D.I.Y. Illuminated tailcap

Hmm how do you think an rgb led would behave?

If it’s separate IAD ( individually addressable) dies then maybe it would work but then they would be all in one place. 3 - 0805 smd’s 120 degrees apart might be nicer but all you need is one or two voltage settings. I have a bunch of SMD LEDs I bought for a similar project using a quad opamp but my ideas seem to have short expiration dates.

The green and blue led would die off at about the same voltage, but if you place a diode before the blue one the voltage spacing between r g and b may be useful.

Exactly, set them up so that battery decay turns them off one by one.

The voltages for one red/green/blue are about 1.6/2.0/2.5 V for cutoff - if they are all in parallel I would add 1-2 diodes to them in series (+1.2V for two) and you get ~ 2.8/3.2/3.7 V indicator. Or one red in series (+1.6V).

The really useful voltages IMO are ~50% remaining, ~20% remaining, and 'please recharge' . So that would be 3.85V, 3.6V and say 3.0V according to the graph below. You'd have to play around with colour leds and diodes to find out how to get there. I might have a go at that, sounds like fun. And then make a new version of the switch board with a lay-out that accommodates the circuitry, when a small Omten is used it will certainly fit.

(the picture is from battery university, this should be a typical li-ion cell, voltages are resting voltages, not under load)

The 20mm PCB’s were delivered today. They look good, although the slots are not present in these. The extra diameter should still make it possible to use the larger omten 1217.

Build thread for my S8 should be posted later today

Will it be similar for an S3 tailcap? This is mighty cool I’d say! BLF is great for this kind of stuff.

As far as I know the S3 switch assembly is identical to the S8

Here’s another wild idea: what about incorporating a light light sensor that only turns the led on when it senses darkness?

I apologize for being away and not responding to the thread for so long. Pilotdog, the LED’s that I was suggesting are super duper tiny. They give off low light but have a high forward voltage of 3.7 v. The advantage of their size is that you could have more room under your switch cover. You would have to reflow it to the PCB board you are using.

You could easily fit 3 different colors in there for different voltages. That or go for one of those 5050 size RGB LEDs.

I bought some 0603 sized led’s to try as well, but I’ve found the DIP size much easier to work with. The issue is that the retaining ring in the tail would block much of the light from an smd led, whereas the leads of the DIP type allow it to be put on the other side of the retaining ring, right next to the plunger.

Also, the 0603 size is sooo hard to see. I had trouble seeing which side is up and which end is pos or neg. I wish I had at least ordered 0805 instead.

I think the blue locator would be ideal. I have always liked the tritium inserts but find the price of machining discouraging plus the amount of light put out by tritium can only bee seen when very dark. Something just a little brighter would be just the ticket. I think this is really cool, I’m glad your working on it.

Yep, blue is actually what I picked for my first real build. :slight_smile:

The light function is actually working perfectly, I’m just having other issues because the switch I used isn’t as tall as the original switch and the battery tube no longer makes contact. Shouldn’t take too long to fix once I get home.


I never thought about the retaining ring getting in the way. That 0603 size is brutal. You need a good quality magnifying glass and a steady hand. That size gives me fits as my hands just aren’t as steady as they used to be. I hope the 0805s work out. I had thought of something along these lines but couldn’t figure it out. My imagined version of what you are doing would be to have the light blink like a plumm light. On full bright and fade off over a second or two then be off for five seconds. But to do that you would have to squeeze an ATTiny13 or similar in there.

Oh, cool. You have more room in there than was anticipated. Hmmm

Yeah I looked for a pulsing or “heartbeat” led but couldn’t find any. I have some 3mm blinking Leds, but they blink a little fast for my taste. 1khz iirc.

added pics above

There are 3mm colourcycling rgb leds, I almost went for some on ebay, but I think it makes the flashlight looking a bit too cheap

Lol i got some of those too! In all I think I ordered about 20 17 different LED’s for this from lighthouseleds.com. I would have to agree, the RGB would be cool for some people, but it’s not to my taste.

Here is my order confirmation. The ones in post #94 are the 1.8mm blue

If the RGB are addressable then that would work for a battery status indicator.

Regarding the pulsing or plumming, I had been speaking with ToyKeeper about how to go about programming an ATTiny13 or whatever back when I was contemplating something roughly similar and far to complicated. Maybe you could chat her up about any ideas she might have along those lines. I like how it’s coming together.