need to go back now. But they didnt have the resistor I was looking for. Theres ones more electronic store around here I need to check before just ordering it online.

Heres a list of my supplies:

1 pack of shrink tubing (will be using for insulation) 7$

3 IR LED emitter & receiver (they didnt have any of just IR emitters, o well extra parts for later projects) 9$

1 Logitec Quick Cam $24 (Charged me 40 those bastards!)

Total: 40$

essential tools needed also

1 hobby level basic soldering set : 8$

1 USB 2.0 Hub (Im outta ports! ) 22$

Not bad Id say. Only about a dollar for my resistor once I find it! Hopefully by this weekend it will be ready to test!

[Pappy]

Status update:

Went back to radioshack, got my 16$ back, haha. Then went to Fry's Electronics and found a adequate resistor. 4.7 Ohms 1/8 watt

My original design was to use the clothes hanger method on a ball cap. However when rummaging through my drawers I made a great find. The tip of a BIC ballpoint pen is exactly 5mm! A perfect fit to extend and hold my LEDs. So ive modified my design, emptied and cut 3 BIC pen casings and will be attaching them to my already uncomfortable headset. (probably with electrical tape.) Ive got my positive and ground wires measured and cut for the tubes, all I have to do is attache the LEDs, connect the wires (my first time soldering, If you guys dont hear from me after this weekend, call the fire department), throw in my resistor, and then attach it all to the headset. Thanks for all the help and ideas guys. Im actually having more fun researching and making this thing than i probably will using it! well.. maybe not... Im looking forward to tracking you all soon. Muwahahahaha

[gec]

how did u get the resistor value? it seems way to low to me. did u use the calculator i've put the link.?

i've entered the values for SFH485P and i got 20 ohms.

[Pappy]

how did u get the resistor value? it seems way to low to me. did u use the calculator i've put the link.?

i've entered the values for SFH485P and i got 20 ohms.

5mm IR Emitter

1.3v - 1.7v

150 ma

5V USB Power source

For a 1.5V, the calculator says 3.3 ohms, but i couldn't find one. For a 1.4 V it says use a 5.6. I found the happy medium of 4.7. Any ideas? I verified with the calculator.

[gec]

yep, u r right. i've entered wrong value for the Forward Voltage

my bad

[Pappy]

yep, u r right. i've entered wrong value for the Forward Voltage

my bad

Well, You may have been right.. According to the calc im using the right level.. But ive just finished putting it all together and the resistor is getting way too hot.. I was using a 4.7ohm Mayhem said with his 9v power supply he was using a 220 ohm resistor... Any ideas on a good safe resistor level?

I was so close to being done! lol I wanted to use it tonight

[Pappy]

Note: I just went to radio shack and got a 10 ohm 1/4 (was using 1/8) 5% I replaced the 4.7 ohm 1/8 5% and It still feels hot

[gec]

it is not so important that resistor get's hot. 4.7 ohm is good value. only thing u can do is buy a resistor with the same ohm value but higher wattage. but 4.7ohm 1/8W 5% resistor should be ideal. it is also importnant that the leds are soldered in series.

like this:

like i've said; it is normal for resistor to be warm or even a little hot but not so much that it can get unsoldered. bigger wattage resistor will dissipate less heat.

[Perfesser]

Good tips on the resistor Gec. Didn't know that.

Last night he said one LED has stopped working yet the others still work.

Either it's fried and shorted internally or (more likely) 2 wires have touched and shorted, bypassing that LED.

It just takes one strand of wire sticking out once the solder has hardened to poke through the shrink tubing on the wire beside it, especially when you're pulling them through a pen tube.

[gec]

just to make things clear.

explanation about serial connecting the LED's is for this case only. LED's can be connect parallel, serial or combination but it depends on the voltages and the number of the LED's

[Perfesser]

I assume he used the calculator and wiring schematic on the Freetrack website.

I recall him saying they were wired in series as your drawing above.

[Pappy]

I assume he used the calculator and wiring schematic on the Freetrack website.

I recall him saying they were wired in series as your drawing above.

