26mm FET Driver - MTN-26DDm - 2S-4S Input Voltage (Momentary/E.Switch)

26mm FET Driver - MTN-26DDm - 2S-4S Input Voltage (Momentary/E.Switch)
26mm FET Driver - MTN-26DDm - 2S-4S Input Voltage (Momentary/E.Switch)
Product Code: MTN-26DDm-2S+-MOM
Availability: 1
Price: $12.95

Available Options

* LVP:

* Firmware:

Turbo Timer:

* Wires + Spring Option:

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This version is for a momentary / electronic switch with 2S+ cells on the input.  If your light disconnects the power to the driver to turn on/off, then this is not the driver you need.  

This 26mm FET driver features an ultra low resistance FET that gives you near-direct-drive performance (limited mostly by your battery, LED, and connections) with the ability to still use lower power levels, among other functions such as low voltage protection.

All of the firmware options for this driver use only the FET and not the 7135.  Please reference the firmware options, below.

For the 1S (single lithium-ion cell) version, click here

For the 2S clicky version, click here.

Because each driver is hand-built and tested, This driver may take up to 10 business days to build, test, and ship.

Wires + Spring Option

There are four different options for how you would like your driver to be configured:

  1. Driver Only - No Spring or Wires 
  2. Driver + Wires Installed - No Spring 
  3. Driver + Spring - No Wires
  4. Driver + Wires + Bypassed Spring

Firmware Options (FET Only)

Standard Momentary Firmware (attiny13a)

  • Standard FET Electronic Switch.  This is for use with an external electronic switch, where the driver is always powered, not for use with a standard clicky switch where power is cut by the switch to change modes.  This option uses STAR momentary firmware, which allows you to start on either the lowest or highest mode from off with either a short tap or long press of the switch.  
    • One side of the switch is soldered to ground, the other to the pre-tinned switch pad on the driver (connected to pin 2).
  • Standard Electronic Switch Firmware Low Voltage Protection.  At the chosen LVP ramp voltage under load, the light will step down the power level.  At the chosen LVP ramp voltage level minus ~0.2V per cell under load the light will shut off.  You can override any low voltage shut down by holding down the electronic switch button.  This system gives you ample warning and attempts to extend runtime before turning the light off.  

moppydrv Multi-Group Electronic Switch Firmware (attiny13a)

For more information about this firmware, click here. 

D4 V2 UI Electronic Switch Firmware (attiny85)

  • D4 V2 Ramping.  This momentary switch firmware gives you awesome ramping control, thermal throttling, and a slew of other features.  For more information about this firmware and user interface, click here.  Source code available here.  

Turbo Timer

A turbo timer may help reduce the chance of overheating.

moppydrv / D4 V2 firmwares do NOT use a fixed turbo timer.   Instead, you program in your own turbo timer or set your temperature sensor level.


1. What Is The Input Voltage Range?

  • 6V-18V (2S-4S)
  • This is a "direct drive" driver, meaning it doesn't step up or down voltage that the LED sees.  
    • Examples of workable LED + battery combinations:
      • 2S Input (two cells in series):
        • 6V XHP50/XHP70
        • 6V MT-G2
        • Two 3V LEDs in Series
      • 3S Input (three cells in series):
        • Three 3V LEDs in series
      • 4S Input (four cells in series):
        • 12V XHP50/XHP70
        • Four 3V LEDs in series

2. What Kind Of Output Can I Expect?

  • Output is generally limited by cell selection, LED type, and other connections (such as springs and emitter wires).  

This driver was made possible and is heavily inspired by many members of the BLF flashlight community, especially comfychair (initial concept and development), Mattaus (PCB layout and development), JonnyC (firmware), DrJones (firmware), and wight (singe-sided PCB development and advice).  If you'd like to learn more about these drivers, and participate in further development, come visit our community at budgetlightforum.com 

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