It’s time to dust of my modded Roche M170 with XHP70s and do something else with it. Original build thread here, pics dead though: Mod: BMF SRK v2 Roche Edition (Rebuilt into triple XHP 35 HI)
I never liked the XHP70’s tint or donut hole, and never bothered putting MT-G2s in it because the deep reflector makes it a little too throwy to be of use for my underground photography, so I never really used it. As it is rather throwy I thought I’d go with the flow and ordered some XHP35 HIs for it but I didn’t have a 4S driver for it at the time. As I’ve been busy with other drivers it’s just been laying around collecting dust… until now.
Here’s my new SRK style driver:
I made it both 2S2P and 4S compatible. Only battery pads + and - are “live” the other two are isolated and are to be connected by soldering wires. Here I soldered a wire between pad 2 and 3 making is 4S. To make it 2S2P I need a wire between 2 and +, and one between 3 and -. The only hardware difference is a single resistor.
The driver is a fully adjustable constant current without PWM from about 40mA up to about 8.4 amps. For low moonlight modes I use 10 bit PWM so it can go really low. I’m no electronics guy so I need easy use regulators for constant current, so I went with 12 x CAT4104s. One is adjusted with a 256 step digipot from 40mA to 0.7A, the other 11 have fixed resistors at 0.7 amps each and any number of them can be turned on or off. The 4104s may not be the best choice, but they are easy to use for an electronics noob like myself, and are very small considering they can handle 0.7 amps each. They work fine from 2.7V (haven’t tested lower) up to 25V so they are rather flexible too, but they do come with a price tag. It’s all just part of the hobby though, I’ve just wanted to make my own fully adjustable constant current driver for my SRK lights for quite some time now, and the 4104s do the job. I stuck an old re-used FET on it for testing, but won’t be using it for the XHP35 HIs, they have been reported to sometimes die above 3 amps.
I didn’t have any centering rings that work with the reflector holes, so the LEDs aren’t very well centered. The beam looks OK to me on a white wall, but I’m no beam profile snob.
I got rid of that horrible side switch I used in my original build and replaced it with my favorite lighted switch. It was a little too bright at 12V with included resistor, so I added a larger resistor to damped it a bit. I really like the protruding switches but it didn’t fit so I had to drill out the hole a bit. I made a little bit of a mess so I covered the mess up a little with a rubber washer 
Firmware flashing the 1634 is done by my usual acupuncture style method:
So here it is in it’s new configuration… A fully adjustable constant current driven triple XHP 35 HI SRK style light… For a SRK style light it is really thowy now. Not sure I’ll find any use for it, but it was just something I had to do.
