FreeTrack Forum

I am making a single point hat with 1 LED.

How long can can I expect the battery to last of a single AAA battery. Also which resister should I use?

I have tried the wizard thing and its not working for me, it just keeps resetting itself.

Thanks in advance

You will need to use two standard alkaline batteries for proper operation.
AA batteries will last about twice as long as AAA's.

Fresh batteries are 1.5 Volt. Dead batteries are .8 Volt.
Vf of LED(SFH485P) is 1. 5 Volt.

3 Volt-Vf=1.5 Volt. Need to drop 1.5 Volt. Using a 22 Ohm resistor gives a current of 68 mA with fresh batteries. When batteries are at
1 Volt each. the current will be 23 mA. This value resistor will give a good voltage range of operation for optimal battery life.

Here is a spec sheet.

http://www1.duracell.com/oem/Pdf/others/ATB-5.pdf

With 50 mA average, you may get about 40 hours of operation with AA size.
With AAA you may get 20 hours.
Educated guess.

3-1.5=1.5
1.5/22=68 mA (using 22 ohm resistor)

Or you could use two D type batteries and it will run forever.  

If your camera has IR leds you could even turn them on and glue some reflexive spot on your forehead! That would be nice setup!