[ GXB172 - 50W Single Cell 17mm Boost Driver! ]

[schizobovine]

@clientequator

I am amaze you use XHP70 in such a small flashlight! This is very impressive!

Took some filing down on the reflector to get it to fit at all. I went with the XHP70.2 because I have been continually underwhelmed by XHP50’s. They never seem to get to the light output I expect AND it’s hard to find them in high brightness bins.

I’m defintely happier with it in the S2+ than the L2 I had it in before.

@clientequator

For the audible noise, I read in the loneoceans website that he use ultrasonic mode below 23khz to avoid audible sound. base on datasheet of mp3431, the mode pin (10) when floating should be automatically in ultrasonic mode. If low is high or low (in range), then it can become audible. My guess is maybe if you can hear it, then either pin 10 is shorted somewhere or there is some residue on pcb / leakage? Base on loneoceans layout picture it looks like pin 10 is not connected to anything so this can be a place to check?

From reading the docs, yeah, I was surprised by the noise as well. I checked the mode pin, but doesn’t look to be shorted anywhere. I figure it’s either some voodoo with PID algorithim OR (more likely) the inductor got cooked a bit during reflow and something’s loose in it. Part of why I was posting was to see if anyone else had the issue — I’m quite willing to blame it on my bad soldering rather than design, but don’t really have a good way to test short of reworking the inductor and using another (which I may yet try).

@clientequator

Is there way for you to measure power / light output of the driver?
I am curious of how bright the high mode is, and how low the lowest mode is.

Best I can do there is the dark room + lux meter method, but it’s on par with the other XHP70.2 I have (MTN direct driver for it).

@clientequator

I like your idea of using brass disc for spring. May i know when you get brass disc from?

I think I got them from MTN electronics but FastTech and Kaidomain both carry them, IIRC. For S2+’s, it’s near perfect for high-current.

@clientequator

Did you use hot air or oven to reflow the pcb components?

Hot air rework station, set at 270C. Solder was Maker Paste (which I recommend to anyone else wanting a tiny bit of lead-free for odd jobs).

One note: I’ve had problems when using hot air and lead-free solder joints being “cold”/brittle. I compensate by using a crapton of flux and a “cool down” stage. My hot air station keeps blowing even after you turn it off (until the temp hits 100C), so I just sorta keep it blowing over the board until it drops to 150C or so. Had way fewer issues with cold joints once I started doing that.

@contactcr

Current/voltage at LED and current at tail would be interesting to know.

D’oh, should have included these from the start! From a test I just did:

Moonlight ~= 12 mA
Low ~= 70mA
Medium ~= 480 mA
High ~= 2.2 A
Turbo ~= 10.8 A (!!!)

…which roughly seems in line with the output for each mode (low/50mA/250mA/1A/unlimited). I used a fully charged LG ICR18650HG2 for the test. First 4 modes were measured with my multimeter. Turbo could only be done by my clamp meter, so that 10.8A should be given a wide error range (+/-0.5A).

@contactcr

If using a brass button on the driver like schizobovine you will want to thin the ring otherwise your batteries will be way too loose. S2+ host has a lot of extra room in it as it is.

I probably should have mentioned I’m using a rather stiff tail spring bypassed with copper braid, which reduces a bit of that extra clearance. Magnet shims are usually my go-to for fixing batteries that are too short.

I think the 18350 tube is a bit tighter fit though if I recall. Age old S2+ problems I suppose.

@contactcr

User kiriba-ru sells a really nice copper single pill with a custom thin ring (pictured bottom right) that I highly recommend for this type of build:

Oooh, that is very intereting. I’d been looking at getting some spare S2+ pills, and solid copper ones would definitely be a nice upgrade. Thanks for the tip!

@clientequator

schizobovine, does the flashlight get very hot quickly?

Ooohhhhhh yeah. Minute or two on turbo before it cuts out due to thermal limits.

@moderator007

The only problem if you wanna call it that, I had was setting the temp sensor. This thing is tiny and has four legs that point straight down. Its hard to see if its reflowed on all the legs, it’s tiny and I had a magnifying headband on. I actually didn’t even see it beside the huge coil when I populated the coil side the first time.

