FreeTrack Forum

Hey, im building my own freetrack equipment, and i was wondering if you have to have IR leds, or can you use regular leds?  Thanks!

Red leds should work too (for example a red bike rear light) since their wavelength approaches IR light.

thanks for the quick reply!  I am kinda puzzled about how to power my 3pt. clip, is there a schematic or something that will help me with this?  i have 47 ohm resistors at my disposal, so i just need the leds, and some way to power it. THanks

Welcome to the site. Great isn't it! I just discovered it myself about 2 weeks ago and I've got a sweet workable system!

As for your question about building, have a look around to the construction gallery where people have posted their designs. There's even a ohm calculator to help you determin the proper ohms match for the power supply you're using.

Some pople have built battery powered systems that mount the battery to the brim of the cap. Others, like myself, use a wall plug in transformer to provide the DC volt supply.
Radio Shack's got LED's and of course transformers.
You'll have to decide which LED's you want, their voltage requirement, and if you want to connect them in a series circuit or a parallel circuit.

Then from there you need to pick a power source what provides enough power and adjust it with the resistors. I myself like to use the mathematical equation:

R = voltage difference between LED circuit and source / forward ohms of LED

For me I used 3 volt LED's with 20 milliamp rating. I set them up in series circuit with a 9 volt power source. NOTE: You have to factor in a higher rating for the wall transformer as they are always a bit higher than listed. If you've got a digital multimeter, use it to get an accurate voltage reading. So this was my formula:

R = 9v - 12.42v / .02A            so          R = 171

and 171 was the resistor that I had to build.

just look around a bit more and you're bound to find more goodies. Try the search too.

Cheers,
Christopher

alright, so i am going to use a 9V battery for my power supply. I am going to use these led http://www.radioshack.com/product/index.jsp?productId=2062565&cp=&sr=1&origkw=infrared+led&kw=infrared+led&parentPage=search

my question(s) is...is this the right diagram?
http://www.free-track.net/english/hardware/calcled/index.php

Is thisResistor correct?  Should i use the cap or the clip? Any preference/performance differences?  Thanks again! i cant wait to get this up and running!

Great! You've decided the power source to go with. This will now let us get into the details for your setup:

The LED's that you're choosing run on 1.2 volts and draw 29 milliamps. Now what I'm going to do is calculate a series curcuit (I assume that you do know what a series circuit is). This formula also predicts that the battery is a perfect 9 volts, batteries normally are spot on, but it's fun to just check.

O.k. let's roll:

Resistor value = 9 volt battery - 3.6 volts to run the LED circuit / .029 Amp
Resistor value = 5.4 volts / .029 Amp
Resistor value = 186.2

Your link to the resistor diagram didn't work for me so I can't check to see if you got the same.

As for the cap or clip design it kinda depends on your preference. Some folks don't like the feeling of a hat on them to use the thing. Others don't like how the clip can sometimes loose sight of a LED when the head is turned. I really don't know the difference in performance myself as I built a cap design and like it fine.

Good luck! and if anyone else here can confirm my resistor value that'd be great!

Cheers,
Christopher