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Dumpshock	#1 04/02/2008 - 06h40 Top
Class : Apprenti Posts : 6 Registered on : 04/02/2008 Off line	Hello, Recently heard about Free-Track over at the Orbiter forums. I'm wondering if I can get a little help with constructing the LED stuff. I'm planning on a 3-point cap design using the IR LED's Radioshack provides. I believe the numbers are 1.2V and 29mA. As for a power source, I'm thinking about using 2 AA Rechargeable batteries. Or a 4.5V Power Adapter (not as likely as I don't like cords attached to me while I'm at the computer.. have a tendency or forgetting they are attached.) Mostly I'm not sure about the resistor needed. I've used the Wizard on the site, inputing PSU: 1.5V LED: 1.2V 29mA I get back saying I will need a Parallel Assembly using 3 resistors with a Theoretical 10.34 Ohms Can anyone tell me how accurate I am on this and give me a few suggestions for construction? I'm still pretty new to electrical construction.
tristan68	#2 04/02/2008 - 10h23 Top
Class : Electronicien en chef Posts : 651 Registered on : 10/07/2007 Off line	Hello dumpshock 1 question : why do you use 1.5v as PSU voltage , since you say you want to use either 2xAA rechargeable batteries (so 2.4v), either a 4.5v unregulated PSU ? Did you mistype ? cya
Dumpshock	#3 04/02/2008 - 11h23 Top
Class : Apprenti Posts : 6 Registered on : 04/02/2008 Off line	Thanks for the reply Tristan, I think it was more of a misunderstanding on my part. I tried looking up the voltage on batteries earlier and it said that they were 1.5v. So, if the PSU voltage is 2.4v, I would need 3 43Ohms resistors then? Edited by Dumpshock on 04/02/2008 at 11h53.
Dumpshock	#4 04/02/2008 - 22h37 Top
Class : Apprenti Posts : 6 Registered on : 04/02/2008 Off line	I went and got the LED's. Apparently the forward current isn't as the website says. Instead of 29 mA its actually 100 mA, completely changing the resistor I need. So, changing that around in the wizard, that would mean I need a 12 Ohms resistor, correct?
tristan68	#5 05/02/2008 - 17h35 Top
Class : Electronicien en chef Posts : 651 Registered on : 10/07/2007 Off line	Hello Dumpshock 1) where did you find 100mA ? I only found 29mA (a rather strange value....) Since they're Radio Shack products, we don't know the real reference of these leds and have no real manufacturer's datasheet (which is the only info you can trust in , when unsure). 2) IF they are 100mA leds, then there's usually no need to operate them at full power. Half power or 3/4 power is often more than enough. (so 50mA to 75mA) 3) Be aware : if you use this setup with 100mA driven leds, you'll drain your batteries quickly (total current in setup : 300mA ... ouch) 4) A good way is usually to work with 4 rechargeable batteries : 4.8v this way , you can use a serial setup, which drains only 1/3 of the current a parallel setup would drain. cya.
Kestrel	#6 06/02/2008 - 01h53 Top
Class : Webmaster (admin) Posts : 780 Registered on : 13/07/2007 Off line	tristan68 @ 05/02/2008 - 17h35 a dit: A good way is usually to work with 4 rechargeable batteries : 4.8v this way , you can use a serial setup, which drains only 1/3 of the current a parallel setup would drain. Weight is a fairly significant issue though, so much so that I'm prepared to recharge the batteries more frequently, just so that I don't have to have 2 extra batteries on my head. Support FreeTrack
Dumpshock	#7 06/02/2008 - 01h54 Top
Class : Apprenti Posts : 6 Registered on : 04/02/2008 Off line	Heya Tristan, The packaging for the LED's say they are 100mA. I talked with an Electrician buddy of mine last night. What he told me about it was that I would have 3v running total from both of the AA batteries. Calculating in the 1.2v and 100mA he said I would need around a 18Ohms resistor, the lowest I could go being 15Ohms which was the closest I could find at radioshack. Replacing it shouldn't be a problem (though I'm sure the Radioshack attendee thinks I'm just abit odd having already made 3 trips in two days. ) if you think a higher Ohms would be better. I don't really have a problem with the batteries running short as they will be rechargeable and I doubt I will spend too much time at my computer. I'd like to hear your thoughts on this though
tristan68	#8 06/02/2008 - 09h41 Top
Class : Electronicien en chef Posts : 651 Registered on : 10/07/2007 Off line	Kestrel a dit: Weight is a fairly significant issue though, so much so that I'm prepared to recharge the batteries more frequently, just so that I don't have to have 2 extra batteries on my head. Agree. Since I use power adapters or belt mounted battery packs, that's not a prob for me , but weigth could cause concern if you fasten to battery clip to your cap or headset. The packaging for the LED's say they are 100mA. Ok. We'll assume they allow a max 100mA. I talked with an Electrician buddy of mine last night. What he told me about it was that I would have 3v running total from both of the AA batteries. Did you tell him you plan to use rechargeable batteries ?? Using non-rechargeable batteries, you'll get 3v by using 2 cells. Using rechargeable (NiCD or NiMH) batteries, you'll only get 2.4v using 2 cells. Calculating in the 1.2v and 100mA he said I would need around a 18Ohms resistor, the lowest I could go being 15Ohms which was the closest I could find at radioshack. Replacing it shouldn't be a problem (though I'm sure the Radioshack attendee thinks I'm just abit odd having already made 3 trips in two days. ) if you think a higher Ohms would be better. Yes , a higher resistor value would be better because : - since you calculated for 100mA, using a lower res value will take the current over the 100mA limit. - You really don't need to use your leds at full power. 50mA or 75mA are more than enough. Cya
Dumpshock	#9 07/02/2008 - 01h23 Top
Class : Apprenti Posts : 6 Registered on : 04/02/2008 Off line	Hey Tristan, thanks again for the reply. Yes, I told him that I was going to use rechargeable, maybe he didn't quite get that or didn't know that there actually was a difference. Thanks for the ProTip! So I figure I need about a 16-Ohms resistor for 75mA, currently have 15-Ohms so that should have to do the trick. I think I have everything I should need to put it together now, and I think its sorted out close enough. I'm thinking about modifying the battery pack slightly with a clip so I can choose where I want it, on my head or belt clip. Might take me a while to fully finish it up, so if you have any ideas, Id love to hear them. Thanks for the help on all this! Much appreciated. I'll post the finished product when I'm done.
Dumpshock	#10 11/02/2008 - 09h16 Top
Class : Apprenti Posts : 6 Registered on : 04/02/2008 Off line	Hello all again. I got the headset constructed and it works. Though I am having some problems with tracking. Got the MS VX-1000 cam, removed the IR filter, and have a single layer of the magnetic stuff from a floppy disk, thinking of adding a second layer. I'm getting about 25fps after unchecking all auto buttons and about 5-9 in jitter. Pitch works relatively okay, but Yaw doesnt really work at all. moving my head to the left, in game, it moves very slightly.. moving to the right, it looks over my left shoulder. Been messing with sensitivities and such with little success. Any hints? EDIT: Okay, I fixed the issue. Forgot to set in the Setup section from 3-point Clip to 3-point hat model. I'll post screens of it later. Thanks for the help! Edited by Dumpshock on 11/02/2008 at 10h49.

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