I can not find the red/blue C01 via the store either. Here’s the link though:
https://www.aliexpress.com/item/Sofirn-C01-BLF-Special-Mini-LED-Flashlight-AAA-High-94-CRI-Yuji-LED-keychain-Flashlight-Hat/32967363356.html
I noticed that the 5600 no longer indicates high cri in the description. Does anyone know if they’re still shipping with a high cri emitter in both?
Djozz, if you are still in contact with Barry, you might let him know a recent recipient reported unhardened potting again:
https://old.reddit.com/r/flashlight/comments/adtwy0/sofirn_c01_leaks_white_tacky_stuff_potting/
Hopefully this is limited to a small number. Maybe individual assembly workers aren’t mixing the compound consistently.
I had no contact with Barry the last few weeks, but I will write him an email and mention this too. If he had made a picture of the driver I could see if he was sold one of the batch of prototypes that Sofirn made, the driver in those is a bit different.
Too late for that. Tint shift, PWM, ALow CRI…. gross :confounded: . I have been enlightened, since joining this forum . Both Yuji are very nice.
Checking in after my Christmas holiday ‘retraite’: great to read the blue and red versions are available.
I added the blue/red order link to the opening post; and then ordered one of each myself.
Still waiting for the manual price adjustment by Sofirn…
For those wondering about runtimes with Lithium primaries (“L92”): these are great. A discarded because “empty” Energizer lithium with an open circuit voltage (OCV) of 1.61V still lit up my 3200K C01 for 23 hours until completely dark, although most of the time in moonlight mode. Energizer states: “Any battery with an OCV less than 1.70 (after it has been allowed to recover) is completely discharged.” So that is a still 20+ hours of useable runtime from a “completely discharged” cell. 
When taking the lithium cell out of the C01 it read 0.198V, and after recovering for 48 hours it bounced back and stabilized at 0.417V. So I guess now it is really empty. 
One footnote about running the C01 on “empty” cells: it is good to know that the C01 needs a battery with a minimum voltage of approximately 0.87 Volt or so (depending on voltage sag of the cell under load) for the driver to start up. You can measure the so-called “open circuit voltage” of a cell with a digital multimeter (DMM).
Once the C01 is running, the LED just keeps converting electrons in photons with much lower voltages (down to an OCV of 0.2-0.3 Volt), although the output is just much less bright (“moonlight mode”). This means that once you turn off your C01 and the cell voltage has decreased below 0.8V or so, the C01 will not light up again. However, with alkaline cells if you let the cells rest, the voltage of the cells will slowly rise up again. With alkaline cells you can even see this happing when measuring with a DMM. So, wait and after a while you can then turn on your C01 again. No need to keep it on continuously. The same is also true for lithium primaries to some extend, although it takes much more time for the cells to rise up in voltage again.
Got one of each tint, very happy with both. I agree with everyone’s assessment so far that the cooler tint has a higher output and more defined hotspot but I still prefer using the 3000k version, inside and out. I find the output more than adequate for walking in pitch black at night where I live in the countryside in terms of lighting up the road immediately in front of my feet to avoid potholes and whatever. Also perfect for rooting around indoors at night ( in my own home obviously ) or checking on the kids while they’re sleeping without waking them up. The clips were made of cheese however I always consider clips disposable anyway.
As it was originally intended to be, it has succeeded very well in my opinion. A robust, low output, back to basics, single cell, long run time last resort light. Keep one in your car, one on your keys and one in your home and you will never be stuck for light.
Thanks to all involved for making it happen, it’s a very worthy replacement to my Fenix E01 which I keep on my keys for old times sake!!
I should be quick to add that although the clip is pretty poor, if you carefully remove it and switch it around, the light works very well clipped to the peak of a baseball cap, especially for close up work.
My C01s arrived over Christmas. The C01 is a really nice design - well done to all involved!
2× Black C01, 5600K, first batch, ordered 11 Nov 2018:
- good clips.
- solid potting.
- really nice lights.
2× Black C01, 3200K, second batch, ordered 01 Dec 2018:
- clips are useless, no springiness at all, ended up bent like a banana. I threw those clips in the bin.