Yeah, I had the same issue. That thing must have popped out of my tweezers 4-5 times before I finally could get it into position. I was terrified the hot air would blow it off and I’d never find it again, lol. But I focused on the other side of the inductor and the heat eventually got it to reflow over there.

It took me a few tries with the programming, too. I wound up having to flip each 3 pin side of the 2x3 pogo breakout I got, which got it working immediately. I’d figured I’d just screwed up the wiring, but maybe the pads are mirrored on the board?

To try to illustrate:

(Before)
MISO | SCLK | RST
VCC | MOSI | GND

(After)
RST | SCLK | MISO
GND | MOSI | VCC

[Schoki]

The currents you measured at the tail are on the low side. At least the highest mode.
The driver can do 19A input (and loneoceans, as well as me use that), and because it’s a switching power supply, the current goes from 0 to 19A at a rate of 600kHz. The current clamp and multimeter just measure something in between that. You need an oscilloscope to measure the current precisely.

The audible noise was there on my design too. Don’t quite know where it comes from. Either coil whine (very unlikely with molded inductors), or it could come from the “battery to brass button” connection, since the cell and driver are just held together, and not soldered (arcing, oscillation or whatever).

With my design, the noise at least got quieter with more pressure on the cell.

[moderator007]

Last night was a bad night. I had 3 of the programming pads ripped up off the pcb that I had soldered wires to.
I guess I moved the wires around to much trying to make sure I had it wired correctly.
I’m going to try soldering wires directly to the 841 appropriate pins this time, since I don’t have but 3 pads left.
Still haven’t got avrdude to talk to the 841 yet. May end up having to buying a better programmer.

[schizobovine]

@Schoki

The currents you measured at the tail are on the low side. At least the highest mode.
The driver can do 19A input (and loneoceans, as well as me use that), and because it’s a switching power supply, the current goes from 0 to 19A at a rate of 600kHz. The current clamp and multimeter just measure something in between that. You need an oscilloscope to measure the current precisely.

The audible noise was there on my design too. Don’t quite know where it comes from. Either coil whine (very unlikely with molded inductors), or it could come from the “battery to brass button” connection, since the cell and driver are just held together, and not soldered (arcing, oscillation or whatever).

With my design, the noise at least got quieter with more pressure on the cell.

Hmm, well I can see if the noise changes any if I add some spacers in there to push the cell harder against the contacts. I sadly do not have a proper oscilloscope. I can try to get the clamp meter around the LED+ wire (probably in another build) to see what it’s actually pushing out there.

I’d believe it could hit 19A in a better setup, but between the hard switch and my questionable soldering, I’m pretty happy that it can do 10A at all! Also I’m using the 4.2A max mode, as I didn’t want to push the LED beyond it’s rated limits in such a small light. It’s a lot more than what I’d expect from the raw power numbers so it may also just be running really inefficiently. Anyone want to check my math here?

Pout = Iout * Vfled = 4.2A * 6.35V ~= 26.67W
Pout = Pin * Efficiency = Pin * 0.8

Pin = Pout / 0.8
Pin = Iin * Vbatt

Iin = Pout / 0.8 / Vbatt = 26.67W / 0.8 / 3.7V ~= 8.6A

I have to crank down the efficiency to about 67% (ew) to hit 10.8A. I’ll see what numbers I get when I swap in the MOSFET based tail switch (waiting on parts for that).

[clientequator]

@schizobovine

@Schoki

The currents you measured at the tail are on the low side. At least the highest mode. The driver can do 19A input (and loneoceans, as well as me use that), and because it’s a switching power supply, the current goes from 0 to 19A at a rate of 600kHz. The current clamp and multimeter just measure something in between that. You need an oscilloscope to measure the current precisely. The audible noise was there on my design too. Don’t quite know where it comes from. Either coil whine (very unlikely with molded inductors), or it could come from the “battery to brass button” connection, since the cell and driver are just held together, and not soldered (arcing, oscillation or whatever). With my design, the noise at least got quieter with more pressure on the cell.

