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FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > Battery question

RSS > Battery question, voltage confusion

Incisal	#1 27/02/2009 - 04h05 Top
Class : Apprenti Posts : 8 Registered on : 27/02/2009 Off line	Hello. First off, the Freetrack software and this forum are awesome. I was just about to drop 150 bucks on a commercial system, and Im very glad I didnt. Anyway... Im about to build a 3 point headset unit, and Ive used the assembly wizard, but Im not sure Im doing this right. I want to use 2 AA batteries for the power supply, so thats 3 volts. Im shooting for 30ma for the current, so I entered 2 volts for the forward voltage, which is a total guess since I know nothing about electronics. My LEDs say 3 volts, so is that the max, or do I need to supply them with 3 volts? If so I can use 3 AA batteries for a total of 4.5 volts, and step that down to 3. Can someone give me some advice please? These are my LEDs: Original Osram IR LED - SFH485P from http://www.seeedstudio.com/depot/original-osram-ir-led-sfh485p-p-69.html Wavelength, typ:880nm Current, forward If:100mA Voltage, Vf max:3V Angle, viewing:160° Case style:Radial Temperature, operating range:-40°C to +100°C Angle, full:160° Angle, half:80° Current, If av:100mA LED / lamp size:5mm / T1.3/4 Pitch:2.54mm Radiant intensity:48mW/Sr Radiant intensity, max:6.3mW/Sr Radiant intensity, min:3.15mW/Sr Time, t off:0.5µs Time, t on:0.6µs Voltage, Vf typ:3V Wavelength, peak:880nm Colour, LED:Infrared
benmeijer	#2 27/02/2009 - 12h05 Top
Class : Habitué Posts : 208 Registered on : 19/07/2008 Off line	I build my 3 point system with the same leds and also use 3V (2x 1.5 AA battery) as power. You can use 1.5 Vf and I suggest a minimum of 50 mA current/ use 30 ohm resistors. But feel free to experience with 30 mA (use 50 ohm resistors) and see if the leds are bright enough. Edited by benmeijer on 27/02/2009 at 12h09.
vagos	#3 27/02/2009 - 20h16 Top
Class : Apprenti Posts : 22 Registered on : 12/02/2009 Off line	I reccoment only 1 battery for your designs as it makes the construction much lighter. I used a single rechargable battery with 1.2V (all the rechargables are 1.2 instead of 1.5V) So my reccomendation is to use half Ohm resistors. (0.5 Ohm) in parallel as the previous figure. Outcome--> Light design, unlimited power, no running costs. Hint: This reccomendation came of from trial runs with multiple resistor types, although I have some good backround knowledge of electronics.

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