I built 2 of these using a single 3mm rgb led i pulled from an rc helicopter. One for a DD and one for a 105c, neither one needed the resistor on the driver or had any change in the memory function. I tried the resistor on the BLF DD and that caused the mode memory to fail. I am just using the standard switch pcb with a resistor in series with the led. So its wired like this: spring pad - resistor - led - outer ring. the spring side is the - connection for the led.
So after some sleep I’m back to troubleshooting. I’ve got another board with all the vias filled with solder, and tested the resistance of every part of the circuit path and everything is fine with the board as far as I can tell. I’m going to put 2 greens on it at 1k and compare to the 2 red 1k brightness. Pictures soon.
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