Changing sense resistors and or using a potentiometer?

Hi all,

I need to be able to use a pot, with a fairly low cost driver. I will need to get about 2 amps of current at the top end.

If anyone has an idea of linear or buck driver I can do this with please let me know.

This is one driver I thought about using, but I dont understand enough about them to even know if it has a sense resistor :)

http://www.illumn.com/leds-drivers-optics-mcpcbs/ax2002-1-5a-single-mode-buck-driver-nanjg-106a.html



Thanks in advance.

Do you want to place the potentiometer inside the body of the flashlight? (Does the driver need to be round?)

It will be in a D cell maglite, the pot will be an external that protrudes from the neck. The driver does not necessarily have to be round, as long as I can fit it in the neck of the light, and heat sink it if needed.

Where you getting your pot man?

Sorry couldn’t resist, but seriously do you already have, or have picked out the the external pot yours using so we can see the spec’s?

What input voltage and 3 or 6v out?

Also are you looking for a driver that has provisions for an external pot specifically or are you ok with simply replacing / paralleling the pot to the sense resistors?

VOB it looks like someone has given this a go in the past for the AX2002 driver. Sounds like that driver gets hot at 2A. Explanation in post 138:

And here with pot hooked up in post 168:

taskled Lflex

edit: sorry, not low cost

but this one is/should run at 2A

http://www.dx.com/p/3-6v-9v-800ma-regulated-ic-circuit-board-for-cree-and-ssc-leds-4-pack-3256#.VAKQXaMjY5E

Sense resistors are typically very low ohms. Not sure pots are available in that low a range but my electronics knowledge is way out of date.

I believe these are all (Illumn, DX and Fasttech) the same AX2002 drivers:

http://www.fasttech.com/p/1105800

I have some from Fasttech that have a 2 Amp diode, the ones from Illumn I got have (SS14) 1 Amp diode. I’ve never tried to run them up to 2 amp.
Here’s the definitive review:

http://lygte-info.dk/review/DriverTest%20Anti-reverse%20Driver%20Board%20AX2002%20UK.html

I don’t know if these are really an option for you, but here they are anyway.

http://www.luxdrive.com/products/led-drivers/

The sense resistor on the AX2002 is the 'R500' right where the black wire attaches.

However... most pots small enough to do what you want are not meant for repeated adjustment, they have a very limited number of turns before the wipers start to wear out. They're really only meant to be used in a 'set it and forget it' kind of way, not like a dimmer. Pots able to withstand continuous use are much bigger than what will fit where you want it to go.

The amount of current through the pot may or may not be another issue, depends if you want to use it to completely replace the sense resistor so it can go from 0-100%, or in parallel with the resistor to give a stock output at the low end of the adjustment, plus whatever is added by the pot adjustment on the high end.

Drivers like the TaskLED stuff can use an external pot for dimming, but they do it in a totally different way. The pot doesn't carry any significant current but instead is used as a sensor input for some chip on the board that reads the pot position and adjusts output to match.