Driver Info: HX-1175b & HX-1175B1 (Pic Heavy)

That’s something I might try with my Y3. RMM said he put two 25v 22uF capacitors on the output to absorb the spike when you turn it on. :slight_smile:

And then he said that it didn’t work. Keep reading.

Couldn’t hurt though… It seems it was a minor success anyway. Maybe a bigger capacity cap. Or mess with a resistor to let it fill slower. Like 1-2 secs till it reaches voltage. I used to do a lot of that with relays, to add a delay to relays. Also had 1 farad cap storage (huge bank of caps back in the 90s) to keep the draw from the alternator consistent. This stuff is all coming back to me. But the big cap remember really helped smooth things out in the voltage department and kept the voltage stable from the regulator. It might work if it was just a bigger cap- I’m not sure if they make ceramic caps that big though, or if there’s enough room. I might try it though, like with a regular japanese cap to test and see if the spike is there on the lower end before and after.

I mean it can’t hurt to put it in there. The cap would make it kind of cool too cause the light would fade out

You might learn something from doing it. It won’t do any of the things you think it will, although it won’t do much bad either.

Among other important points, understand that this driver (like other buck drivers) probably operates somewhere in the range of 1,000 to 1,000,000 cycles per second. RMM was attempting to smooth out the “turn on” spike during each of those cycles. Not some spike when the light itself is turned on.

The cap will certainly not cause any fade in or out.

As far as resistors - I cannot think of any configuration of caps and resistors that makes sense on the output side.

Just to further clarify - anything that you do which takes 1 second to take effect will not help with an LED that gets blown in under 0.001 seconds.

Unfortunately I think the truth of the matter is that the effect of adding an output cap will be so minuscule as to be undetectable without an oscilloscope. So you probably won’t learn from doing it unless you have and use a scope.

If you’re really interested in getting back on your feet with electronics and relating that to flashlights, I’d recommend figuring out current sensing. It doesn’t seem like you have a handle on that yet, and that’s a pretty basic concept. It revolves around applying Ohm’s Law. It’s hard for me to see how you’re going to either achieve or learn anything just by throwing parts at a problem which you don’t have.

Yeah your right though- never really got into power supplies. More plc programming and cooling components was my thing, and programming, wifi, car stereo… I’m just throwing stuff out there, doesn’t mean I’m right. It’s good to have other people’s experience, even in other fields cause then someone like you who understands it better might look at a different angle. :slight_smile:

I mean if I posted half the stuff I’ve made over the years you’d sheet your pants. I don’t study basic electronics but I know enough to get it working. I’m a welder, machinist, pretty much jack of all trades. Trying my hand at flashlights- which to tell you the truth is a bit deeper than I expected :slight_smile: But that’s awesome

From my experience the cap will keep the lights on till it drained. But were talking 1 farad so :slight_smile: I was thinking if you add a resistor, that would give the cap time to put a drain on the emitter current till it filled. But if your saying the driver cycled and the spikes happen each cycle- then that makes sense, doesn’t work.

I’ve never used this driver with MT-G before, so is this normal behavior?
I tested with new fully charged 18650B. Perhaps my test was flawed.
The MTG was from a newly ordered batch.
I can’t repeat the test per say, as the driver is now installed in a light, and the emitter is in a box. I could test again using the same emitter and a different new HX1175B.
Anyone else driving MT-G2 with two cells with this driver?

I don't recall ever trying to measure the driver with 2S cells. I will do my best to measure a new stock driver with 2S and then 3S tonight.

I just received the buck converter wight recommended to me in another thread. I will also try to get around to swapping the buck converter on my broken diver and hope it does the trick.

That would be great. After I tested with two cells, all I did was add a magnet and a third cell, so I think my test was true.
The driver I used came out of another light (the same one relic is driving 3xMT-G2 with) I do have some brand new ones on hand.

Some odd test results of HX1175B and MT-G2

I tested three different HX1175B with MT-G2. Here are my results.

With 2 x 18650

Driver A - 3.5A

Driver B - 4.2A

Driver C - 4.8A

With 3 x 18650

Driver A - 7A

Driver B - 13A

Driver C - 6.8A

These are my results. I can't explain them, especially the 13A. All the modes were functioning, and I could feel it heating up fast. It kind of scared me.

Please check the markings on the sense resistors of each driver (A/B/C) and post your results.

B and C have R068 resistors. A is already wired into my Boxer, but probably the same.

Thanks. If possible I’d like to know the voltage drop across the sense resistor bank of each one while using 3s batteries. You can simply put your meter in the 2V range and put a probe on either side of the sense resistors. I’ll admit that this may not tell us much. The behavior does seem odd and that is the first place I can think of to check. The idea is to help narrow down the problem. If the voltage drop is ~0.25v at 13A then we can assume that the sense resistors are low quality and that the values do not match the markings. If the voltage is significantly higher than 0.25v then we will say that something else (the buck controller) is acting up.

I can’t do it right now. Everything has been desoldered and put away. All my work is done on my kitchen table…and I have to eat. If I have time, maybe tomorrow.

Do I test each resistor separately, or bridge both at the same time with my probes.
You’re luring me into realms that are beyond my understanding.

Edit: I assume this should be done while the emitter is blasting away? The driver might not last long enough to do the test going at 13A. It got real hot almost instantly.

The resistors are all in parallel so any points on either side should be equivalent. You would have to remove them to get individual values. I think what you’re looking at is how each set compares with each other set to see if that’s where the difference in output lies.

  • The resistors are electrically parallel, so you can just test one - the result is the same no matter which one you you test. You can even put one probe on the lefthand end of resistor A and the other probe on the righthand end of resistor B. The voltage drop across the bank will be the same regardless of where your measurement points are.
  • Yes, you’ll need to do it while the emitter is blasting away. You don’t have a lot of choice in the case of that 13A driver, you’ve got to figure out what’s wrong with it so that it can be repaired… otherwise it’s a waste of a $10-15 if it’s not use-able like it is. I’d get my emitter covered with a shield (to protect my eyese), get my probes set up firmly in one hand to measure voltage drop one-handed, and then complete the circuit with my other hand while watching the DMM.

I’m definitely looking forward to your results if you decide to take the time to do the test.

EDIT: RBD is correct - I just want to know how the sets compare to each other as a whole right now, no need to remove anything.

I’m also worrying about frying my MTG at 13A
Edit: And if it’s a 7A buck driver, why not 7A with two cells? LCK 5A buck gives 5A with two cells.

If it starts on a room temperature heatsink of decent size it should survive a few seconds to get the voltage drop for sure. You’ve got to be strict with yourself, if you fumble the probes - stop and turn the thing off. I wouldn’t waste time fiddling with the thing while it’s on, despite djozz showing that his emitter survived 16A. Do not do any testing without a heatsink. You should get a stable enough figure immediately, so it’s only a matter of the time it takes you to look at the DMM and note the reading.

I have it clamped to a ten pound slab of copper.

In that case I think you’re golden :-).

Sounds like it’s dropping out of regulation. That’s a huge dropout voltage though (>1v?). Above a certain point I assume it regulates pretty cleanly. Maybe this is related to the Zener used to power the QX9920, note that SF uses the QX9920 without an early dropout (XM-L2 driven using 1s) but they do not use the Zener to power teh QX9920, they do it directly off of battery voltage (not feasible here).