Hmm, well I can see if the noise changes any if I add some spacers in there to push the cell harder against the contacts. I sadly do not have a proper oscilloscope. I can try to get the clamp meter around the LED+ wire (probably in another build) to see what it’s actually pushing out there. I’d believe it could hit 19A in a better setup, but between the hard switch and my questionable soldering, I’m pretty happy that it can do 10A at all! Also I’m using the 4.2A max mode, as I didn’t want to push the LED beyond it’s rated limits in such a small light. It’s a lot more than what I’d expect from the raw power numbers so it may also just be running really inefficiently. Anyone want to check my math here? Pout = Iout * Vfled = 4.2A * 6.35V ~= 26.67W Pout = Pin * Efficiency = Pin * 0.8 Pin = Pout / 0.8 Pin = Iin * Vbatt Iin = Pout / 0.8 / Vbatt = 26.67W / 0.8 / 3.7V ~= 8.6A I have to crank down the efficiency to about 67% (ew) to hit 10.8A. I’ll see what numbers I get when I swap in the MOSFET based tail switch (waiting on parts for that).

Mr. schizobovine, do you measure the voltage (3.7V) when the driver is running? Usually when drawing big current the battery voltage will drop. Also the switch, wire and flashlight contact will have some resistance, so there is some resistance voltage drop by the time it get to the driver. Therefore it is possible the efficiency may be a bit higher than expected.

So far I got all the parts to my gxb172 and I am preparing to solder. Please wish me good luck!

[moderator007]

Pretty sure I got the pad layout correct, can someone confirm this is correct.

I still haven’t got the USBASP to recognize the attiny841 yet. Added the patch to avrdude for the 841 but it doesn’t respond. Tried Extremeburner again adding a 841 patch but no response. Tried programming a attiny85 to make sure everything was still working as before and it loaded and programmed fine. So I have done about all I know to do to get this 841 mcu to run with a USBASP programmer. Others on the wide world net had problems too but a few got it to work with the patches. I got another programmer to try out on the way, if it doesn’t work then I’ll just have to fork out some dough for a atmel programer.

If anyone has any idea how to get this 841 to work with a USBASP, your help will be most appreciated.

[contactcr]

I would link the thread to TK. She may have some advice for the programming part

[Mike_C]

@moderator007

If anyone has any idea how to get this 841 to work with a USBASP, your help will be most appreciated.

Have you tried switching that voltage jumper on them USBASPs? I have a vague memory that I had to switch at some point. If that doesn’t work I can send you over my config file for avrdude. I was using the 841 for a short time.

[Schoki]

Try to program the tiny841 without anything else on the board. The other parts could stop the USBasp from recognising the mcu (at least that’s what helped in my case with a tiny85).

[moderator007]

@Mike C

@moderator007

If anyone has any idea how to get this 841 to work with a USBASP, your help will be most appreciated.

Have you tried switching that voltage jumper on them USBASPs? I have a vague memory that I had to switch at some point. If that doesn’t work I can send you over my config file for avrdude. I was using the 841 for a short time.

I tried switching the voltage several times, no response.
PM sent

[moderator007]

@Schoki

Try to program the tiny841 without anything else on the board. The other parts could stop the USBasp from recognising the mcu (at least that’s what helped in my case with a tiny85).

I haven’t tried that yet. I do have vcc, miso and mosi connected directly to the mcu at the moment because those 3 pads ripped of the pcb from me moving the wires around to much. I will try direct connecting the other 3 and see if anything changes. Thanks for the suggestion :+1: .

[clientequator]

@moderator007

@Schoki

Try to program the tiny841 without anything else on the board. The other parts could stop the USBasp from recognising the mcu (at least that’s what helped in my case with a tiny85).

I haven’t tried that yet. I do have vcc, miso and mosi connected directly to the mcu at the moment because those 3 pads ripped of the pcb from me moving the wires around to much. I will try direct connecting the other 3 and see if anything changes. Thanks for the suggestion :+1: .

moderator007, did you get programmer to work? I am going to begin programming soon when I get the pogoprog pcb. the mcu is so small, it must be very difficult to solder wire directly to it!

[JasonWW]

@clientequator

the mcu is so small, it must be very difficult to solder wire directly to it!

You just need the right tools for the job! Lol

[Cereal_killer]

Yea no skill involved or nothin… Slather up that QFN with some solder and stick a couple wires on there with the ol’ sausage fingers.

