Indeed, 3A is only interesting when talking about the 36v version of the MT-G2. 
Let the stacking commence!
3x KD 7135v2 boards stripped of everything but the 7135s and stacked. A total of 16x 0.380A chips on each board to deliver 6.08Amps regulated to each emitter.
Didn’t I say I would aim for 5A per emitter?…well… yeah, but sixteen chips is a much rounder number… :bigsmile:
These will be controlled by a single master board, a stripped Nanjg 105c with an Atmel MCU running some custom firmware and Zener modded for 2S input power.
This is the general layout of how I plan to mount the driver setup into the flashlight cavity.
Still need to work out the specifics but I may use this aluminium slug and drill some 17mm recesses into it to snuggly fit the slave drivers. Have it act as both a heatsink for the 7135s and a holder. The master will probably be mounted more loosely near the contact board, that way I can easily get it out and reprogram it if needed.
The bolt is a longer replacement for the one that usually holds the reflector down (standard M5 bolt from what I can tell). Just playing with ideas at the moment, there’s so much driver cavity space in this light that pretty much anything is possible. Trickiest part will be to route the 3 pairs of emitter wires through it all neatly and out to the emitters. Might be time to do some 3D mockups again.
Cheers
Linus
This is just… wow.
WOW alright.
Thanks guys, still so much to do 
That is not a microcontroller, that is a serial EEPROM.
Ah too bad, so I guess the other generic chip is the controller?
Yeap that must be it.
i hope you are taking notes on this build
because when you are done ill be sending you a valuable sum in dollars to build me one
Hehe, I do have a spreadsheet of all the parts costs but I’m afraid to total it up for fear of what I’ll see! … 
:money_mouth_face:
Just hoping the final light will be worth it
Tested the driver circuits today. Zener modded MCU board is doing it’s thing and the individual 7135 slaves are supplying the expected 6Amps to an MT-G2. This thing is dangerously bright at that output level, hence the welding glass
Lipos already slightly down after a bunch of testing, also crappy long test leads not helping hence the 5.9A on the readout. Started out stable at 6.02A.
At that drive current I measured 6.9v across the emitter so that is matching up perfectly with the graphs I was looking at. Should be resulting in well over 3000 emitter lumens too. :bigsmile:
-
Keeping an eye on the temperature of the 7135 board I didn’t notice anything too alarming running for 30s or so on high.
If my calculations are correct, on a fresh lipo input voltage of 8.4v, dropping to 7.6v once it gets to the driver and combined with this measured vF of 6.9v @ 6Amps, each 7135 driver board should “only” have to dissipate around 4.2Watts of heat.
This should be manageable and with deteriorating input voltage over time this will come down gradually from there.
In any case a little bit of heatsinking and I expect these boards should be quite happy running at these drive levels, that is until the massive amount of heat coming from the emitters overwhelms the whole situation anyway!
This is getting really fun now!
—
Edit: Don’t pay any attention to the Voltage or Wattage/Power readouts on the meter, the voltage reading on that unit has been broken since basically day one and as a result the power rating is also off considerably. Current reading is thankfully still bang on and very useful
Ok, some progress on the driver mount/heatsink.
I found an aluminium piece from an old school project that was exactly what I was looking for. I ground the OD down a bit so it would fit nicely into the driver cavity,
drilled 3 holes through the edge for the LED - wires and heavilly countersunk the center so the reflector retaining bolt could sit inside the piece neatly below the drivers. I should still be able to get my allen key in between the driver boards to the tighten/loosen the reflector bolt. It’s a bit messy right now with all the excess wiring but it should work ok.
The copper pedestals/retainers I made out of some of those copper tabs I had ordered for creating the thermal path between the emitter plate and the reflector. I reflowed them together and cut and filed them down to act as retainers for the boards. The top of each copper pedestal is flush with the driver board ground ring so I will solder some connecting tabs between the pedestal tops and the ground rings. This should hold the boards securely in place, act as the primary heatsink path for the 7135s and also supply battery negative/ground for all the drivers.
To get battery negative to the pedestals I’ll probably solder some relatively fat supply wires directly to them.
For the positive side of the circuit I’ll just run a single fat wire from the contact board through a hole in this driver board holder (which I still need to drill) and split it from there to the individual leds.
I have a little standoff on the bottom of the driver mounting assembly that will give me enough cavity space between it and the emitter plate to route the individual LED supply wires.
Here is the whole thing dropped into the driver cavity. It’s sitting considerably higher here than it will end up because the LED - wires are in the way. Haven’t drilled the led wire holes into the emitter plate yet.
Annoyingly once I had everything test assembled an LED - cable broke off and took the solder tab off one of the driver boards. So I need to fix that, those KD 7135 boards are a bit crappy and weak in that regard I’ve found. Similar thing happened on my Apex build, maybe I should have just sacrificed a few Nanjg 105s to build these slaves…
So that’s it for now.
Next I’ll look at the battery carrier modifications to deliver power from the XLR power input to the driver section. I won’t be attempting to make it 18650 compatible at this stage so that should be relatively straight forward. No way I’d get it all finished before the end of modvember otherwise!
Cheers
Linus
Yuk, did the same thing a couple of times on those KD drivers -- I don't use them ever, anymore... Even the 7135's are laid out better on a Nanjg - just find them easier to work with overall, cheaper, besides the programmability 
.
This build is look'n good! Coming along...
Yep glad to see the back of them too, that’s the last 3 I had left over
AWESOME BUILD MAN… hoping to learn something here…btw i’m new here and greetings everybody…
Thanks chris and welcome to the forum!
That battery pack is really something. Inspiring a dream of a lantern for camping with a battery pack that could be similar. Keep up the great work.
Chris, welcome to the forum!
Linus, you have continued to make good progress on the build. I like that you are taking your time and laying everything out cleanly. This is an awesome build.
Thanks Richard, working on the modified battery holder and power delivery system at the moment and it’s taking longer than expected to get everything right. Needs to be able to deliver ~20A through a twisting contact interface to the driver contact board as well as provide a twisty contact for the trigger switch circuit. It’s fiddlier than I thought it would be but I think I finally have something that will do the job.
Still waiting on the small rail to mount the handle properly to the battery tube. The first one I ordered from ebay never arrived and the reordered one from DX is taking it’s sweet time to get here as well. That’s the biggest obstacle for getting this thing finished by the end of the month, provided my modified battery carrier/power delivery setup survives the full power test in it’s current form anyway.
Boy … you are creating a monster!
congratulations! truly a wonderful job!
When you turn on the T-REX, I see it from Italy! hahha
What a Zener diode, you have to buy to replace?
Wow!