I’m having trouble figuring out exactly what’s going on.
I guess I’d just remove the MCU and then probe with the DMM to find out which pad is VCC for the MCU. Once I found that, I’d pull Pin1 high and low. If I can turn the buck circuit on and off that way then I’m good to go. Pin1 certainly looks like the PWM pin.
EDIT: As far as I can tell, neither Atmel nor Microchip have an 8-bit MCU with 10 pins.
Thanks wight. I tried what I said above without success. I soldered wires as follows:
I flashed the Attiny with MiniMo.
I wish I had thought to probe the MCU pads after removing the MCU. I think I picked the wrong pad for + input as I was getting a very unstable voltage to the mcu. It would fluctuate from sub 1V to 3.3V. Could have been a bad connection.
It's late. I will take another crack at it tomorrow. I wonder if I have to have the voltage divider pin (pin 7) on the Attiny13a connected for it to work. I would think that would depend on the FW. I don't think MiniMo monitors voltage.
Yeah, I don’t think MiniMo does monitor voltage. If it did, you’d want to pull the voltage monitor pin high (connect to Vcc).
When you get back to it I imagine you should be able to easily correct the situation by finding Vcc w/ your DMM.
Note that you may get better dimming results with an extremely slow PWM freq such as what we used in the Knucklehead driver thread. I wonder if I ever got around to compiling a less heinous firmware configuration for that? Probably not. I wrote about what was wrong with the current compiles and posted the code in that thread.
Sounds like good advice. I need to check out your Buck Driver thread. It was just starting when I last perused it.
Didn't get but a few minutes to work on this tonight. Definitely got different readings without the stock HX-1175b MCU in place. Some of the pins that I read + voltage on were getting the voltage from the MCU. I don't recall the readings right now. rewired the positive feed, but it still didn't work. I should have tested the MCU before wring in to the HX-1175b. Hopefully, I get a chance to take a crack at it this weekend.
You speak wise words chief wight. I tried that and got no light. I'll recheck my connections and reperform tonight and go from there. Thank you for reminding me to try that. 
I'll also pull the MCU off a "b1" board and post a picture of the underlying traces. I keep forgetting to do that. The "b" does not show traces because it is black and I have most of the bottom copper clad.
I happened across a tidbit of info about what probably allowed the driver to work when you accidentally swapped a diode for an FET. I’m not planning on looking into the matter any further, because it was definitely a bad thing to do, but it seems like what Olin Lathrop posted in this thread on stackexchange may explain why it worked at all.
Thanks wight. I tried to read it, but I'm in a rush. Sounds like it basically did not let any current flow through it. I may read it again later, but like you, I don't intend explore the possibility again. I swapped back in the diode once you made me aware of the issues.
I certainly didn't mean to swap in the FET originally. As you can see in the pics above (Post 17), with the label ground off, the diode looked just like the FET that was next too it. It was a good think that the label was not ground off on the "b1" version and that you noticed it.
I haven't had a chance to work on the driver any more. I hope to soon, but I'm starting to get concerned about finishing my scratch build light.
EDIT: Added the word "not" to the third sentence. Swear I typed it the first time.
UPDATE: The mod in this Post has a problem that will cause an over current and maybe over voltage situation. Please see the corrected mod at Post 50 below.
Finally got back to this driver tonight and got some great news. Found a good spot to tie in a PWM feed. Used Dr.Jones MiniMo FW on an Attiny13A. The HX-1175b had the stock voltage sensor resistors, but ComfyChair's 07N02 FET. Also, the HX-1175b's MCU was removed. Everything worked reliably. Did have one unexpected, but not an unwelcome result. For some reason, current to the emitter on high was twice as high as stock. Using 3S average laptop pulls I got 9.7amps to the emitter on high. Had moonlight set at 5pwm. Don't remember the current reading but I think it was like .05 amps.
This was quick and dirty work. Here is how I connected it. The red wire connected nearest the toroidal inductor is the PWM feed from the Attiny. Not sure what the component I connected to is. I think its a buck convertor. I connected to the pin closest to the inductor coil. The red wire above it that is connected to the pad next to that capacitor is the VCC feed to the Attiny. Feeds a little over 3 volts (sorry, forgot exact number).
Sounds good. What gets hot at 10A?
I wonder whether the stock duty cycle was only 50% or ??
Nice job.
I didn't run it long enough to get it that hot, but I would guess it will be the voltage sense resistors and the large diode next to the FET.
I started working on this too late to do any testing. When I do, I will report back.
50% duty cycle, Sounds possible. I really have no clue. I need to hook up an oscilloscope to a stock driver and see what it tells me. I have one, but I still haven't learned how to use it.
Ill just answer here (instead of PM). I wasnt planning on connecting anything to the TK61 driver. I was planning on replacing the driver with HX-1175B by doing a bit of "rebuilding" inside the light.
Its really nice to see you have made this progress. Looks like there is hope for me to improve the UI now. :) Not that I have the drivers yet. Tracking never worked. Dont think they ever left China. They were just reshipped. Hopefully Ill get them without issues this time. Ive been really unlucky with trying to buy more these drivers. Hopefully Ill get the right ones.