[moderator007]

I finally got the 841 programmed using a usbasp programmer. Some idiot had 2 leads out of place on the usbasp header. Sometimes the simplest things can be over looked, I checked the pin outs a half dozen times I bet.
You will need to add the config patch file to avrdude for the 841 before it will work, avrdude doesn’t have the 841 specifications in the original config file… When I finally figured out I had the usbasp pin out wrong, avrdude found the 841 and programmed with no problem.
Tested the driver with a power supply for function everything checks good. I’m going to try to get the GXB172 installed in a S2 tonight.
Thanks for the help and the suggestions guys, greatly appreciated.
This driver really isn’t that hard to build but it is challenging to say the least. I built a second one last night in about 4 hours with a few family breaks here and there.
This time I reflowed the entire coil side in one season and then did the entire battery side at one time all but the op amp. Loneoceans has a noted the op amp is sensitive to heat and may not work correctly if overheated. So I reflowed it last by itself as quickly as possible. To me the temp sensor is the hardest part, it’s so small you have to use magnification just to see the pin reference dot for correct placement.

Thank you Loneoceans for sharing this fun and incredable driver project. :+1:

[moderator007]

@clientequator

@moderator007

@Schoki

Try to program the tiny841 without anything else on the board. The other parts could stop the USBasp from recognising the mcu (at least that’s what helped in my case with a tiny85).

I haven’t tried that yet. I do have vcc, miso and mosi connected directly to the mcu at the moment because those 3 pads ripped of the pcb from me moving the wires around to much. I will try direct connecting the other 3 and see if anything changes. Thanks for the suggestion :+1: .

moderator007, did you get programmer to work? I am going to begin programming soon when I get the pogoprog pcb. the mcu is so small, it must be very difficult to solder wire directly to it!

I did get it to work.
Soldering wires directly to the small pcb pads is difficult but soldering directly to the tiny mcu pads is even more FUN (I’m Joking of coarse). :confounded:
If you have a usbasp, you shouldn’t have to build the entire pogoprog board.

[clientequator]

@moderator007

I finally got the 841 programmed using a usbasp programmer. Some idiot had 2 leads out of place on the usbasp header. :person_facepalming: :person_facepalming: :person_facepalming: Sometimes the simplest things can be over looked, I checked the pin outs a half dozen times I bet. :confounded:
You will need to add the config patch file to avrdude for the 841 before it will work, avrdude doesn’t have the 841 specifications in the original config file… When I finally figured out I had the usbasp pin out wrong, avrdude found the 841 and programmed with no problem.
Tested the driver with a power supply for function everything checks good. I’m going to try to get the GXB172 installed in a S2 tonight.
Thanks for the help and the suggestions guys, greatly appreciated.
This driver really isn’t that hard to build but it is challenging to say the least. I built a second one last night in about 4 hours with a few family breaks here and there.
This time I reflowed the entire coil side in one season and then did the entire battery side at one time all but the op amp. Loneoceans has a noted the op amp is sensitive to heat and may not work correctly if overheated. So I reflowed it last by itself as quickly as possible. To me the temp sensor is the hardest part, it’s so small you have to use magnification just to see the pin reference dot for correct placement.

Thank you Loneoceans for sharing this fun and incredable driver project. :+1: :+1: :+1:

Mr. Moderator007, big congratulations to you!! This is another amazing result and I am very inspired by you and schizobovine for finishing gxb172 to motivate me to build also.

To build another one in 4 hour is another amazing result! I think I already spend a lot of time on just the driver soldering, but you are correct I think soldering with needle tweezer, hot air, and magnification is very important for this project. The temp sensor I use no solder, just a lot of flux and it seem to solder properly after inductor solder on.

Mr. Moderator007, I borrow ATMEL ICE programmer from friend and I will use Atmel Studio to set fuses on 841 and to program the hex file. Hope it will be able to work very soon!

[MRsDNF]

Orsm effort moderator007. Well done.

[moderator007]

Thanks for nice comments, I have seen your Orsm work MRsDNF.
I finally got around to getting this mounted in a S2 (works been crazy last few days).
This is a Orsm boost driver. I’m charging up some 30Q’s to test output with.
Already saw 2500 lumens on a partially charged 25R with the default setting.
Soldered the two bridges for the 5.5 amps output. Just waiting on the 30Q’s now.

[MRsDNF]

You probably mentioned it but what led are you using?