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

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ohaya
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L4M4 wrote:
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 :)….

ohaya
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L4M4 wrote:
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?

Responding to your 1st paragraph:

See post #140,

Quote:
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

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?

Rufusbduck
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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.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

ohaya
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Rufusbduck wrote:
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.

Rufusbduck
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The pic shows an atmel Attiny 13A. If that’s what you get then it’ll work. Haven’t ordered from them in awhile as they are a bit down the list of chosen suppliers for me simply because of the spotty checkout process(often doesn’t show a processed payment even when paypal does) but they’ve always come through for me in the end.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

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You do mean mode groups rather than modes! correct? The one linked has only two groups rather than the four usual with stars.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

ohaya
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Rufusbduck wrote:
You do mean mode groups rather than modes! correct? The one linked has only two groups rather than the four usual with stars.

Yes, sorry, you’re correct. I meant mode GROUPS

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Yes, it works and you have some reading to do. It is written, all over the place, how this is done. Plain and simple version, buy a nanjg driver that uses an Attiny 13A mcu and has a UI that you like, desolder all of the 7135 chips and solder the gate pin of the FET of your choice (RMM has several to choose from) to the pwm trace, FET source to ground, and led- wire to the FET Drain tab. The Zener mod replaces D1 with a 200 ohm resistor and solders a ~4.5V Zener diode on top of C1. As was pointed out above, the nanjg ak47A is a better choice due to the number of vias for led current to pass through the board but there are numerous Oshpark board designs that surpass it or are made to fit a variety of hosts.

Edit- RMM will also sell you a board and kit of parts for both FET and Zener builds as well as an mcu with your choice of ui’s. Not as cheap as overseas but good quality parts, fast delivery, and more choices in one place. He also answers questions.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

ohaya
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Hi,

I ended up ordering some of these from FT:

https://www.fasttech.com/p/1186301

and I’ll try them with the AOD510 and another FET when it gets in. If that doesn’t work, I know that the drivers from illumn.com work, at worst (but no mode GROUPS via click). I’ll post back here when they all arrive and I get a chance to try them.

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Removing 7135 chips is fairly easy with an adapter like this one (cut from copper sheet):

luminarium iaculator
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Any tool that can help is very good idea. Nice tool.

About 7135 removing trick without any special tools...

Tin front single pin of 7135, put solder on iron and pin and while holding soldering iron in one hand give it  gently (not savage press I really mean gently) push with toothpick from rear 3 pin side of 7135. In one moment it will pop off from driver and probably drop somewhere on the floor.

Of course driver have to be in some kind of bench vise for this method.

ohaya
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Now that I’m close to being ready to burn firmware, I was wondering if there is any other firmware that can be burned to the NANJG MCU that works with a NANJG-92 FET?

Rufusbduck
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Check out ToyKeeper’s flashlight firmware repository.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

ReManG
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So my question is if you convert one of these into a FET driver (done it 3 out of 4 times successfully) can you just leave one of the 7135’s (the one at the end of the Atiny13) on to have a FET+7135 driver, then flash it with new firmware to get regulated lows?

I don’t have the flashing stuff yet, so just a question…

ohaya
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ReManG wrote:
So my question is if you convert one of these into a FET driver (done it 3 out of 4 times successfully) can you just leave one of the 7135’s (the one at the end of the Atiny13) on to have a FET+7135 driver, then flash it with new firmware to get regulated lows?

I don’t have the flashing stuff yet, so just a question…

See post #61 – Major apparently did that, but I think he also had to mod the firmware.

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Not quite. The 7135 and the fet need to be connected to separate pins on the attiny.

ReManG
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ohaya wrote:
ReManG wrote:
So my question is if you convert one of these into a FET driver (done it 3 out of 4 times successfully) can you just leave one of the 7135’s (the one at the end of the Atiny13) on to have a FET+7135 driver, then flash it with new firmware to get regulated lows?

I don’t have the flashing stuff yet, so just a question…

See post #61 – Major apparently did that, but I think he also had to mod the firmware.

I saw that a while back, prior to looking into the flashing. It seems that you have to cut the leg #5 on the Atiny13, then jumper it over to the FET gate. This means the FET gate is not attached to where the old 7135 was attached as a “normal” mod like this is done.

I am unsure how much programming would be needed for this, I am still up in the air about what Dual PWM is…

I do wish Major would have some more pics and a little better explanation, but that guy was working it earlier in the thread…

Thanks for the answers though!!!

ohaya
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ReManG wrote:
ohaya wrote:
ReManG wrote:
So my question is if you convert one of these into a FET driver (done it 3 out of 4 times successfully) can you just leave one of the 7135’s (the one at the end of the Atiny13) on to have a FET+7135 driver, then flash it with new firmware to get regulated lows?

I don’t have the flashing stuff yet, so just a question…

See post #61 – Major apparently did that, but I think he also had to mod the firmware.

I saw that a while back, prior to looking into the flashing. It seems that you have to cut the leg #5 on the Atiny13, then jumper it over to the FET gate. This means the FET gate is not attached to where the old 7135 was attached as a “normal” mod like this is done.

I am unsure how much programming would be needed for this, I am still up in the air about what Dual PWM is…

I do wish Major would have some more pics and a little better explanation, but that guy was working it earlier in the thread…

Thanks for the answers though!!!

