The There Are No Stupid Questions Thread

im selling something i bought on amazon in a second hand market, the buyer is asking for the gift receipt. is there anything i should be concerned about? like is there anything they can do with the gift receipt that can be linked back to me in a negative way?

You may get some thicker PCB and file them down to the desired thickness.
It’s a bit painful with copper, so for people who have them I’d recommend some Virence / Led4Power alu PCBs. These are hard to get nowadays though…

It never produced much heat so I figured it wasn’t being worked hard.

According to the description on Banggood:

  • LG UV365nm LED 5W lamp beads are used.
  • The built-in drive is 7135x5 single file.

As far as I know, about the best they can do is attempt to return it to amazon for the original purchase price.

That said - in the secondhand market, if people want weird things, I usually just consider that it’s either too much trouble, they’re up to something, or both. Hopefully for you it’s an option to just move on to a less suspicious buyer.

Sorry, I thought you were saying you had two different lights.

Appreciate you trying to help. I have three in total: the S2 UV, an S2+ with 7135*8 driver and T6-4C XML2, and an S2+ with (if memory serves) a 7135*6 driver and a U2-1A XML2.

Xml2 leds can handle up to about 8A. So you can swap the driver on them for sure.

The UV leds are not robust at all. They can not handle high amperage. So I would not swap their driver.

Maybe somebody that knows what specific LED is used can give us some numbers as to how much power it can handle. My guess is no more than 2A.

I’m not sure on the current handling, but if you search around BLF some you’ll find that all the UV LEDs can’t handle much heat, either. Even treated nicely they don’t have great runtime ratings. You can probably run them at 3A briefly and get lots of power - but, at least for all the examples I’ve looked at, you’re also going to need a 2 cells+buck driver or one cell and a boost driver to hit much current on them - the forward voltage starts high and ascends rapidly.

Wouls someone please tell me how to post an animated gif for one’s avater? Doh

I’m going to guess that you first need an animated gif that is no larger than 85 by 85 pixels. Then try to upload it in your account settings.

Yes, and your avatar must also be under 30 kilobytes.

Thanks to Jason and Scallywag for their input on UV LEDs (I left it as is).

I just recieved an Emisar D4v2 with 3500k E21A emitters, I was wondering if it’s “normal” for them to immediately turn blue on turbo with a high drain battery?
I’m assuming that it has the Noctigon driver which delivers 5A on turbo.

No, that is definitely not normal. I wonder if your driver wasn’t correctly flashed with the NoFET firmware.

The LEDs are already burned, I think I’ll send them an email.

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?