BLF A6 FET+7135 Light Troubleshooting and Mod thread

Moon runs at half the usual PWM speed, about 9 kHz instead of 19 kHz. It uses a slower setting to improve the stability and reduce voltage sensitivity. And at such a low output level, the 9 kHz tone it makes should be fairly hard to hear.

FET-based modes are louder because there’s a lot more current pulsing. 350mA vs 5000mA, roughly, so it’s like turning the volume up by a factor of 14.

I’m not convinced it will help either. Changing the speed doesn’t guarantee that parts won’t resonate any more. But a different speed should at least change the harmonics and might make the waveforms stop aligning with the hardware’s sweet spots. Then again, it could also make things worse. Depends on the individual host, I suspect.

It’s probably more effective to do as you said, physically alter the connections a bit, and thus change the hardware’s resonant sweet spots.

Technically since we’re playing with unknown resonances of hosts/sprimgs/joints, lowering the pwm a tiny bit might help just as much as raising it.

Oh well.

Just tried the black fabric thing with an A6. It actually works! :smiley:
I can hear it and according to this phone app it is at 13.5 kHz:

Which is also what I measured in the past on an oscilloscope with other firmware running fast PWM with the AtTiny13 at 4.8 MHz.
I know according to the Atmel datasheet it should be 4.8 MHz/256 = 18.75 kHz, but I think we are missing something somewhere. Phase-correct PWM gave 7.2 kHz v.s the 9.4 kHz expected.

Related:
The MCU output signal going to the 7135s on a 105C is not pretty with high frequency PWM. These chips were never designed to switch at 20 kHz. This is why PWM < 5/255 is not stable with high frequency PWM. The signal needs that 5/255 time just to stabilize. You also need to add about 9 to the PWM level to get the expected current with fast PWM, e.g. 73 vs. 64 for 25% current.

So I tried a 9.6 MHz/8 MCU clock with phase correct PWM. This gives a PWM clock of 2.35 kHz according to the datasheet. I measured 2.22 kHz, so much closer to the calculated value than with the 13.5 vs. 18.75 kHz above. I can see the PWM when flicking a business card, and it is slightly audible, but it is not bad. Moon mode can go very low and is much more stable with dropping voltage. I like the trace much better on the oscilloscope, and 64/255 actually gives 25% current. Will have to try it in a light to see if it is acceptable.

I have a somewhat off-topic question: Why are the threads at the tail end of the battery tube anodized on this light? I know that it allows lockout, but why would you need/want lockout capability for a light with a mechanical switch?

I’m wondering if the unanodized version of this light, when it’s available, will have less problems :)…

Jim

About buried stuff: I can find the output and currents of the BLF-A6 firmware (like above in the OP) but can not find back how in each mode the current is cleverly divided between FET and 7135, and what frequencies are used. Where can I find that again, or can someone repost it?

I personally haven’t been locking mine out but I can see since I am using the pocket clip for edc how you could switch it on trying to put it away.

I think the anodized threads fall along the lines of trying to please as many people as possible.

Two more reasons to anodise the threads: 1) it is easier in the manufacturing process, you can do the anodising at the end instead of halfway before machining the threads and extra risking damage of the ano, 2) anodised threads are way more wear-resistant than bare aluminium.

The best compromise is the threads on the head side not anodised for maximum electrical contact, and on the tail side anodised against wear from swapping batteries, and possibility of lock-out.

Looks like I'm having some common 7135 issues. I'm trying to get at the driver and I get this brass retainer ring off. I've tried turning it with quite a bit off force and no joy. Should I try gentle heat or is there some other trick?

Try a drop of penetrating oil (“nano-oil” works well for me — ’oogle it for more, it’s debated among watchmakers, gunsmiths, and other users of moving parts)
and/or a drop of tuner cleaner/electronics cleaner/lubricant (I have an aerosol can from somewhere)

Don’t pour the oil in and don’t spray the lube in directly.

Just take a drop, smallest possible amount, put it in on the end of a toothpick, and draw the tip all the way around the circle wetting it where it can work its way into the threads.
Then put it so gravity works for you and leave it overnight.

Wipe out the threads with something that won’t leave more stuff in the threads where they’re rough — microfiber cloth maybe.
Look hard for any little ‘boulders’ of swarf sitting and jamming the thread where the ring needs to turn.

Wiggle the ring gently with the needlenose pliers.
Wipe and maybe oil/lube one more drop, no more.

Why all this? Guessing/speculating these were assembled without being cleaned and/or in a dirty environment, so it’s possible any sort of stuff is down in the threads in small sized bits.
Anything from metal filings to, well, anything. So you may be trying to dissolve something, or dislodge something.

This is basically how I got the stuck head off my light.

I’m not intending to argue (but I guess I am), but it seems like the problems that some (a lot?) are having with lights not working because of slightly different tube dimensions because the threads are anodized are way worse than the positives mentioned? The button is not stick out of the rear, so it seems like it’d take some effort to turn it on accidentally when in pocket especially with the clip?

In my case, I lucked out and my light seems to work ok, but if the end of the tube was just slightly too short and prevented the contact to the retaining ring, then… no light…

I can’t find it either. TK’s firmware links may tell. But she will know for sure what. I think 1-4 use the 7135+ pwm, then just pwm 5 6, fet dd for 7.

Thank for that, makes sense. I’ll put a few drops on and leave it a few days for the oil the penetrate.

Anything volatile is going to evaporate and deposit further inside the light.
LED emitters are known susceptible to contamination from anything volatile — that’s why there’s sealant over the emitter, but it’s not a perfect protection.
Anything — temperature control gunk, O-rings, solder/flux, cruft, penetrating oil — is going to volatilize to some extent.
The reflectors are really not easy to clean without scratching; if your light’s bezel/head is removable (with all the precautions about pressing on the glass while rotating the bezel, being careful not to dedome the emitter) then you might take the reflector away first and leave the LED open to the air (sit the thing on an open grid/mesh)

One drop of whatever, with that drop led around the groove with a toothpick, and let it work its way in.

Don’t mind me, I’m just nitpickery about this stuff.

Pics added! function check, tools, spring bypass, sanded star. Member vinte77 found an awesome pocket clip of you’re into that sort of thing :wink: check in the opening list for a link.

@dudunphy, what a great thread you have started! Your OP is full of useful, and informative information. It has also prompted some of the brightest forum members to add their helpful input. This thread, in my opinion, gets right to the heart of what BLF is all about.
Thanks for your contribution!

Thanks scotlarock! This light deserves it and looks like more of these drivers will be getting used so I hope it is helpful for a long long time. :smiley:

Hi didunphy, the driver spring bypass you show in the OP is kind of tricky because with the bare wire used and the retaining ring in place, if the wire is not positioned perfectly, there's a chance of shortage against the ring and that is a direct battery short. Using silicone wire makes it less critical even tough it still must be done with care.

Someone had a link to a tir lens from fasttech that fit the a6. That might be nice to add to OP.

You’re right djozz. I wish I had ordered some of that with my last shipment. I will take that down until I can get a pic of a safer method.

And I’ll get that tir link as well. Thanks!