As usual djozz I have no idea what the fet you are talking about but what you achieved is amazing, that bit I do understand. The guys mentioned are amazing talents in themselves for lots of reasons. The only thing missing is a group a group hug, whoops I mean picture. 
Nice job Djozz! And that with the prototype board. DOH, 12mm. The ones coming in the mail are half as thick. 
with all those well focused close ups it’s not apparent how small they are. You should post a picture of one next to your thumb.
Or a dime. Sorry RBD, you sorta asked for it. 
I updated the OP with a picture+thumb :-) . And here's another one with my medium sized hand (and a small size hand of the off-spring):
Nice perspective djozz. You also get my thumbs up. In all honesty this is like magic to me and we all like good magic. Thanks again.
DAGGUM that is NICE!
A real powerhouse!
Seems like maybe a custom firmware STAR V1.1 w/ a 30 second “turbo” timeout w/ moon mode might be a good way to go…
Absolutely incredible…that is one teeny pocket rocket!
Be careful though…those Efest 10440’s might not be able to push 2A for long! Don’t want you to have one cook off in your hand
I don't know either exactly what the FET is going on either inside those FETs, I am just gladly using what others have found out. I do know now that they are an almost perfect switch, as good direct drive as if they are not there at all.
(I am sure someone has made a group-hug-app somewhere :-) )
I did the test-run with the clear possibility in mind that something would blow. But nothing did, it just went skin-burning hot (I hurt my fingers switching it off, as you may hear in the video). Now that I know that it can handle this abuse, I will not be using the flashlight on high for that long anymore. These type of lights have a very effective thermal step-down: if it is too hot to hold, then switch to lower mode ;-) .
Nice! It is incredible that we have 650+ lumen flashlights the size of out thumbs these days.
Way to make it happen!
BTW. Maybe I have found a good FET to use for these small style lights.
Search the net for:
CXDM4060N
The highlights are :
Continuous Drain Current (Steady State) ID 6.0 A
rDS(ON) VGS=4.5V, ID=5.0A 30 mOhm
Qg(tot) VDS=20V, VGS=10V, ID=6.0A 12 nC
Qgs VDS=20V, VGS=10V, ID=6.0A 2.0 nC
Qgd VDS=20V, VGS=10V, ID=6.0A 2.2 nC
In a SOT89 package (same as AMC7135)
nice!
unfortunately i dont understand completely how these FETs work…
has anyone a source of wisdom for a noob?
Hey, that would be far too easy, fits straight on the tiny boards.
I think comfy has shown the leads are backwards, and by looking at the rDs 30 mOhm, comfy’s run about 4.5 or something like that
The Rds isn’t a fixed number. It’s a bit like Vf for LEDs but is voltage dependent instead of current dependent. You have to look at the plot of Rds on vs gate voltage. Most FETs aren’t fully on below 4.5v so you also have to look for one with a low gate threshold. Max current ratings and Rds on are given at the ideal voltage, sometimes 10V.
Bty Djozz. When I ordered a bunch of cells from Efest they recommended that the label be removed before use.
Djozz, cool build! Now you've got me thinking about tearing apart my Tank007 E09... I really should just leave good enough alone ya know, it is pretty good as is for an EDC but the tinkerer in me sometimes overcomes my rational side. 
led4smoke, as Warhawk-AVG pointed out, the resistance levels on that MOSFET are really high...orders of magnitude higher than the 70N02.
Djozz, awesome work! That is one tiny powerful light!
Does your 105C have low voltage shut off??
Djozz wrote:
A picture with my thumb to get some perspective how small it all is:
Wow, that is a small thumb. Sorry it's all in proportion.
Excellent build and write up. Absolutely love that light.
Please excuse this dumb question. Does that SMD Capacitor have a polarity or were you just marking positive because it's hard to tell given how close both ends are to the ground ring?
Wow! incredible mod.
Are those tiny 10mm and 12mm driver boards still available?
Ceramic capacitors aren't polarized.
RMM: thanks! I know you are a professional modder, but for others who want to mod tiny lights some of my beliefs: apart from the driver, the key to succes I believe is pay attention to every electrical connection (I used this particular light in these mods because of the lack of switch, and because it seems to have a low resistance spring), and taking very good care of the mounting of the led board: both the board and the surface must be really flat (shiny is not necessary, flat is way more important than a highly polished finish, but there will always be believers...), with very little Arctic Silver in between. Also I suspect that sometimes too little solder is used for the thermal pad of the led, making the contact surface less than optimal.
RaceR: thanks also, as far as I know and in my own experience, the 105C has low voltage warning and subsequent shut-down.