Adjust power of single mode drop in module

[rodex99]

Hi,
Apologies if I am asking a daft question or the answer is elsewhere but I have searched without success.
I have successfully revitalised an old UK 400 with a 5*Cree R2 1200 lumen 5 mode . I have yet to dive with it but feel it will be anti-socially bright most of the time. (but I still want to have the brightest torch on the boat )
I now want to build my own 'perfect' dive light. I would like to use a single mode version of this module, but before turning the torch on, be able to 'dial' the required power level, without going through numerous modes.
Is this possible and how?
thanks in advance
Rod

 

[Packhorse]

There is probably a sense resistor on the driver that could be replaced by a pot. But finding out which one it is may be difficult.
The other option is swapping out the driver.

 

[AnAppleSnail]

The only easy way I can think of is to slip a resistor in series with the batteries (before the driver). That'll limit current by dropping the voltage into the driver. I've made one-speed lights into regular/moon mode versions, but at middling current you'll have trouble with resistor heating. Also there's some chance that this will toast a driver trying to pull too hard. This resistor is pretty much fixed, so you'd have to open the light like changing batteries to swap brightnesses.

Pretty much any other option requires surgery and brain surgery on the light. You'll be adding a waterproof control to change a resistor in there, which isn't easy.

 

[Packhorse]

I cant see a resistor working with a buck driver.

 

[AnAppleSnail]

I cant see a resistor working with a buck driver.

Hm! You're quite right. It could only put it into direct drive sooner, and wouldn't dim until that point.

 

[rodex99]

Thanks Guys, you seem to have confirmed that am not missing any obvious answers.
Do you think this would work?
I order a bare 5 led relector (sku 18842) and 5 Leds on premium stars(sku 15943) and 5 (sku 1883) control boards. (....and then wait a month.....)
I modify the control boards to give either 350mA or 700mA.(one per led)
I can then wire up a 6 position 2 pole switch to give
1 - 350mA to centre led (118 lumen)
2 - 700mA to centre led (207 lumen)
3 - 1050mA to centre led (271 lumen)
4 - 350 mA to all leds (590 lumen)
5 - 700mA to all leds (1030 lumen)
6 - 1050mA to all leds (1357 lumen).

How difficult would that be for a beginner. Is there any thing else I need?
I am thinking this could be run off 4 rechargable D cells or 3 non-rechargable. Will 1050mA blow the led?
The switch would need to be in the return circuits, can they be wired individually ? I assume it is usually through the reflector base.

I have a small lathe and do not think that the rotary switch sealing will be too difficult. I will probably mount it in an old UK600 housing I have as a test bed, and that already uses a rotary mechanism on the switch ( it will also have plenty of room inside for the wiring etc).
cheers
Rod

 

[Packhorse]

Makes it pretty complicated. Do you really need 6 power levels?
Also I doubt you fit 5 XR-E's on stars behind that reflector. The LEDs should all be mounted on one star.
You are probably better off just swapping out the driver from your current one.
Look for a boost driver with the levels you want and wire all 5 LEDs in series.

 

[jspeybro]

I also doubt you need all these levels. I guess 1 of the low levels (271), the mid level (590) and the highest level would be more than enough, but maybe that's just a personal preference.

DX sku 26106 could be a usable driver. There is some good information on this forum about that driver for modification. The sense resistor is known, so could be replaced by a potentiometer (or parallel), although I'm not sure if there are usable pot-meters of low resistance (a few ohm)