what pot to use to dim a 5W Lux?

I'm trying to put a dimmer onto My mag to tame the 5W Lux Star.

What values do i need?

I went to a few electronics stores looking for a Pot that can take 5W/1A and has a range of 0-100hms.

nobody has one even close! they atre all ½ - 1 W only!

how are you guys dimming your maglites!??

/ubbthreads/images/graemlins/popcorn.gif I have been trying to figure out the best pot and best way to get it on my Fatman-driven Mags also.

Normally the electronics limits the power so the rating
of the pot can be much lower than the LED rating.

Greg

Although, if you put an 'l-pad' another name for that type of pot, chances are that near the bright side it will get REALLY toasty. I remember YEARS ago dimming a small 12v light with a l-pad id it smoked the second time I dimmed it.
That being said, a u-flex would work with minor modding. 8 levels of brightness and auto shut off.
Jeff

Turbo_E, Try cat# CT2154-ND (100 Ohm, 5W wirewound, $3.61) from Digikey.

Larry

I don't know about pots without using a driver, but with a fatman George recommends a 50K log taper pot. I think the audio taper is close and will work as well. Many can be found for $1-$4, it's the shaft style and size that gets tricky. It's hard to put a pot larger than 16mm in a D mag and still get the head on good. 12mm are a good size and should give you lots of options. I haven't been successful finding a 12mm pot with a knurled shaft yet. Mouser is also a good source for pots.
Good Luck,
Chris
.308

if you just need to shave some voltage and would like some control.. the 'mr al' LDO will give you both.. you can build one for $2 if you have the skills.. http://ldo.rouse.com i think is link.. I've not used it on the 5W but if the voltage is just slightly more it should work like a charm.

-awr

man...i was hoing i could find an off the shelf unit that would work, not wanting to mail order it.

hmm...what to do?

thanks for the input guys.

is your V direct-drive so you need a high-power pot? if it's driven by electronics you don't need high-power.. and in-addition.. you do not need a pot rated for the value of the emitter.. just the power lost on the pot.. i.e. if you run the thing full-open.. it will be 5W on the emitter and 0W on the pot.. as you dim it.. it will say for example... put 3W through the lux and maybe 1/2W on the pot... so you may be able to get away with a lot lower value than you think, but for 'power' pots i would only use a wire-wound pot for sure..

for testing purposes.. elektrolumens used to stock a wire-wound 100ohm resistor which would be perfect for determining the resistor value needed for a 'DD' solution.

-awr

yes, its a DD setup (5 C cells)

OK.. cool... when i've done calculations for 'resistored' LED lights.. i've never gotten over about 1 1/4W on the resistor bank even with some seriously high powered lights (like 15W+)... so my bet is that if you used a 1W wire-wound 100ohm resistor you will find (and i would certainly measure).. that the power dropped on the dimmer would be in the neighborhood of 1W or less... you can measure to find out where it's a problem.. typically when you are in the 1/2 power range the most will be lost on the pot... i.e. if you have it turned very bright.. it will be extremely low resistance so no power (i^2 x R).. and when turned very dim.. also.. no power since the current will be very low due to the high resistance.. only in the middle you have to worry about it.. so i'd buy one do some testing.. you are are already at DD so the worst you can do is melt your pot.. not hurt the emitter etc.

-awt

[ QUOTE ]
Turbo_E said:
yes, its a DD setup (5 C cells)

[/ QUOTE ]
I would suggest to use a Fatman driver and 4C batteries. It'll save you from the troubles of finding a high power pot and as a bonus you'll have a very nice regulated light. /ubbthreads/images/graemlins/cool.gif One cell less to buy/charge. Cheaper and more practical too. /ubbthreads/images/graemlins/smile.gif

I'm with Icarus.. upgrade the light to regulation.. include the dial and the light will be much more versatile... is it a 4D with 5Cs? in which case use 4D batts..

-awr

I already have 2 - 3luxeon regulated (fataman) Mags. I just wanted a "brute" flashlight, with no frills. its nowhere near as sweet, but its nice and bright. I just wanted to do thiss one cheaply, but you know in a week it'll be upgraded to regulated power. still its hard to "defend" yourself with a 2D mag VS the clubbing power of a 4D /ubbthreads/images/graemlins/wink.gif

aah... cool.. well keep us posted.. you should be able to use a dimmer that is 1W.. or.. if need be.. put a resistor in parallel to bear some load in the middle.. i.e. if you have a 100ohm resistor.. putting 100ohm in parallel.. will give you a 50ohm variable pot but in the midpoint where the pot would have the most heat.. the parallel resistor carries exactly 1/2 the power... when shorted it's shorted.. no power on either the pot or the resistor.

-awr