howto: Build a Nanjg-092

Of course. I have just been way too busy. Next week I have a week "off" and will be catching up on everything and posting all of the new "stuff".

Thanks CC and others. Very nice work.

The place the cap used to be located was on the VCC trace and now it’s on the +Vin trace. It does the same thing, either way? So what, exactly, does the cap do anyway?

It keeps the MCU happy

Master Slave? Possible as well with this? and you still need the zener mod for MT-G2 correct?

To control the DD effect, could you balance it out a little by just not having the high mode, like maybe 200 or 225 instead of 255 for the high mode?

Justin, yes you still need the zener mod to keep the MCU happy. That's all the zener mod effects anyways--the voltage the MCU is seeing.

I don't think you will need to master/slave this setup, the MOSFET is good to 30A+ no problem and is very low resistance. After running an MT-G2 at 10A-11A it didn't get hot at all sitting in the open air. Heat is not an issue with this.

You could definitely run a lower PWM value, which is what Comfy hinted to earlier. You could also run higher-resistance cells. (Like a a Pana B vs. a 20R or PF).

I just take off the components and flux the board, heat each pad, (or several pads at a time), with the soldering tip and wipe with a rag, as I pull the tip away. Cleans off fine. Just an alternative…

Wipe with a dry rag? Or a damp paper towel? I like that clean look, makes it much easier starting over with new components.

Thanks Justin! :slight_smile:

I usually use a paper towel, sometimes damp, sometimes dry, depending on my laziness level. A rag works a little better and dry works fine. You just have to wipe quickly. I place the rag over the tip and wipe in one motion rapidly. Excess flux is cleaned off with alcohol.

The only difference is that it used to be after the polarity protection diode (between diode & MCU), now it's before the diode (between B+ & diode). These little caps aren't polarized, so they won't explode (like the little yellow tantalum caps) if you stick the battery in backwards, so it shouldn't have any effect.

There are other places it can go on the topside and still be after the diode, but they all either interfere with either the driver fitting in the pill, or block a programming clip from attaching to the MCU. It can go from the bottom of R1 to ground, or from the bottom of the diode to ground. Both those would need a notch in the ID of the pill for clearance. It can also go between the lower tabs of the R1 & R2 resistors (since the lower tab of R2 just connects to ground anyway) which takes a little less room, but would still need a notch in the pill. If the driver is still using the 7135s, it can go from MCU pin 8 to the middle ground pin of the 7135 to the left, but that blocks the programming clip.

This type of driver can have the max current limited by using a PWM value of less than 255, but it will always be proportional only, meaning, for example, PWM=200 will give you 80% of a 20R's 8 amps, or 80% of a ICR's 5.5 amps. Changing the cell type or state of charge will change the output current, it is only regulated by the cell's voltage as compared to the LED's Vf, even at less than 100% PWM values.

^^^ But this can be a good thing... the mode spacing will remain the same, even if you change from a 8 amp cell to a 5 amp cell. Other big-current-but-regulated drivers will not maintain a pleasant-looking mode spacing if you use a cell that can't do the full max output on the high mode - mid & high end up looking too similar, and makes the reduced light output more apparent.

So the capacitor is to make sure the mcu doesn’t get a spike? And it can do this from either trace? Sure helps to have the spring side of the board completely clean and smooth, I like that.

So, let me ask you this…do you think this FET could be floated above the mcu? Made to fit on the BLF Tiny10? Thus keeping everything on one side of that tiny board? Or is this FET physically too large? Is there a smaller FET that would do that? Even if it didn’t allow so close to 100% of the battery’s potential?

I’m looking for a way to make a 10mm driver run between 2 and 3A from a 10440 cell. An Efest IMR10440 cell to be exact, which is fully capable of supplying in excess of 3A.

Yeah the cap is just like a shock absorber, or an accumulator... stores extra incoming power when the MCU turns the PWM output off, and discharges it when the PWM output switches back on. With the firmwares that work with the FET, that happens 9,400 times a second.

How in the world can anyone count em? lol Pretty cool how it all works together. Me? I get dumbassitis and can’t remember my new Convoy L4 has a side switch for modes, thought something was wrong with it as it was stuck in Hi, wouldn’t use it tonight til I could check it out. Got back inside and saw the side switch, yeah, Duh!

I’m thinking this L4 needs an FET 105c :wink:

And yes, I know. I already have a Dr. Jones Simodrv.

You'd be better off with a tweak to the layout of the BLF-10, with a much smaller SOT-23 FET in place of the single 7135. I don't know the typical pin locations of those things though, it might could work on the existing board with minor kludging. It would only be possible to get to a target of 3A by testing and finding the PWM value that gives your desired current. A different type of cell would give different output numbers.

There really aren’t cell options in this size. Every 10440 I have is an Efest IMR10440, I’ve got 12 or 14 of em For 4 lights.

In the meantime, I aim to acquire the new components to populate an 105c board and try my hand at this. I have my clip, the programmer is on the way and I’ve downloaded the pertinent software. Have yet to dig into how it all works, but am looking forward to my first driver flash. :slight_smile:

Thanks for all the great info, and again, what we would we do without ya

Wow - didn't find this thread this eve til now. I was just doing this mod when I got scared the FET would be grounding out o contact pts everywhere... It was easy to remove the 7135's, I got the FET's, but...

RMM - for your FET mount, what do you do underneath to keep it from grounding out?

I don't have to worry much bout clearance to mount the driver - it will piggyback a stock driver (made bare) in a Yezl Y3 -- stock board needs to stay for the e-switch.

It is sitting on a thin layer of JB Weld, which secures the FET and insulates it electrically.

I thought the same thing :smiley:

Will let the master let us know if it will work