I’m just guessing, but looking at the screenshot of the code he took in post #41, it looks like he has one MCU output going to the 7135 (the original output, I think) and then added code to have a 2nd output to the FET Gate input.

In the screenshot he has two arrays, amc7135modes and fetmodes, and I guess the numbers in the arrays correspond to the modes vs. PWM frequencies for each of those inputs?

So, 1st mode, has:

MODE 7135 FET
= =
off 0 0
1 5 0
2 255 0
3 255 56
4 0 255

So do you see the logic there?

In mode 1, 7135 PWM is 5, and FET PWM is 0, i.e., only current via the 7135 and at low PWM.

In mode 2, 7135 PWF is 255, and FET PWM is still 0, i.e., still only current via the 7135, probably at max, or 350mA.

etc.

Something like that anyway :)…

So, it seems like what he (Major) did was:

1) Remove all 7135s except one of them
2) Add the FET, wired to MCU pin 5
3) Mod the minidrv firmware

Kind of cool hack I think :)!!

Jim

ohaya
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Hi,

I have some of these drivers coming from FT, someday soon:

https://www.fasttech.com/p/1186300

From the reviews, it’s unclear exactly what exact version, but the ones in their pics on their website shows a small cap on the battery side/spring side of the driver. Assuming that’s the case, can someone tell me if I can move that cap on to the emitter side of the driver after I clean off all of the 7135s and have added a FET? And, if so, exactly where (since the pics from comfy’s original post/thread are gone now)?

Thanks,
Jim

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Between positive and the ground ring.

It looks like you’re in the USA. Have you thought about getting some oshpark boards instead? For those in the usa it’s easier than hacking up nanjg boards imho.

ohaya
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Halo… wrote:
Between positive and the ground ring.

It looks like you’re in the USA. Have you thought about getting some oshpark boards instead? For those in the usa it’s easier than hacking up nanjg boards imho.

Ok, thanks for the info about the cap.

The nice thing about using the NANJG board is I don’t have to go buy the different parts (including the MCU), but I just did one where I am also burning firmware and it’s a pain because at least the way I do the FET, it gets in the way of the SOIC clip, so I have to desolder when I want to re-burn firmware. Does the SOIC clip fit on the MCU on the oshpark boards without removing anything?

Thanks again,
jim

Halo...
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Have you tried a hotplate / stovetop?

I think most, if not all, oshpark boards designs should take the space for a clip into consideration.

ohaya
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Halo… wrote:
Have you tried a hotplate?

I think most, if not all, oshpark boards designs should take the space for a clip into consideration.

Hi,

No, I currently use a heatgun for desoldering and reflowing.

I may do what you suggest though (oshpark that is)…

Thanks,
Jim

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Hotplate makes it easy to transfer parts from a donor nanjg to an oskpark board. A food thermometer resting on it works to keep an eye on the temp.

luminarium iaculator
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I accidentally shorted + - of this driver on upper emitter side with reflector (one layer of kapton tape for isolation on reflector bottom is not good enough Smile )

So whole flashlight smoked, battery got hot(lasted probably for 10 or more seconds), i got aware when I saw smoke.  After that accident:

- switch died

- driver remained working on one mode(high only). I will throw it away but it survived Smile

- Led survived

- Panasonic NCR18650PF survived without any issue?? Lito kala says it is fine.

So I just wanted to post my bad experience here. This is good driver and panasonic is one great cell. No explosion and it still works like a champ.

Used Djozz FET driver:

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All that current of the short went through the FET, was it the FET that smoked? Or the wires?, If that current was over the FET-specs it may just be permanently shorted. Perhaps if you just swap the FET, the driver lives again. Smile

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I potted the driver. Wires looks fine. But I will try to fan de solder all that and see what happen.

Since it works on high only  maybe only fake atiny on ak 47 died?

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luminarium iaculator wrote:

I potted the driver. Wires looks fine. But I will try to fan de solder all that and see what happen.

Since it works on high only  maybe only fake atiny on ak 47 died?

The attiny did not receive an abnormal voltage, so I would not expect it to die. The only abnormal thing that has happened to the driver is a large current through the FET.

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^

I agree.  if the only problem a reflector short (bypassing LED), the FET, cells, and driver traces would take the hit.  Are those protected cells you were using?  The protection circuits may allow the cell to work to some degree, but they can mess with mode swiching when they get messed up.  I think Ohaya had an issue like that recently.  You might want to try different cells, but I would suggest doing an autopsy on the driver first.  Makes sure nothing melted and shorted. 

You shouldn't need to pot these DD drivers to keep them cool.  They don't generate much heat.  Maybe you potted to protect wires from vibration?

luminarium iaculator
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Yes I potted to save wires from high centerfire recoils. I use AK-47 C (high, mid, low mode). This is the only one of 50 that failed by my mistake.  I just wanted to report that to you guys to be more careful than I in building or modding Smile

Bats are Pana NCR18650PF (there is no protected version of this cell on the market). I put this cells on discharge test year ago and now this happened and it survived Smile .  I don't know how but obviously it has some kind of internal protection even without added pcb's. 

I will have to scrape fujik of driver to see what happened.

 

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