Buck and Boost Drivers, Testing, Modding, and Discussion (Pic Heavy)

:+1:

The PIC may use the EN line to shut down the TPS but I don’t even know if the PIC can sense temperature on its own.

Plus, I think LVP (cutoff, not throttling) stays intact, but the warning flashes at low voltage may disappear.

Thanks for explaining the possibility to switch the H1-A with a momentary button.
I plan to switch modes with an external microcontroller. Basically i only need two modes (33% and 100%) and i want a microcontroller or bluetooth remote to switch through the modes for me. By chance do you know the voltage and current of the pcb trace, which needs to be cut? I could measure it myself, but the driver is still in shipping.

I drew out the schematic for the AliExpress LC15 driver for 12V 12W LED:
LC15 12V 12W
…or here:
“(There is also an LC15 6V 3A version)”:https://www.aliexpress.com/store/product/22mm-3A-3000mA-1-cell-5Mode-Boost-Driver-Circuit-Board-for-Cree-XHP50-XHP50-2-6V/113294_32853667712.html?spm=2114.12010615.8148356.20.522b14086QdjU2
…or here:

And here’s the LC15 PCB layout, front side:

And rear side LC15 PCB layout:

Here is an recent image from a H1-A driver ordered 01/2019.

I need to find a way to have only two modes 33% and 100%. Because i don’t have any idea how to program a PIC, i had the idea to use an external microcontroller to switch through the modes for me. The MCLR pin seemed to be a good solution. Pulled to the ground, the PIC should do a software reset. Therefore i desoldered the MCLR-Pin from the board and pulled the pin temporarily to ground. But nothing happens. The driver just works as before.

Besides a custom firmware, which would be great, do you have any idea how to get only two modes?

Here’s a driver which will run an LED from body heat using a TEG or Peltier stack. Input voltage polarity does not matter and I found it works well. Custom Thermoelectic and TXL Group sell these boards for $19US or you can get the unipolar version for only $14 (it has half the component count).

Here are pictures of the LC15 driver for which I posted a schematic a few posts earlier:

And here’s another energy harvesting driver which will run an LED off of body heat via a Thermoelectric Peltier or TEG, only 25mV required! The resistor and capacitor in center can have two different value pairs, depending on the design revision. The caps with question marks need to be pulled off the board and measured out of circuit. They’re 0402 parts! You can buy the PCB for only $12 from the usual electronics component distributors.

Hi, please do not post embedded images, as they cause server load issues. All of the ones in this thread were just removed. Thanks.


What is considered an embedded image in this context?

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Quick question fellows, does anyone knows which type of reverse polarity protection MOSFET the H1-A driver employs? It's the small 3 pin thing at the board backside, just g00gl€d the markings but no hits. The usage of such small MOSFET is also a tad strange to me, it totally looks inadequate given the amount of input current it should handle.

Isn’t that the LDO?

Jensen567 commented something concerning reverse polarity protection in the past, now I can see it is present in the H2-C driver but not in the H1-A:

H2-C diagram

H1-A diagram

Came here with this tune in mind because a ForoLinternas fellow recently reported their H1-A driver blowing up because he tried to make it work with a cell in the wrong way. Aaaah! I understand now, master kikkoman.

Cheers ^:)

Just tried to resister mod the h2-c driver from KD. It’s is now garbage, stuck on low power blinky mode. The driver also uses an different layout (compared to the pictures in the convoy L2/l6 mod thread ). The sense resistor on my version also had an r50 instead of the r100.

The sense resistor was never an R100 in the H2-C Hellie112. Jensen567's early unit had two R100 resistors stacked, that equals 50mΩ (=R050).

Carefully check what you did to the sense resistor or other parts of the layout. “Low power blinky mode” looks to be low battery warning. If you have increased the power output and are using just 1 cell as input bear in mind other parts in the circuit causing voltage drops need to be optimized, this means good switch and well done spring bypasses or high current springs (you should optimize the current path anyway). Maybe you went overboard reducing the sense resistor.

^:)

I didn’t had much time this afternoon. Guess never mod when you are in a hurry :stuck_out_tongue: But a trace on the backside (close to the spring) was completely burned. Did a bypass but now the driver pulls 10 amps (at the battery)… no change in output when changing modes. But I still got the flashing mode…

I have a KX70 driver that has been modified exactly as Jensen567 had detailed, putting on a 2.8V LDO, moving the cap, with .01875 sense resistor. Everything seems to be working, except for one thing. The driver doesn’t fully turn off. The momentary goes through the modes using 1 press per switch, and it doesn’t seem to cycle off, so I hold to momentary down, and it seems to turn off, except the led (XHP70.2) is slightly lit, almost like a moonlight mode. Is there anything I’m missing?

Just ordered a new h2c driver.
But I got a quick question. Is this the sense resister?