The There Are No Stupid Questions Thread

Battery question.

Some of my 14500 batteries have a “pronounced” pip at the positive end and some don’t. I know the trick of using a small round magnet to make the pip longer. Is there something different about these batteries internal make-up? Is there any reason that thay are not all made to a standard length?

Thanks

Usually there's

flat top

button top non protected

and then button top protected

I'd suggest a solder blob over a magnet any day .

the thought of a possible loose magnet in a light gives me chills .

you can do a decent solder blob in exactly 6 seconds ...Solves a myriad of length issues ..makes life enjoyable again .:)

Excellent. Thank you Boaz. I feel an enjoyable life coming on.

With my Olight Perun Mini, can I put one of those little magnets on the top and then safely charge it in a normal charger like my 18650s?
Pretty sure I can, just wanted to check…

Has anyone ever made a flashlight out of these 250-315nm UV LED parts, or these 275nm UV LED parts Or have a reference to a list of materials that can be successfully built and used in the 250/275nm range? Mod for a Convoy S2+ would be awesome but I don’t see a reference here or elsewhere.

There are UV-C flashlights out there, but I can’t think of any builds on here (at least off the top of my head). If it’s anything like the ~400nm UV LEDs, then you can expect low power, high forward voltage (indeed, looks to be solid 2S territory on the ones you linked), and bad longevity.

If you’re planning a build, keep them within rated spec, make sure they are cooled well, get a constant current circuit at the correct voltage range, and make sure your optics are transparent to the wavelength you’re using (for example: polycarbonate optics block most of the normal UV light we deal with (back in that ~400nm range).

Oh, and use eye protection. Skin protection, maybe, too? I can’t remember.

For what purpose are you looking into a flashlight at these wavelengths?

Yes, you need proper eye and full body skin protection. I won’t advice you on what is proper (I was never interesting in using UV-C myself) but stress that UV-C is highly harmful.

Just to do it, show off to strangers on the internet or friends. I’d try to build an x-ray flashlight if it was financially feasible, tho I see LEDs seem to bottom out well before x-ray territory. Probably different tech altogether and not a flashlight type of device.

EDIT: There are DIY x-ray machine builds available. Not a flashlight at all, but still feasible if you have some extra cash, time, and no concern for personal safety.

About the feasibility of UVC flashlights?

Why does a 21700 battery exist when a slightly shorter 21650 would fit into existing chargers?

Good question!

Tesla and Panasonic thought it was a good size for their use. That was after using 18650s as other car makers did for many years. And now they’re moving on to the 4680. So yes nothing to do with flashlights or chargers.

The 4680 looks large but maybe it could be an alternative to 4x18650 or 8x18650 torches/flashlights.

If I ran out of Attiny25 MCUs is it possible to use Bistro with clicky tailcap switch on an Attiny85?

Why do people chew applesauce?

slmjim

It’s absolutely possible. You can’t go the other direction with some firmwares because the 13 and 25 have less flash than the 85 so for example anduril doesn’t fit.

I’m not sure what, if anything, you’d need to change, but I’m sure it can be done rather easily.

I don’t get it. That’s a whole i1R or whatever in there, no?

That flashlight should charge.

Your charger must be broken.

It’s not gonna charge. The light’s backwards. The pointy end goes down, and the flat end against the slider.

It’s an Olight, that’s why it isn’t working