Reducing current on this 1 amp driver board

I am trying to find a suitable driver for a project.

I have seen this one

http://intl-outdoor.com/amc71353-5mode-circuit-board-nanjg-ak47a-p-304.html

It gives one amp output at 100%, it seems to have 3 7135 output transistors.

Now, my device as standard with the stander LED emitter takes 330mA, and at a guess..1000mA may destroy it? is that right?

So can I just take off one or two of the 7135 transistors to reduce the output current? or is there a shunt that measures and regulates output current?

It is as simple as removing the 7135s. Each of the 7135 regulator ICs is rated at 350mA. If you remove two of the 7135s, you will be at 350mA. Probably safe enough if you have the LED well heatsinked.

OK, thanks.

I was not sure if the 7135's were actual regulators or just SMD power transistors and the current was regulated.

The original lmap has a single AA cell but was thinking of replacing with a AA sized Lithium cell. Run time is not an issue, to any great degree. even if i only got 20-30 minutes on high or an hour or so on low that would be fine..

It is for a zoomie conversion, so the original LED PCB is n a small board on a 'tower; LPCB size is only 10x6mm

Can probably fit a 16mm driver board underneath, the alloy screw in heatsink. Original is slotted inside the heatsink

yea pretty much, just remove 2 chips, i usually use my wifes cuticle nipper, i just "bite off" the top, and the rest easy removed with soldering iron, a lot eaier than tryng to unsolder it in one piece. without damaging anything next to it. but my wife hates it when i do it with her things, lol.

Great, thanks

Wonder if that Led would cope with 1000mA? for a short burst? or would it just fry?

OEM driver gives it 72mA or 330mA

1st Star : Low (5%) - Medium (30%) - High (100%) - Strobe - SOS
2nd Star: Low (5%) - High (100%) - Strobe
3rd Star : Low (5%) - Medium (30%) - High (100%)
4th Star : Low (10%) - High (100%)


I find 72mA a little too bright, but high at 330 not enough.

If I used the 3 star setting, I'd get what I want. 50mA low, medium at the current 330mA, and a high at 1000mA.

OK, I'd have to be very careful not to select high for very long...or would even a few milliseconds at 1000mA just destroy the LED?

if i understand correctly the white colar covers the led, and presses it against aluminium heatsink, if that is the case, i do not see why 1A would be a problem. heatsinking wise, you are fine as it is, no need to remove chips, unless you want to drop current for another reason.

I was not so worried about heatsinking issues. I did not plan to run it at high power for any length. I was more worried that even if it it had the ultimate heatsink that the current would just be too much for that LED device.


I want the low level mainly with a very wide flood (aircraft cockpit lighting) with occasional zoom and spot at medium to high power. but for 5-10 seconds at the most

yea, but that can be done simply by switching to a lower mode. no need to permanently remove anything from a driver, (the driver you linked in a first post). your led should handle it. i can not clearly see the led, but it looks like you have xp-e led, its max current allowed is 1A.

Oh, yes, I get that, but I was worried since it is an unknown LED if it would handle the 1 amp.

If I reduced that 1 amp by a third, I'd have a
a lowed low range, approx 33 mA..but maybe that would be to low
mid of 200mA
with a full of 666 mA.

So not driving it too hard, but still giving usable mid ranges.

Until I try, no way I will know.

I'll order a pair of them and find a local supply of 14500 Li cells and see what i can do.

i do not think it works like that, changing brightness is done, by PWM(pulse width modulation) i do not think removing 2\3 of amc borads, will drop the modes by proportional number. you can use that "formula " for high\max mode, but i'm not sure it works same way for modes in between.

but regardless, assuming your heatpath is good, your led will handle 1A with no problem.

OK, so may be not totally proportional, but reducing current has to reduce light output.
Yes PWM is another way, but current reduction also does it. OK maybe not linear, but i am not so concerned with accurate figures at this point.

the problem with the original driver is that it does not have a memory mode. so if I want low power I have to first cycle through the high power mode.

The option of having a 3 mode instead of two mode is just a bonus. The actual levels are largely immaterial, as long as the low output is lower or comparable tot eh current 72mA, and a high is equal to or greater than the original 330mA

If I got a lower low, with say 50mA, a mid of approx 200 and a high of 600 that would be great.
if it the med and high were either side, that is not a great importance as long as I don't cook the LED and get my low mode with the wide flood this zoomie produces.

More in a similar vein here this is the actual lamp

FWIW that emitter looks like an XP-E to me. It should handle 1000ma just fine.
Also, the output levels on the driver are listed in percentages so removing regulators would indeed lower outputs across all levels. I have removed regulators on those boards before but unfortunately I didn't read amperage before and after to compare.

Thanks for that
I have sent a second mail to Suprabeam asking about the emitter type earlier today to see if they will tell me.
They were very helpful in info on stripping it down and are interested to know how I get on with the mod.

So hopefully they can confirm type in the morning.

Thanks


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What is your power source? Remember, the input voltage is 2.9V-4.5V. It'll only work with a 14500 (li-ion) cell. It won't work with nimh or alkaline based AA cells.

If it is an XP-E, as think2x said, even at 1A, that LED will be able to handle it. Just make sure it is firmly seated on that aluminium tower so the heat produced goes towards the rest of the pill.

The plan was a 14500 AA sized lithium cell,

The ones seen so far only have 900mAh or so, but I don't need huge run times. On a low moonlight mode 45 - 60 minutes with odd 10 second bursts at medium 200 lumen ish power levels.
Almost never on the 100% level. But as yet I can't find another driver board that is lower current and has memory and /or low power on first with no strobe function

Ideal ( easiest ) for me would be a AA 1.2-1.5 volt driver with
Low moonlight first 10-15 lumen or so
Mid to high 170-200

And nice but not necessary high at whatever the LED can handle. so maybe with 'Turbo timer'

If driven by 1.2-1.5 volt AA even better, but so far not come across one .

Hence the thought to swap to a lithium AA cell.

Also looking at turning my own body on lathe to take an 18650, but my thread cutting is a bit 'shaky'.


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I asked the question about the body here


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Reply from Suprabeam

The LED is a XP-G2 so according to Cree data sheet, max current is 1500mA




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Well an XP-G@ would have a silver boarder instead of a green one. That emitter is likely an XP-G (Gen1), still 1500ma drive current. I'd say go on and use the 1000ma driver, FWIW on high level with that driver with a quality 14500 you should get 35-45 minutes runtime