Yep, wired them in series. Worked well for a while, then when i unplugged them for a few minutes to sand down the tips trying to get a better signal, the 1st LED went dim. The other two still worked, so Im not sure, Like Perf said, its probably a piece of solder poking through my insulation. Ill look at it today sometime. I have plans to go to the McMinnville air museum! http://www.sprucegoose.org/ Dont know if any of you have heard of hit. Last time I went it was still being put together, now the Spruce Goose is its main exhibit as well as a SR 71 and many others! Ill take some pictures!

Thanks again for all your help with the track stuff guys. I really hope its an easy fix. I started getting a headache trying to calibrate it perfectly last night lol my brain isnt use to flying while keep my head completly still! haha

[Pappy]

note: of course I plugged them back in after sanding! lol

[Mayhem]

I don't know if you have this working or not but. First of all you do not need to run those LEDs at their maximum brightness or really even close to it. You are running them at way to high of a forward current and that is why they are failing. Try going for 50 to 100 mA. I run mine at 50 mA all day long. In fact what you will wind up with running them higher is the camera seeing something like what you see when you stand in front of headlights. Just cause 3 volts at maybe 700mA is the MAX doesn't mean you can or should run them at MAX. You want to run at about half that in voltage and current and even then for this application it is not necessary to be that high even at half. I only run my IR LEDs at 1 volt. Some can run up to 3 volts most are 1.5 volt max but you don't need them that bright at all. I'm running off batteries so power consumption was a consideration but if I go to a smaller resistor then the one I am using 120 ohm with a 9V battery my LED points wind up way to big in the camera view like the size of dimes. What I have now is showing up on the camera about the size of a pencil eraser. OK, you wanna use 5 volts, get yourself a 50 ohm 1/4 watt resister. It will handle heat better then that 1/8 watt you are trying to run. So you will have your LEDs at 1 volt with a 50 mA forward current running off your 5 volt USB using a 50 Ohm 1/4 watt resistor and I promise you there will be no more issues and you won't be wasting power or stressing out your USB port.

[Mayhem]

By the way, I couldn't edit that message for some reason and the forum keeps signing me out quite frequently but, sorry not to get to you on this sooner just been too sidetracked chasing bandits. With my setup I go through a 9 volt battery about once every 3 or 4 months and I play a LOT. I'd estimate I am getting several hundred hours out of 1 battery and no cord. I don't know everything but I did go to school for electronics and have the certifications to prove it.

[Perfesser]

You know more about it than I do Mayhem.

So what happened here, did it fry an LED?

I think when I did mine I saw the LED calculator for my 1.6v LED's used a resistor for each one and were wired in parallel.

When I changed the setting for 1.5v it used a single resistor and the 3 LED's in series. I used that setup assuming I would have less chance of burning up an LED.

Was that correct?

The ones I used are quite bright- 100mW/sr

Rated 1.6v @ 50mA

Hell, if you're having that much trouble I could go see if the store still has em and mail em to you.

I think they were around $1 each.

I couldn't get a single resistor, they came in cards of 10 so I have a few left over.

[Mayhem]

Personally I see the parallel circuit totally unnecessary as all you are really doing is using more components though if 1 LED burns out the other 2 will work but that isn't going to do you any good as far as headtracking is concerned. 1.5 Volts at 50 mA sounds right on the money. I have many high intensity IR LEDs as I got 20 for 3 bucks straight from China so if anyone needs one or want's me to make them a hat or visor let me know just pay the shipping. If you want IR LEDs go to deal extreme I have bought many things from them. The shipping is always free but it takes about 10 to 12 days to get your order.

[Perfesser]

Parallel wiring does make it a hell of a lot easier to track down just what has ceased to function for folks without diagnostic skills.

[Mayhem]

Parallel wiring does make it a hell of a lot easier to track down just what has ceased to function for folks without diagnostic skills.

You could always just hook the LED in question to a AA battery to test it, which is how I usually do it.

[Perfesser]

I wasn't talking about you or me. I meant "those who shall remain nameless".