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.
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.
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
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!
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.
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.
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 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:
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.
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!
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.