- potting compound is not quite fully cured. When I gently poke the blunt end of a sewing needle into the injection hole in the PCB, there’s a slight tackiness when I pull the needle out again. There was no such tackiness with my first batch lights. It’s not the chewing gum the prototype C01s had, though - I think iamlucky13 is right, individual workers aren’t mixing the potting compound properly.
- really nice lights in all other respects.
I’ve just ordered a red 3200K and a blue 5600K; hopefully Sofirn have their quality control ironed out now.
Nice, sounds like a great battery vampire light.
I suppose I need to be careful not to over discharge nimh?
Yes.
I guess people should also be careful when draining alkalines every last drop, those suckers might leak.
Sorry to be picking in this photo again:
Yesterday I noticed that the light on the right is the 5700K and in the left the 3200K.
I became intrigued, once that when I normally put lower temperature LEDs (ex: 6500K) under the UV they become more “yellowish”, and Higher temperature (ex: 4000K) more “orangish”.
These Yuji leds seem to behave differently in those “under UV” conditions.
Can some one explain why, please? This is not important, just a curiosity!
I received my 2 C01’s from AE in about a month (ordered early Dec, arrive early Jan). I ordered 2 3200K…but the 5700K were in the box. Other than not being the right tint, (one clip was less rigid than the other), the product looks good. I thought I would loathe the 5700K tint more than I do…surprisingly.
I still want a 3200K or two, but after incorrect processing and seemingly above some 3200K having un-cured potting…. I am hesitant to reorder.
The processing was just a mistake & I don’t think the uncured potting is just related to the 3200K, it is random.
Don’t reorder just yet, contact Sofirn and tell them they sent the wrong lights, see what they’ll do for you.
typo alert: 6500k is higher than 4000k
Im suprised your 3200k is not orange under UV
I cant test my C01’s because I gave them away
In other lights, my UV tests have been between Low CRI, and High CRI
The high cri glows orange, the low CRI does not
I think it is because of the extra phosphor coating that produces the red spectrum in High CRI
l-r N219b 4000k high CRi, XM-L 4000k low cri, 5500k XP-G3 High CRI
I also noted, though that photo is not ideal, that the N219b is more orange than the XP-G3
color charts from maukka show the N219b has higher R9 CRI (red output) than the XP-G3
here is l-r N219b 4500k 9080 high cri, 6000k SSC P4 low cri
.
My only guess as to why the 3200k Yuji is less orange under UV, is because it has different phosphor
the 3200 does have lower R9 in maukkas tests
but, I am very surprised your 3200 does not look like it has any Orange at all, under UV
I think it would be good if someone else tests their 3200 and 5600k under UV… I will do it when my red and blue ones arrive, in about a month 
.
@slowtechstef
This is the best explanation of vampire mode I have every seen. It is very complete and covers a lot of details regarding draining primary batteries in moonlight mode
can you share the voltage at which the C01 can no longer operate at normal brightness… iow, at what voltage does it drop to moonlight mode?
I ask so that people who use Eneloops, can determine if the C01 will overdischarge the battery when operating at normal brightness. My hope is that an Eneloop user can be confident that the C01 will not overdischarge, unless they let it run on moonlight mode.
imo, vampire moonlight mode is ONLY for primaries that will be discarded at the end of the run. I do not recommend running the C01 in moonlight mode with Eneloops.
I also usually remove clips, unless I plan to use the light for more than a few minutes on a hat. Otherwise, I just tuck the light under the had, no clip required.
I can not explain why, but I can confirm your observation (quick and dirty)
5600K on the left, 3200K on the right
Sofirn built good lights, it was AE’s fault in sending the wrong ones. I already worked out a refund of sorts with AE who handled it very quickly and professionally.
I guess I am a little gun shy that’s all, first time dealing with ordering outside of North America.
I have a modded Minimag with a Yuji in it, when I show it alone, its 3200K tint is so nice on the eyes and perfect. If I take that away and look at the Sofirn C01’s 5700K on its own and it looks bright and clear with great color rendition and my eyes forget about the 3200K tint for reference. When I bring it back though…I start the process all over again…lol.
Any suggestions for trit sources?