6. Batch "TA" 1S or 2S Bistro HD OTSM/NarsilM drivers 15-47.5mm size fit, S2+, C8, H03, MF01, MT03, Q8 Clicky or E-switch

7. batch now active here

Attiny 25V running Bistro HD OTSM
OTSM works perfectly with lighted tail cap and hot light no more OTC timing issues
2S Bistro OTSM now on all sizes but 15mm available, 15mm 1S OTSM implemented with design change


Attiny 85 running NarsilM v1.2 with latest version with fixed bugs
Narsil manual, a lot options to configure this one
NarsilM driver can be thermal calibrated as well
you can choose the temperature for step-down, but change it later in User Settings
the time for step-downs depends on the lights size/heat, a pocket rocket off a 14500 high drain will need a shorter time than a Convoy L6
standard will be 60°C
standard step-down time 45s

Information about this TA driver series here, notice that my drivers are developed further and have slightly different design


If you want fully assembled and tested drivers send me a PM


Available options:

there are different sizes available
15mm for 14500 lights
17mm for most Convoy, Eagle Eye, BLF A1 lights
21mm special for Skilhunt H03
20-22mm for various lights with this size
20.5mm Astrolux S42, 21mm thin board for Skilhunt H03
38.5mm Courui D01
42mm for Truenite TN42
46mm SRK, MT03
47.5mm Q8, MF01, MF02

2S boards are now available in FET+nAMCs+1AMC
FET+1+indicator LED output, by adding solder bridges to route pin out of the firmwares

This time will be using the Infineon BSC009NE2LS5IATMA1 as a high current low resistance MOSFET (1mOhm @4.2V)
You can choose a custom number of 7135 less than the maximum

Drivers will be fully tested

2S LDO mod is available for all sizes now

efficiency advantage over Fet+7135*1

this is just an example, keep in mind that triple hotrods get more gain than a single emitter light


for 17mm Board will be phosphor bronze in 2 lengths
for 15mm board the short spring fits (the long upside down but risky)
All drivers come without soldered springs, to stay below 10mm envelope thickness which is 2.2€ cheaper to ship

long spring for 20mm and larger
Or short spring

For 24-30mm boards those springs are good

I have now 0.35, 0.75, 1.0 mm² high flexible silicone wire for the drivers
0.75mm² max for 17mm drivers
0.1€ per inch
prices reduced to half of 4. batch as the shipping costs are relatively low for a bigger order

1.0mm² for 22 and 30mm drivers
0.175€ per inch


12€ Bistro HD OTSM Attiny25V

NarsilM Attiny85
12€ with temp+LVP calibration and max temperature preset,

per loose bronze spring add 0.25€
large steel spring 0.12€
springs can be soldered, but stiff long spring adds shipping
silicone cable can be soldered for 0.1-0.175€ per inch
also soldered short or large long spring plus soldered wires adds shipping cost

38.5mm +1€
46mm +2€
47.5mm MF01 MT03 Q8 +2€
Bistro OTSM 2S LDO +1€ all sizes

Bistro or NarsilM customized mode spacing adds 1-2€ depending on how many groups or ramping table you want changed
or you supply a hex add 0.5€

+1€ for SRK Size with more than 8 AMC7135 Bank with all 16 AMCs

2€ envelope priority air mail shipping worldwide
4€ for optional tracking insurance up to 25€
Soldered long phosphor bronze springs are possible, but it adds about 2.5€ shipping costs
Insurance up to 100€ adds 2€
Insurance above 100€ adds 4€

1.1€ Germany
adds 2.8€ for signed tracking + insurance up to 25€

Actual list with ordering information and also shipping

follow here the progress of your order and check if the order contains all you need

Tracking website

TA Driver sizes

15mm, new 17mm for 2 S ind. pad, 3 channel (Bistro HD),17-19mm, 17mm Oslon Black flat
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20mm, new 20mm 1S/2S LX driver, 20mm Oslon Black flat, 20.5mm Astrolux S42
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21mm, new 21mm Skilhunt H03, 20-22mm, new 20mm with 1S 3 channel AMC and 2S dual MOSFET
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24-30mm, new 2S version without AMC for more realibility, also added 2 switch LED support, 38,5mm Cuoroi D01, 42mm Niwalker BK-FA30S and Truenite TN40/42 2S
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46mm TA Haike Lite, new 46mm
47,5mm Astrolux MF01, 47,5mm BLF Q8


My other Buck/Boost driver, Tail FET, and lighted side-/tailswitch sales

LM3409 based buck-drivers

20mm, 22mm, 22mm new more efficient MOSFET and minor changes
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28-30mm, new 30mm for Convoy L6 more efficient MOSFET

Thrunite TN42, new TN40/TN42 for higher currents, Niwalker BK-FA30
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BLF GT, Astrolux MF02, Astrolux MF01, new Astrolux MF01
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Haike Lite MT07/09S, new 46mm GT and MT07/09S version more efficient MOSFET, 4S BLF Q8 and Jetbeam T6,
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high current synchronous Buck

