I would like to mount a TSAL6400 led on a single AA size battery box, with a simple ON/OFF switch. My problem is that the LED needs exactly 1.35V to function at its rated brightness. At this voltage it uses 100 mA current.
I would like to use Sanyo Eneloop batteries. I've measured them and they have 1.405V one day after charging. I think they will drop to about 1.395V @ 100mA.
I've followed the LED tutorials, which all say I have to wire a resistor in serial with the LED. My problem is that if I calculate, that resistor needs to have (1.4-1.35)/0.1 = 0.5 Ohm resistance.
My question is that what would you recommend me to do this project? I would like to make the box as little as possible, I'm planning on mounting everything directly on a single AA box.
- Shell I use two 1 Ohm resistors in parallel, to get a 0.5 Ohm resistor?
- Can I possibily use some micro turn potentiometers for my problem? It would be the best solution, as then I could just use different batteries, as all I would need to do is to set it after changing batteries. I am mostly interested in this solution. Can someone explain to me what is the best way to get 1.35V from 1.4V-1.6V sources using a simple potentiometer?
- Maybe it's an overkill, and I really don't know how to use them, but can I use a voltage regulator for this purpose? I mean is there a voltage regulator which is small and can provide as little as 0.4V drop?
UPDATE: I've made some measurements on my LED:
- 1.184 V - 12 mA
- 1.315 V - 75 mA
- 1.345 V - 93 mA
- 1.357 V - 100 mA
- 1.380 V - 110 mA
The last one is when I connected it directly to a Eneloop AA battery. By definition it's overdriving, but I don't know how dangerous it is for the LED.