comfychair-inspired quick+cheap+lazy single-sided 17DD FET-driver (poor man's nanjg92)

Hi,

All I did was remove the 8 7135s, solder in the FET, then move the black wire to the tab of the FET. I remember there was some add’l steps, I think about moving a capacitor, but whas a diode suppose to be moved also? Would not moving those cause the thing not to work with the FET?

Yes, the diode has to be there - I just couldn't see it in your pictures.

What you have done should work, as long as nothing is broken, & it plays nice with that particular fet.

The cap mod was specifically for the feedback/voltage spike that was causing the attiny to reset, but your not dealing with the attiny on the FT generic board, so who knows if it'd good/bad/necessary?

FmC,

The driver I have is FT part#1127403. Is yours the same?

The one I have is a few years old, couldn't tell you the part #.

It looks the same going by your pictures.

Hi,

Sad to report that I used another driver (same type, but a new one). I tested it, then removed the 7135s, then added the AOD510, and re-wired the emitter- to the FET tab, and…. I got the same problem, high and no other modes… in other words, the same result as with the earlier board :(…

Hi,

Just so I’m clear, the essence of this was to:

1) Remove all the 7135
2) Desolder the emitter - wire from the board
3) Solder in a FET, with the Gate of the FET going to the Vdd pin pad of ONE of the 7135 locations and the source of the FET to the ground ring on the emitter side of the driver
4) Solder the emitter - wire to the tab of the FET

Mainly, that should be all right?

Yes

Hi,

Thanks. Even though I’ve already killed (yes, I try to put 7135s back but that was no good) two of my 7135 boards AND two AOD510 FETs, this is still really bugging me, plus I have a light that I wanted to put the FET driver into.

I have two of these:

rather than the “generic” NANJG from FT (now all gone) so I’m going to try just one more time (right) with one of the boards from illumn.com and an AOD510.

I really hope that that works :(!!!

Jim

So the boards don’t work if you repopulate with a 7135 when they worked before? Something else going on there as this should be a reversible operation. It may just take a bit more practice to get the soldering neat enough to work properly. It was like that for me and still is since I don’t come even close to the volume of work done by some here. Too much heat for too long can wreck parts. It’s a bit counterintuitive but slightly higher temp on the tip actually dumps less heat into the components because the solder wets more quickly, especially with flux added.

Please realize I’m grasping at straws right along with you and only trying to point out possible failure points. I mentioned the white wire above, did you ever check continuity for a short from led- to ground?

A tip for removing the 7135’s quickly and easily is to flux the chip pins and have enough solder on the iron tip to bridge all three pins so that the pads all wet at once then swipe the chip sideways toward the board edge to remove the chip. Removal this way goes much faster and dumps less heat into the remaining parts(mcu in particular). Something clamped to the board ground as a heat sink will help protect the mcu as well.

AK 47 driver is Easy Peasy I would not want to bother with other nanjgs and as Djozz described it has great + contact to other + side of driver via vias that can be solder filled.

Hi RBD,

Good news!! I put an AOD510 on one of the boards from illumn.com, and it works. Some pics:

- Removed 7135s:

Positioning the AOD510 FET:

About to test:

Success (4.0 amps test):

My new collection of used 7135s:

My conclusion is that there was something with the drivers that I got from FT (a long time ago) that made it incompatible with the FET.

Thanks everybody for your help!!

Jim

EDIT: RBD - I’ve been using a heatgun to remove the 7135s….

I should get some of those, but had this project in mind for this long weekend, and I only had the 2 FT drivers and 2 of the ones from illumn.com (latter were the ones that finally worked).

Best (= cheapest/fastest) source for AK47 drivers?

The 2-set for 2.5 dollar from dx is sold out for a while. I just bought some from banggood without memory (ak-47-C1), but perhaps for the ak-47-A1 with memory fasttech may be the cheapest: https://www.fasttech.com/product/1122400-3-amc7135-4-group-25-modes-led-flashlight-driver-c

I should’ve asked earlier: Do you, or anyone else, know of a driver that can be modded with FET that has mode groups that can be changed via clicking, rather than having to solder the stars?

That was one of the reasons I wanted to get the FET working with the FT drivers I had (the ones that didn’t work).

Thanks,
Jim

So…

This is very interesting, but because of my extreme lack of electronic-parts knowledge - Is there anybody who can write this down for a dummy?
What to buy, what to solder, where to solder, which driver works (Original Nanjg-105C from Simon?)

And… is this useable with the Zener mod on MT-G2s?

The MT-G2s that most of us use are 6V devices (there are other versions). The “Zener mod” takes advantage of the 7135 spec’ed as being able to work up to 6V, but the MCU is not, so the “zener” part of the zener mod cuts down the > 6V input voltage to voltage that the MCU can withstand.

The MOSFETs that are being used here are spec’ed much higher than 6V, so they can continue to work even with the 6V that the MT-G2 needs, but I guess design of the “splitter” part of the zener mod would need to be adjusted (again, so that the voltage to the MCU gets reduced).

I think that’s conceptually what’s involved anyway :)….

Responding to your 1st paragraph:

See post #140,

As to which driver works, I think that, theoretically, almost any of the 7135 type drivers should work, which is why I was kind of thrown off when the two drivers I tried didn’t work. There was some discussion somewhere about different PWM frequency, but I’m not convinced that that was the only reason why the drivers I tried didn’t work, since I scoped the PWM out from the MCU and that was constant (now PWM wave). So maybe it’s what someone (RBD? Or FmC?) said that maybe the MCU on some of the drivers can’t drive the MOSFET Gate input?

That was just a wag on my part about the mcu and FET gate charge as I’ve no data to back it up. Glad you got it working and stuck it out. It can be frustrating at times. This one from CNQG has switchable mode groups. IOS used to have some but not any longer.

Do you (or anyone else) know for sure that that CNQ driver will work with a FET? What I’d really like to know is a driver that is known to work with a FET AND has mode changing via clicking.