You can run wires directly from the new PCB to the existing one (I solder mine directly to the legs of the switch)
Does polarity matter or can I use either contact on the switch for the + and - on the ring board?
The switch has no polarity, it can go either way.
But I’m not clear how this is being wired in and polarity does matter with the leds so wait for gchart to answer.
On your switch board, one side will have vias (the holes) on the outer ring. That’s your positive side.
Ohh, I see now. Thanks you guys! Will be building this into a laser so hopefully this works.
There is no reason to be sorry about that.
Probably a stupid question but is there a way to have the lighted tailcap only come on when the lights on?
Not typically, no. Turning on the switch creates a direct path for current to flow through the tail. Between an LED and the switch, the path of least resistance would be the switch and the LED wouldn’t get any/enough current flow.
That could be done with an e-switch light though.
I wanted to have 1 more color for a lighted tailcap. This time I mean it - no more after this! I have all the normal colors (blue, green, white, red, orange) and some other colors (pink, warm white, cool blue). Yellow looks great, but is a bad choice since it’s so inefficient. I’ve tried purple/UV and yellow/green, but also found out they are very inefficient.
So I decided to make my own color. I tried dual colors, like pink on 1 side and green on the other, but I prefer to have just 1 color. I eventually ended up with mixing green and blue to make aqua. Green is the most efficient by far so I wanted to incorporate it, and blue is pretty good too. I actually have 3 different types of blues, so I picked the 1 that created the best color of aqua.
Here’s how I mixed the green and blue. Since green is so efficient, I had to double the resistance (22 Kiloohms + 22 Kiloohms) on the green 0805 SMD LEDs vs the blue. I ended up with 0.15 milliamps at 4.1 volts.
The left picture is the best I can do to show how the aqua looks (middle top) and the right is all of my custom lighted tailcaps (aqua again is middle top).
Looks great! I love me some flashlight bling.
Thanks gchart!
Haha, I have done all the things that you have done too NeutralFan, including fiddling with resistors for finetuning the balances.
To challenge your “no more after this”, on aliexpress, with some searching, you will find 0603 leds of several tints aqua and cyan (I have 480nm, 490nm, 500nm) that are genuine single colour leds (not phosfor- converted) and are fairly efficient so suitable for lighted tails. Also a phosfor-converted aqua can be found (blue led mixed with some green emitting phosfor) that is really efficient.
Thanks for the info djozz! I’ll have to look for those tiny LEDs, but look just for the sake of curiosity. 
I think I’m beating my head into a wall on this, but is there a simple way to get the lighted tailcap visible through the metal S2+ switches? I’m trying to get lights behind a purple host.
Ideally it’d be quite dim, even in pitch black - it’s for my daughter’s bedside table, just so she has a point of reference to grab it. I do want to change the colours though, so I realise there’s probably different resistances needed.
I got some of the lit tailcap boards from Convoy, but they’re nigh-on-invisible through the cap. I tried removing the resistors and just joining the path, and they flash bright momentarily, then go back to exactly the same brightness they were with the resistors on.
If it gets too hard I’m happy to buy something else, but l4p is down, and I (to be honest) haven’t yet checked if Lexel is still doing them.
Did you install a bleed resistor on the driver? Which driver is in the light?
No resistor as I’m not worried about mode changing, and a Biscotti one, 4*7135. Custom mode though (1,2,3,0).
According to this post the current to the tailcap leds is dependent on the number of amc7135’s.
wtf wont my bleeder resistor work? - #3 by Henk4U2.
I would think adding a bleed resistor would allow the leds to get what ever current the bleed resistor would allow. I seen several post talking about the plastic ring around the metal switch being black and wouldn’t let light through. I’m assuming you have a metal switch that’s made to light up with the clear washer and all.
Yep, the rubber around the metal is clear, it lets light through:
And the kit came with a clear washer. Interesting, I would have thought that with no resistor, they’d be brighter given that it’s direct voltage? But an interesting read nonetheless.
If I move the tail pcb over to another light with the Convoy 5A CC driver, it does the exact same, so it’s like the actual LEDs are restricted to this amount of brightness inherently.
It’s just really not that bright…
It’s a matter of just how much current the driver will allow from the positive of the battery to run through it and back down the tube to the switch. The current is running in reverse of normal operation. Thats why a bleed resistor is needed in some lights and some need it for the firmware to behave properly.
I know your going to need more current with the metal switch to get light through than a clear rubber boot switch. For my clear boot lighted tailcap switches I usually use 120k resistors at the leds. Its hardly visible in daylight but at night on my bedside table its easily found. If its too bright (resistor value to low) it looks like a night light shinning on the ceiling and the wife complains 
. 120k and above works good for me and last 1 1/2 years or more with the parasitic drain. If you get the parasitic drain to high the battery could be drained in weeks to a few months.