UPDATE: The mod in this Post has a problem that will cause an over current and maybe over voltage situation. Please see the corrected mod at Post 50 below.
Sounds like a good approach RaceR86.
Not sure what to make of the high current situation. Let me walk though what I did tonight just in case there is something I'm missing.
Decided to just wire up an Attiny13A by itself because I don't have room in my UF-T90 for the Nanjg 105c driver and I don't want the redundant circuits. Wired the MCU the same as the whole driver from last night. Here are a couple pics.
Looks ugly, but there are no shorts in there. So it works just like last night. All mods work fine and 9.7 amps on high. I charged up some King Kongs and put them in. All modes work fine and with the same amperage readings for all the modes except hight. High measures 13.8 amp. I didn't leave it on to see what would happen. I should note the current readings for the other modes. These are just rough approximations of what I recall. I didn't write the currents down and didn't pay close attention to the lower modes.
PWM Current
1 Too low to realy measure. Says .01 amps sometimes
3 Same as above
9 Very low. less then .05
27 About .3 amps
100 2.2 ish amps
Pulled the voltage sense resistors to see if maybe I have a short under them. Everything looks fine. Try to use the driver with no voltage sense resistors and it doesn't work (as expected). Installed one of the stock voltage sense resistors. Al modes work fine and get the same currents as above, but the resistor fries almost instantly on high. The light seems as bright as with 2 voltage sense resistors at 13.8 amps. Driver no longer works (as expected). Replace the voltage sense resistor with the remaining stock resistor just to see if process repeats. It does. Same exact behavior. It feels like the driver is going max current even with one resistor.
It's getting pretty clear whey the HX-1175B1 has such large voltage sense resistors. They are hugh. This driver was hard on the voltage sensor resistors before my Attiny swap. They were the sole source of heat before I replaced the large diode I accidentally swapped with a FET. After replaced the diode, they and the large diode produced heat.
Not sure what to do now. I guess I will try to Attiny mod one of my untouched HX-1175B1's to see what happens. I'm done a lot of experimenting on the HX-1175b. So maybe I inadvertently changed something without realizing it.
Continuing on from my last post, I tried to use higher resistance resistors. All 1206 sized.
Two R33's (Cumulative .165 ohms):
Got same current readings as above except for the high mode. High mode read 10.x amps for a couple seconds and then the resistors blew.
Four 1R0's (Cumulative .25 ohms):
Got lower current readings in all modes. PWM 100 read almost 2 amps even and High mode read almost 7 amps for a several seconds and then the resistors blew.
Next, I'm going to put this driver aside and try the Attiny swap on a fresh "B1" driver.
Keep up the good work!
ImA4Wheelr, stop and rethink. You are in DD. You have soldered PWM directly to Gate.
IMO there should be no reason for you to go directly to the buck controller with your PWM output from the ATtiny. Figure out which pin on the stock MCU controls the buck controller.
I can stop and rethink all day long, but without some basic electronics knowledge I will get nowhere. I appreciate your help wight, but please understand that I have no formal electronics training. I'm not asking to be spoon fed. Just a key word or idea will get me searching in a particular direction. I just don't have enough knowledge to know which direction to search.
I do realize it tied into the output point from the buck controller (I called it a converter above), but it was the only point that worked that far down stream. I did try to get as far down stream of the gate for a PWM feed point that would respond to connecting directly to the 3 volt "+" feed. I figured I was just sending a pulses to the gate that turn it "on and off" and that the source to the FET was regulated.
I'm going to try to use my osciliscope tonight. I bought from a surplus agency over a year ago but keep getting intimidated by it. I will try find which pin the buck controller is receiving the PWM from. Then after testing, I will pull the MCU and buck controller that take some new trace pictures for the OP.
The scope should have a test point you can use which produces a 1khz square wave or something (marked on the front). Use that to get started. I know almost nothing about scopes and can hardly use my own surplus scope.
The buck controller senses current [by measuring voltage drop over the sense resistor bank] and turns the FET on and off accordingly (and rapidly). At high input voltages the FET will be off a lot of the time (think 50% if input is double output). This is exactly what we want for regulation; other parts of the buck circuit ensure that voltage never goes too high - we don’t need to talk about how but it’s related to the rapid switching of the FET. A PWM input will tell the buck controller to keep the FET off even more in order to give lower-than-maximum modes. Keeping the FET at 100% duty cycle (always on) is direct drive. If it’s not turning on and off rapidly then maximum voltage will be allowed on the output. In a buck circuit the FET should never be at 100% duty cycle. [100% duty cycle is fine on the PWM input of the buck controller though, since this just tells it “don’t turn off any more than you normally would to maintain the current you are supposed to”]
The point of the above is to explain that the buck controller itself is in charge of regulation. If you bypass it that is bad.
I also have no formal electronics training, so you can only wave that flag at me so much ;-). I’m still happy to help.
Let’s get down to business:
FYI: In my last suggestion we are not looking for a true/accurate voltage. The DMM will probably show something inaccurate, but hopefully different, for different PWM duty cycles.
