Quick notes on the KX70 driver. I received my sample yesterday, and it is a decent driver as is, but not much modding potential.
Uses the same TPS61088 as the H1-A, so we are limited to 10A on the input. Stock it is drawing almost 9A. I plan to try to push it right up to the edge, but I don’t think more than about 4.2 - 4.5A will be possible if we want regulation right up to battery cutoff.
Mode spacing is fairly close too, I really wish low was lower, as it stands low is about .75A to the emitter.
Once I get some full testing done I will be making a new thread to document all these KD boost drivers.
What i did was to grind out as much as i could for the driver and it did fit but i was afarid the components would Touch the wall so i stacked a ring made of solderwick on top of the pill to gain space… horrible move.
Had to grind the inside to realy jam the driver down and the outside so the pill woulf fit in the threads.
And flatten the backside of the reflector and remove the lens oring due to longer pill lenght.
And driver spring cut in half.
No bypassed springs and original 24 awg led wires so output is probably lacking but it works that was the main goal.
Could probably make a pill that would fit the driver better.
What if I just put the driver on the pill and screw back the battery tube to make a sandwich ?
The driver would be stuck between the pill and battery tube and I would change the battery by the tail…
Of course it would require some adjustments, like a thicker oring or maybe some solder to thicken the driver ground ring…
Probably do-able, I thought about that myself, however I have access to a lathe so I machined out a pill to get mine to fit, and it does indeed fit, just have to solder the driver to the pill as the retaining ring won’t work. I have a couple of nice S2+ builds coming up using this driver, just waiting on parts and another host.
I got another inductor core to try to continue modding the H2-C driver. The core I ordered was a T44-52 (0.44” OD, –52 core mixture), but it was actually –18 core material. This was OK because their relative permeabilities are pretty close. I could go larger than 0.44”, but I was having trouble finding the right core size with the right core material. So I wound an inductor with the T44-18 core with 4-6 turns. The DC IR was 3 mOhms, compared to 7 mOhms of the stock inductor. The new inductor did not improve the performance of the driver. With R030 sense resistor the output was still not stable with 1s input. The inductor still got very hot. I still don’t know what’s going on with the driver, but I suppose I’ll keep my eye out for a larger suitable inductor core, in case saturation of the core material is the cause of the output instability.
I ended up putting the stock inductor back on and putting the driver in a convoy L2 for use with 2x26350 cells. See more info here.
I installed the H1-A in an Convoy L2 but unfortunately shorted the LED wires with the reflector.
Then something on the driver died and produced smoke. I took it out and discovered the R025 resistor was destroyed. I tried to change it to another resistor but I think there is also some other component dead because now the driver gets hot very very fast and there is a loud noise from it.
Sooo, don’t short out the emitter wires!
Today I made C8 using XHP50.2 4000K 90CRI on DTP in OP reflector, H1-A driver and lighted by 4000K leds tailcap(10k for each led). But i have a problem: on the lowest mode when battery voltage is between 3,8-4,1V flashlight is making noise about 1-2kHz. Do you have the same or my driver is defected?
Switching regulators, like the H1-A can produce noise through “coil whine” in the inductor, other wiring, and piezoelectric effects in ceramic capacitors. I have a H2-C based light I built that makes a faint high pitched whine in low mode. In the high mode it makes a louder, lower moaning buzz sometimes. My v1 BLF X6-SE also makes faint noise in the middle modes.
As for whether these are defects, maybe. My X6 got louder when I had disrupted some of the silicone compound used to stabilize the inductor and its windings. Careful application of silicone in the right places can help quiet things down. In the case of the H1-A and H2-C, one can’t really get at the windings of shielded inductors, nor should it be necessary. Stablizing the inductor above the PCB and other components might be useful, though.
So i took 2pc 10uF 50V X7R caps and just connect them in parallel: 1 to output caps and 2nd to inductor caps, so now no more horrible “bzzzzzz” at lowest mode! Maybe it will help somebody who have the same problem.