FreeTrack Forum

Hi,
I'm trying to build myself a 3-point IR track clip, and I just need a little hand with the wiring. I plan to use a 3V Lithium coin cell to power it, and I'm a little unsure of what resistors to use. I'm using three Osram LD271 IR emitters for the clip, as well as a 3mm red LED (so that I know if it's turned on). The red LED has a forward voltage of 2.5v at 20ma, and forward current of 25ma. I'm having a little difficulty with the IR LEDs. The datasheet, here: http://catalog.osram-os.com/catalogue/catalogue.do?act=downloadFile&favOid=020000030000d0df000100b6 gives two different values, and I don't know which one to use. Additionally, I haven't been able to get the assembly wizard to work, so some help with which resistor to use would be appreciated.
Thanks in advance for any help.

For LD271, use a forward voltage of 1.3V and choose a current less than 100mA. Since you're using a tiny battery you should use the lowest current you can get away with. Try 20mA, if that's not bright enough then take it higher to, say, 40mA. The LD271 has a narrow spread of +/- 25 degrees so you'll need to sand the lens tips down to make them wide angle.

Hello Sgt Powderhound.

Additionally, I haven't been able to get the assembly wizard to work

Could you please provide some feedback, so we can improve the wizard ??
All informations would be much appreciated.

Thanks in advance.