I think all this troubleshooting can finally be done. The red LED’s simply aren’t as bright as the green (and possibly others). The green LED’s are pulling 1.8mA in this picture using a 1k resistor. The reds are pulling 2.4mA using a 1k(difference due to forward voltage I believe). The green is obviously significantly brighter on less current.
Blue and green appear to have similar output at the same currents. I think the forward voltage of the LED’s is to blame for the difference. Red (Vf = 1.8-2.2v) requires 3-4x the current for equivalent brightness to the LED’s with a Vf of 3-3.2v, by calibrated eyeball lumen measuring device. (aka, perceived brightness)
The blue sounds perfect! I’m sorry you aren’t pleased as this is exactly what I intend to do.
I’m beginning to think we are getting different numbers because your customers want them brighter than I do. This a dual green (560/2.2k) I just built today in my S6 (took a lot to fit it in an S6 btw). After the picture, I changed the resistor because it was a little brighter than I wanted.
Interesting info! I'm still waiting for my boards and some parts as well. Thanks for posting! I'll go for blue and maybe I will green too.
Really any color is fine for low output levels from what I’m seeing. It’s when you want it bright enough to see in a well lit room where the differences come into play in a big way.
Blue and green seem to be the most efficient, and honestly I’m not shocked I guess. In addition to the fact that I think the Vf is at play, I don’t see many high output red LED’s in flashlights either. I think the material that filters the light into red from the LED has a big effect on output. This is why high CRI LED’s are generally lower in output than their low CRI equivalents. Blue has the advantage of needing less filtering and we perceive it to be brighter than red for the same lux value. Green is the same way, less filtering than red and higher perceived brightness for the same lux.
Add all these little things together and you have a red LED that is hard to get big brightness from when you compare it to green or blue.
Only white leds use a phosphor layer (and odd leds like pink). Colored leds produce their color directly, no phosphor layer or filtering.
Green is perceived as as brighter to our eyes.
That’s good to know. I guess half my theory wasn’t worth the words used to type it out. It does appear that blue has a slight perception advantage over red possibly, and obviously green has a huge one.
Maybe I’m the only person still doing these, but I’ll share anyways.
I finally got around to making a smaller version (17mm) of the dual-led board. This will fit lights like the Convoy S series and many others.
Please note I just ordered this myself so it’s technically untested, although it’s essentially the same as the larger board. Also added to OP.
Thanks! I haven’t done it yet, but it’s on my “to do, if I ever get a chance to stop and breathe” list.
Thanks, Pilotdog.
I am finding this board interesting. Could someone tell me what the prices are for the boards, I do not have an account.
I am also wondering how much cutting and such is needed on the S2+ and on the Solarforce lights for install. Or, does enough make it around the switch to get a glow?
Board price is $2-2.50 for 3 boards, free shipping.
I did no cutting to any of the hosts.
I still want to do these, and I ordered the boards a few months ago, but they never arrived 
. I will have another go with these now :-)
Edit: ordered, thanks for the update pd68!
Are these boards on RBD's Oshpark thread? If not it would be good to get RBD to add a link there in his OP. I'm going to order a few just for the smaller diameter. Thanks.
I have my parts coming in for a couple of these switches. It looks like a fun project!
I’ve never soldered SMD’s before, so that will be a challenge.
Already an update, the resistors and switches came in from Fastech. Oshpark should be shipping my boards by early next week.
I’m sure I will have questions, if you peoples don’t mind.
My boards just showed up. I'm just waiting on the SMD LEDs now.
Hmm, I can't seem to insert any images today. Will try again soon.
Edit: I think I figured it out.
Good deal
Long ago I ordered these boards before but they never arrived. A few weeks ago I ordered them again few days ago they arrived.
First try on a Supfire S1, I first took out the stock switch which is a different design, I had to add a ring in between the new switch and silicon cover, had to do that anyway because it was to be white plastic for the red led-light to get through, the tailcap was replaced by a transparant one, the pillar was shortened. The brass switch retaining ring is very thick in the Supfire S1, so I had to ream the inside quite a bit to get it clear from the center pad of the pd68 switch board. The new switch was this one, started with testing some resistor values, ended up with 5.6KOhm on the switch board, 680 Ohm bleeder on the driver. The new design board allowed two leds in parallel :-)
The careful observer will see that in this picture the leds are the wrong way around, they exploded during testing. Actually during testing I blew six of these tiny leds. That will not happen again because now I now know how to do it right.
For the bleeder resistor I drilled a shallow hole in between the batt+ pad and ground ring, so that the resistor was plane with the surface after soldering.
Neat result :-) . I am going to mod this light further (the head is still stock apart from the bleeder R), but this is a nice start. 4V, 6kOhm is 0.65mA, so a 550mA Efest should last about 34 days. I charge it more often than that so that's ok!
Thanks pd68 for the ideas and board, this is a nice little upgrade and a good excuse to fiddle around without having to start on the big hobby-projects that I dread starting, like the DIY contest entry. :sad:
Perhaps as a small improvement, the solder pads for the switch may better not go all the way to the edge but stop a tiny bit from the edge, then there's no chance for them to short against the side of the tail section