22 Ohms would do just fine. With fresh cell, it will drive the emitter at 45mA and less as the battery are being used up. Still, if you can afford to do it, a buck converter or at least a linear regulator is recommended to keep the LED drive current constant.
Thanks, I’m a complete noob with all this. I’m going to get some C01s to play with, but I also have some old 2AA minimag hosts, and some plastic AA dummy cells that would take a resistor soldered across the inside really easily.
Unless you can suggest any kind of buck converter with a diameter less than 14mm that I could just put in series? Maximum simplicity is the idea here…
Sure, for the low currents that 5mm leds need, a resistor in series is a perfect way to regulate the current (for high power leds you needs more fancy ways of regulation if you want to maintain more or less constant output). 150 Ohm seems rather high, but you can experiment, you may end up with 10 Ohms or less.
I’ll bet they can be safely used direct drive on two Eneloop or any 2 NiMH or NiCad cells, or two primary 1.5V cells of choice, like button cells or alkaline (but not 2 Energizer Lithium), also probably fine direct drive with a single primary CR123A or any size 3V primary.
Just got mine today, 3400k and 4500k. Ordinary shipping took 13 days to the UK. Well packaged, ESD bags. All good.
PM sent
So far I have had not trouble using Yuji 5mm LED’s direct driven from 2 x AA alkalines or 1 x CR2032 lithium coin cells.
rngwn’s LED’s are even more robust than the Yuji’s, and I also have several of them in 3xLR44 button cell lights.
Voltage drop under load for all of these options seems to keep the output pretty reasonable.
Who is the manufacturer of “rngwn’s LED’s?” If they have been named, I missed it. It doesn’t matter to me, but it would be easier to refer to them with the name of the manufacturer, rather than, “these LEDs” and “those LEDs rngwn found” or some arcane code that is effectively meaningless because no one knows what it means. One thing Yuji really has going for it…. easy as hell to know what someone is talking about when they mention “Yuji.” Just a thought.
It’s likely Sophia. But since rngwn found them, have djozz tested them, stocked them and gave them a good naming scheme, I’ll stick to the terms he coined.
This 2$ keychain would be nice for these 5mm Leds if only mounted a real battery and circuit board,
also solar panel is not connect on board according reviews.
And why 3 Leds?
A coin cell and contacts welded to it is utter crap imo. Probably no rechargable battery (3V) due to cost, so the panel wasn’t connected.
Maybe there is a good one? Idea was not bad
This 2014… have panel connected but still not circuit and you have to press hold button on,boring
I
Yeah, that’s probably a working unit. But I trust the customer who took that light apart, uncovering the sad truth. It’s fake all over, not worth of rngwns fine LEDs.
Group photo
L-R: 5800K, 5000K, 4500K, 3400K, 3200K(120mA), 2300K
This one is oposite grouping but you already noticed that
Nice collection, id 30209!
Resistor bypass on the 120mA unit?
Yup
Very nice id30209.
Anyone know if the C01 3400K is the same as these or different bin?
Update: 32K-C-EX (3200K 0.5w) is now available in a bigger pack of 50pcs, $19.95/pack.
They’re spectecular in the C01 especially with the resistor mod 
Shipping fees table updated.
Ordinary shipping option is now available for $1 less.
Check for updated destination countries here:
https://drive.google.com/file/d/1OGkBLRXkgaOuA-x2N-I2fLe0faBrUXeu/view