[1900k edition is in!] WTS: 1900k-5800k 5mm LED 95+ CRI

In any case, driving leds in parallel could have some current sharing problems due to Vf differences between emitters. This can be minimized by binning leds with a multimeter, i.e. set them all extended over a table in a room with stable temperature for a little while first (acclimating emitters, they're sensitive to temperature) while laying a multimeter close, then use the multimeter to read and note down every emitter's Vf systematically at least once. Use the results to sort the emitters in Vf packs: 10 lowest, next 10, …, last and highest Vf 10-pack. This would minimize the above problem.

Well, as a word for caution, Vf disparity will be an issue.

The 3400k/5800k does have 0.1v higher Vf than 2300k.

I will, Barkuti. Thank you guys :slight_smile: .

Will come back with questions when the project advances, I fear :person_facepalming:

No problem. The colors will be driven seperately.

Just an update:

only 5 2 packs left for 2300k.

I will check up with my supplier on Monday and see if I can restock this 2300k tint.

There are many ways to drive emitters. Arrays of series emitters will display closer average Vf sum, this for example means it would be far better to drive a 10-pack in 10S or 2P5S arrangement. Watch out I said 2P5S, this means 2 parallel 5S arrays, which is a lot different than 5S2P. There are cheap boost DC/DC converters which can output that voltage from li-ion cells easily:

The MT3608 boost module is going to be reviewed by Henrik soon I think, sent him a 5 piece pack long ago. Now that I recall this, it was the 5th of August, he should have received the package sometime in September and we're almost in December already.

About that CRI 95 SMD, you mean this one?

Yes

Regarding driving LED’s in parallel, I think we can make some basic deductions from djozz’s data:

If you’re driving 10 at 350mA, that’s 35mA each.

From djozz’s graph, that’s about 2.95V.

If you had one LED in the group with a Vf that was lower and therefore hogging the current, then from the same data, I’d estimate the resulting current in the worst-driven LED as follows:

0.1V lower = 55mA
0.2V lower = 70mA

Since one of his survived an isolated test for 12 hours at 100mA, the over-current does not seem to be a problem. However, rngwn observed that if packed together, they heat up and may eventually run away:

So for the idea of running 10 on a 7135, I think heat is the main concern.

Yes, heat can be a problem in those 3xAAA 20 or more LED lights.
Especially those in the middle of the PCB can get hot on the crappy stock PCB they’re soldered on.
Good idea to epoxy a heat spreading disc on the back.

The LED that’s in those bullets is a 0.5 Watt 5mm LED similar to this:

I bought a copper bullet branded Astrolux (i think TB-01 ?) with pretty powerful 3x LR41 inside plus 3x LR41 spare batteries a few years ago from Banggood.
I estimate it’s around 15 Lumen with fresh batteries, maybe even 20 Lumen.
Pretty impressive for the size.
Those Mateminco branded ones are crazy expensive.
Here’s a stainless steel one:
https://www.aliexpress.com/item/32844630381.html
You can see the brand name is photoshopped away, but i bet it says Astrolux.
Here’s an aluminium one:
https://www.aliexpress.com/item/32839012681.html

Either way, yes it would be nice in high CRI warm white, but Djozz tried it with a Yuji 5mm LED iirc, and it was much much less bright.
These LEDs here will do a better job, but still a lot less than the stock LED.

I think these LEDs are better suited for lights like this:
https://www.aliexpress.com/item/32885217288.html
https://www.aliexpress.com/item/33023962121.html
https://www.aliexpress.com/item/32923872041.html
https://www.aliexpress.com/item/4000385078691.html
https://www.aliexpress.com/item/32775843914.html

PM sent! i am interested in a pack of the 2300K and a pack of the 3400K for mini lantern mods & builds. :smiley:

And with that, the 2300k is out (except one reserved for Skylight)

Will let you know if the supplier got any left.

New list of T/Ns

iamlucky13 - (1x 2300k / 1x 3400k)
candor - (1x 2300k / 1x 5800k)
Agro - (2x 2300k)
nastynate - (1x 2300k)
Jerommel - (1x 2300k / 1x 3400k)
DBSAR - (1x 2300k / 1x 3400k)

Asian8640 - (1x 2300k / 1x 3400k)
mitsuki08 - (1x 2300k / 1x 5800k)
nismo - (2x 2300k)

Djozz - ()
skinny_tie - (1x 2300k / 1x 3400k / 1x 5800k)
nismo - (1x 3400k, 1x 5800k)

Scientist - (1x 2300k)
Buck91 - (1x 3400k)
DBSAR - (4x 3400k / 2x 2300k)
datiLED - (1x 3400k / 1x 5800k)

u/somnambulism (1x 2300k / 1x 3400k / 1x 5800k)
Skylight - (1x 2300k / 2x 3400k / 1x 5800k)
Slayer1 - (1x 2300k)

Note that the LED with the lowest Vf will get hotter than the others. Which will lower its Vf further.
I don’t know if this is the case here but sometimes it spirals out of control.

So I did some more replacing of LEDs, this time in my new Sangean MMR-88 DAB emergency radio. The original LEDs were 3mm 6500K ones, changed them out for the 5mm 2300K LEDs. Had to drill up the reflector but that was pretty easy as it was just plastic. The PCB for the lights were modular and unpluggable, so the job was pretty easy. Overall I think it turned out well, brightness isn’t the greatest obviously, but it was pretty terrible with the original LEDs so it didn’t matter much.

Beam profile and color temperature of the new LEDs, camera @5000K

Unfortunately I don’t have a picture of the old beam profile, but here’s one of the original LEDs. Camera @5000K

The light itself on low brightness. It has four modes; high, low, flashing and SOS. When the radio is off, it’s just high and off unfortunately. Should’ve been low, high and SOS.

Time to change all 5mm LEDs I can find!

So, in conclusion: Current should be chosen below specs, serial circuit would be ok with booster and FET to control current. I guess if those three 10-LED-arrays will do 50lm each or even less, this would be more than enough anyway.

I see if I can use 3mm aluminum sheet and drill some holes.

I have a couple project lights I have run a bunch of the 3400K in parallel.

One is a 36 LED desk lamp with 3S 12P, running each at about 30mA. For this application I want it to be able to run many hours at a time and last for a long time. 30mA should do that. Looking at them with dark sunglasses :sunglasses: They appear to be driven very evenly.

The other light is one of those cheap drugstore 3AAA lights with 6 LEDs. I was able to find room on the board to drive them with a 7135, so that comes to about 58mA each. They get a bit warm after 15 minutes or so but also appear to be driven very evenly, all the same illumination to my eyes. This was a useless junk drawer light until these LED’s were installed. An 18500 fits well in there with a spacer to take up the extra diameter.

Beautiful light quality on both of these; warm floodlight.

Also a special thanks to Djozz for providing the test data on these. I have referred to it many times.

Good news,

My supplier still has a plenty of 2300k left and I’m about to snag 2000 pcs (40 pks equiv.) for 2300k and 3400k each.