Is there a maximum amount of 7135s this can control/be a master too?
In my opinion: 1-2 or max. 3 of additional AMCs on board (105C) should not cause a problem (if You correctly cooling them in flashlight). But You must keep in mind that the electrical connections in this driver was not designed for currents like 4-6A.
PS. I can always (if remove orginal MCU anyway) drill a hole in PCB + connection to other side of driver and solder there copper wire from one side to another. Also can solder better connections between AMC current stabilized ground 
Ive done a total of 16 before on more than one occasion. 5,9A on a single 105C (Qlite). I have seen others go higher on a single board...
I have seen master/slave setups around the 15A range. (Something I will do soon too, not with the one Im buying from you, but I might try that out too.)
If that can be done with a regular 105C, I would assume yours can handle it just as well?
Do you or anyone know if there is an upper limit if you master/slave 105C drivers with 8-12x7135 on each board? Can a 20A driver be made? 0:) (Im aware of possible issues with switch, spring, etc ..)
(picture from DrJones)
Oh, let me help.
This has been discussed before - in the big mammuth thread 
- from post #164 (look here) thru post #177 (Especially read #171).
Ah, thanks! I figured it had to be somewhere in the monster thread.
Thanks sixty.
RaceR86: why not use direct drive for outputs above 5A?
Seems silly to me to stack many boards to get a current that you can get with a single FET.
Unless of course you specifically need the current limited to a certain value.
Two improvements have been made:
- increased speed of PWM
- thermal protection now works more smoothly (hardly noticeable to the eye when reducing brightness)
We are thinking also about implementing additional/alternative method of temperature treshold adjustment (after some multicliks driver turns on in 100% mode, then by touch, when sense max. safe temperature You click and from now on this “touched temperature” is written as a max. temperature treshold. What U think fellows?
Ah, I had the same idea (for setting the temperature limit) a few days ago and had noted it on my to-do list for my bigger drivers. So obviously I like it :) The user should be advised to do that temperature threshold configuration with full batteries.
I personally like to see a noticeable step in brightness when thermal protection kicks in, but that's just my taste.
What's the reason for increasing the PWM speed?
Because, it was in my opinion, a little bit too much audible in previous version of thermal protection mechanism (therefore we modified both)
how about some kind of notification that output is being reduced due to temperature, it would be nice to know that heat shedding is not sufficient, and one can even test different environments to figure out how long the light can maintain output before temperature induced reduction (and even compare between lights)
Oh man I get headache just for reading all the modes and configuring stuff…a factory reset seems like a good idea(drJones should also build this feature in his drivers, hint hint 
)
I am away from all these configurable modes and stuff because I always got confused from it.
I just use some plain brightness levels or the ramping…
One question do you also solder a bigger wire between VCC and the plate, or just the plate on top of the stock spring?
The one click/two click mode change seems to be a really good thing, that is the best. It impresses me.
Sorry but I am little busy today 
About springs and contacts: Put this into translator: avoiding voltage drop at the terminals
Bocian: Didn't you already use 16kHz? I definitely can't hear that. But younger ears can hear higher frequencies. So what frequency do you use now?
Werner: Yes, my bigger firmwares (i.e. those not restricted to ATtiny13's 1kB) have a factory reset.
This is fantastic project
Does the zener modification work in order to use two cells with this driver? Some features disabled?
Feel free to guide me to any decent direct drive drivers that I can buy.
Final version of extended Attiny25V driver has been established. Final PWM speed is 16,5kHz. Added: auto-calibration of temperature safety treshold invoked by 9-clik (when assembled in flashlight: driver start in 100% mode, lamps head getting warm, then by touch, when sense max. safe temperature, by any click this “touched temperature” is written as a max. temperature treshold).
Final version of programmable Attiny13A driver has been established. Final PWM speed is 18kHz. Decription below:
Navigating between modes works two-way. One click makes you move to another mode in the loop, double click takes you back to the previous one. It allows us to; for instance, reduce brightness without clicking through stronger modes in the loop. After reaching the verge of the loop, moving further will cause „a jump” to the next verge of the loop.
The programming procedure of a given mode is elicited by 6-click, while being in the mode we wish to change. Displaying the sequence occurs in the lowest mode (signaled by one twinkle) upwards. Every mode displays for about 1,5 of a second. After reaching 100% there’s one twinkle, then it displays modes downwards. The mode is programmed during the display invoked by a click or by the mechanism of turning off the switcher. If we cease to do anything during the procedure of presenting modes upwards and downwards, the light brightness will remain as previously set.
Brightness level palette available in the programming process:
0,02% (not always visible - depends on variability of electronic components parameters ).
0,15%
1%
4%
10%
18%
25%
32%
50%
70%
100%
Stroboscope (The strobo) mode is invoked by 3-click. The intensity of the flashes is the same as in the mode we have invoked the stroboscope, and has an optimal frequency 2Hz.
Simplified battery cell voltage measurement under full load is invoked by a 4-click. After invoking a 4-click, the lamp flashes for a short moment in 100, then the measurement happens. After that, with a number of flashes in 20 mode, the driver informs us about detected voltage range:
- 5 flashes means 3,8-4,0V
- 4 flashes means 3,6-3,8V
- 3 flashes means 3,4-3,6V
- 2 flashes means 3,2-3,4V
- 1 flash means 3,0-3,2V
- no flash means 3,0V (in a moment there will be low battery cell voltage warning starts).
RESET to factory settings (modes to: 0,15; 10; 32; 100. Inovoked by 8-click.
The low battery cell voltage warning starts when the cell, in a working mode reaches about 2,9-3,0V. Then a single flash appears and a reduction to another, lower level from the programmable modes palette (we reach ~2,9V in the given mode, and after a flash, we drop to another, lower mode). This works to the level 3 (1). When this happens the lamp will retain this level, flashing periodically every 10 seconds. After reaching 2,8V you will experience the last mode reduction to 2 (0,15). After reaching critically low voltage 2,6V, the driver 4 flashes and goes into sleep mode.