You wouldn't need to modify anything for the MT-G2 in a TK61 unless you wanted to switch the carrier to 4S, then you would need to change the input parts so that they can handle the 4S input voltage.
What is the TK61/ TK75 battery carrier classified as? 4 batteries, 2 sets in series, those 2 sets are parallel, for 8.4 volts. Just trying to understand the understanding, or jargon??? How about the K40M with only 3 batteries. I understand 2,3,4, series and 2,3,4, parallel, so I’m half way there…… sort of, maybe…… I guess? :~
Stock TK61 carrier is 2S2P, or two parallel pairs of cells in series. Basically like having two bigger capacity batteries in series. There is also a voltage drop on the stock carrier not only through the springs, but through the polarity protection diodes as well. If you are running a direct drive MT-G2 the losses through the stock carrier are significant.
The K40M is 3S for short, but you could write 3S1P, or three single cells in series.
Thanks Richard, my thought for the TK61/75 carrier’s were correct,2S2P, but never realized the carrier for the K40M was 3S till I just checked the voltage at 12.6v? I have a Vinh modified TK75 carrier in my TK61 that I modded with a MTG2, FETDD and I get another 3.3 amps over the stock carrier? Even though both have the spring’s bypassed? Me thinks I have found out why now……cool!
Yep. The 3.3A difference has to be due to the removal of the diodes. In the stock light there is only 1.5A-2A maximum being drawn from the carrier. In a modified TK61 there is around 3.5A-4A maximum being drawn. A good MT-G2 light will do 8A+, so the losses will be pretty big in the carrier if the diodes are still in place.
OK , because I built 2 the same and the only difference in drivers was one had the zener and the other the regulator, that you built for me and side by side the fully modded out carrier, was quite brighter to the eye and smoked all my other (2) 26650 FETDD modded MTG2’s also. I never opened the carriers up to see the difference and I’m not going too, I’ll just keep that one in MY light. 
Thanks Richard!
Any updates with this awesome driver? This might be just the thing for my aging TK70. (3 x XM-L2, 4 x 32650). I hope this works out for the many of us who cant see very well in the dark. 
What do you mean "any updates"? The PCB and parts list have been available for over a week now and I even linked to my HEX file.
So is this the update or is there another coming? 
I would like an update like this, as i can´t build a driver on my own and i have a TK61 here with a burned driver waiting for reactivation :bigsmile:
About to embark where no monkey has gone before, the Seis Um I have here needs to be built. Banana in hand (banana plug? Hakko iron?), I wade in……
Edit: I knew something was bound to be a trip… one of the critical key components, most expensive on the list, was missing. The invoice showed it, the little anti-static bag was there with the label on it and all taped up, but it was empty. Other than that, all went well. lol
No sense resistor yet as I’m still working out what I need to use. I’ve ordered 2 more complete sets of parts and contacted them about the missing link.
Oh yeah, just left of center, the small set of pads for the Buck Integrated Circuit. At a cost of $2.70 when the entire cart full of components was only $15.38 or something like that. Oh well, surf happens.
Gorgeous, just gorgeous!
Wow... look at all that room! 
Oh the luxury! I'm so envious.
I'm wrestling right now with a set of boards destined to go into a 10W minimag.
I should take a pic of the 10mm single sided driver laying on top of that one. lol
Edit:
Got vias?
With the side benefit of letting heat escape, just brilliant!
Winner of the Nobel prize in flashlight electronics!!
Congratulations!
Arduino, eat your heart out....LOL!
Sweet Dale, very neatly put together.
I have two builds concerning those 2 drivers, the one is a well known TK61, looking to get a mile of throw from that one. The tiny driver? A one-off, Justin style. A friend of mine shoots the big S&W .500 Magnum and I have a couple of spent cartridges from that round of his. The plan is to carve a “bullet” from a Titanium bar, cut the reflector into the end like a hollow point, hollow out the back end for a copper pill that will house this 10mm driver and a 10mm SinkPAD with an XP-L on it. Figuring on a brass plunger for a small Omten clicky so it will look authentic top to bottom, and with some luck I’ll be able to steal some brass threads off something and utilize them so the “bullet” will unscrew for a 10280 battery removal. Should be good for ~1000 lumens. 
The threads are gonna be the most difficult part of that, and the mind bend going from the TK61 to a .500 Mag shell. lol
Is this driver will be flashed the MTN_momentary_temp codes ?
You REALLY need to build a small serie of thos lights! :bigsmile: :bigsmile: :bigsmile:
I’m sure SOMEONE in this forum will be very interested
Grtz
Nico
Dang near got attacked by a skunk while working on the bullet portion of the little light mentioned above. I fled for my life…
So now it’s not exactly easy to head back out to the shed to use the drill press….when you’re within 6’ of one of those little varmints and the avenue’s of escape are exactly 1, it ain’t pretty!