CFT-90 BLF GigaThrower, CFT-90 Truenite TN42, Astrolux MF01/ Haikelite MT03/MT09R
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lighted tail boards

Remote FET switch/1 mode DD for Tail caps

UI and config

TA drivers

Mode groups

NarsilM v1.2

Cheat sheet

older boards

new boards are marked as my side switches

L-Lights MCU controlles
some drivers got LS for permanent LED light


*also most high current new drivers got filtering for better LVP, but this makes re flashing impossible
there is a solder bridge you can open next to small C3*

2S boards are now available in FET+x+1AMC or FET+1+indicator LED output, by adding solder bridges to change pin out

MF01 v2 TA MCPCB Mod

Hi ! ,did you made that driver I requested?How many volts does start ??? 4 ×18650 in series, or 2+2 in paralel ?
Thanks !
Astrolux mf02 custom driver for Romania.

MF02 driver is possible in 2 options

1. Buck
with 4x18650 in series for XHP35 12V, XHP50(.2) 6 or 12V, XHP70.2 12V

carrier mod is easy

Mod description here with XHP70.2

2. DD+7135
With 2S/2P for XHP50 or XHP70(.2)

Hey Lexel, how are the boost drivers coming along? I will be wanting one in 26mm (I can trim down a 30mm) to improve upon my Supfire signiture light.

Moving from 2 x 26350 to a single 26650 and having consistent output levels on turbo should be a nice upgrade. I may also switch to an xhp70.2 and SMO while I’m at it.

Anyway, now that you are using NarsilM v1.2, can the maximum ramp level be set to a certain level below turbo?

I am assuming you have to program this level before flashing the mcu, not user adjustable?

For instance, could the max ramp be set to 2.5A and then have a 6A turbo?


Any chance you would be able to flash ToyKeeper’s Anduril firmware?

Hey, may i ask for 2 drivers with max efficiency?

  1. 21mm Skilhunt H03, 1S NarsilM v1.2, step-down 50°C, SD=2,7V, PO=2B.
  2. 30mm Convoy L6, 2S NarsilM v1.2, step-down 60°C, SD=2,8V, PO=M.
    No springs or wires.

I’d like one for the MT09R 35 when ready.

:beer: You have earned a lot of respect from me for the quality of the boards you offer and your continued refinements. Thank you for continuing to offer these customizable drivers at what I consider reasonable prices. :+1:

I am right now pretty much overwhelmed by modding jobs and drivers

So it can happen that some delays occur
this also affects new boost and CFT driver

just what I have to do right now on lights to mod

Oh no! Your accepting lights to mod?

I thought you were busy before, but now you will be over run. Lol

I hope you charge a matching price for time consuming work. You have to make a profit of some kind.

Good luck. :+1:

Need help calculating cost.

I need a 15mm driver with presoldered 2x 2-icnh wires and a short spring. Plus quite a custom programming as I am going to use this board for choosing desired levels for further setups of different kinds - from mules to aspherics.

So the custom modes:
23: 1,2,3,4,5,6,7,8
24: 6,7,8,9,10,11,12,13
25: 11,12,13,14,15,16,17,18
26: 1,one7135,3,one7135,5,one7135,7,one7135
27: 6,all7135,10,all7135,14,all7135,18,all7135

Plus intl shipping


Lexel is there any possibility of a latching fet tail switch? I’ve been looking for some recently but haven’t had much luck.

you mean a normal momentary switch with a FET and a bi stable lock state?
never heared of such a thing, momentary is easy like I did in my remote FET switches

Oh, okay. The Ti tool uses them - Lumintop Tool Copper with electronic switch. Some members at cpf have made small runs of custom lights with them (kuku427, ShineOnYouCrazyDiamond, and Tain) though I have no idea where they get them. Just thought I’d ask :innocent:

Would the momentary in your remote FET switches be the same as having an e-switch tail?
The reason I ask is because if it does, then it’s only a step away from mounting an e-switch in the tail instead of having the remote pad.

I recently got a few budget lights with e-tail switches (whole driver in the tail) and really like those switches.
So I’ve been toying with the idea of converting a light to an e-tail switch with the driver in the head.

Been looking at this thread, it shows a good summary of the different methods that are possible: Mod - installing tailcap e-switch in SK58 (picture heavy)

One method is with the tailcap FET circuit, which requires a small battery or capacitor in the tail (like the Ti Tool)
Although personally I’m looking at method #4 (driver in the head) with e-switch firmware.

From my understanding the FW3A uses method #4. I think it’s kinda hard to retro fit that method to existing lights. I wish to modify some edc’s like my D25C, there is nothing wrong with the stock switch but for waking in the night I prefer a (near) silent switch.

The remote fet switches are only momentary action, meaning - push = light on / release = light off

The ti tool switch is what I want but it doesn’t need to be that small.

I noticed that the first two links in the first post go to Google and redirect. What’s up with that?