D.I.Y. Illuminated tailcap

The real fun part is when you start playing with 0603 and 0402 components.

I don’t think I’ll ever go for 0402, but I do have a bunch of 0603 LEDs sitting around. The worst part is figuring out polarity on them.

Mine have an arrow on one side. I simply tap the ends with my multimeter on diode test mode and see which way they light up, then I know that the arrow means ground/positive.

I have some questions regarding the bleeder.

1. Does a bleeder drain the batterie when there is not ltc?
2. Is a higher bleeder value better for batterie lifetime or is the lifetime only determined by ltc led current?
3. how can I measure the current drain?

Thank you!

I’ll take a stab at answering, but I could be wrong:

1. No, because a normal tailcap completely breaks the path of electricity flow (using an itc creates a path around the switch)

2. I think this should be negligible, but if you can get away with a higher resistance (say, 1K ohm) that might be better

3. Check to see if your DMM has a mAh setting. If so, remove your tailcap and jumper with a wire and your DMM leads between your flashlight body and tailcap. That’s how I’ve done it at least.

Thank you!

That’s basically all correct. The bleeder doesn’t affect standby drain but is a source of inefficiency when the main emitter is on. You can calculate the loss - V=IR. It’ll be negligible at higher current draw but could make moonlight and other low modes half as efficient or even worse. So yes, use the highest value bleeder you can.

I finally have most of my parts in. Going to first try using the Rev5 base with a Rev5.2 top. If I am going to do 2 different colors then I take it the best config would be 1 color for each channel. I’d like to try using pots, so would it work best for each channel to have its own pot? If that is the case, then I would need to bridge ‘b’ on the top board. Obviously, connect pos and neg on top and bottom. Other than adding the pots to the bottom board, is there anything else I need to cut or bridge for this configuration? Doesn’t seem like it, but checking anyway. Thanks.

First try a success. Can’t tell from the pic, but it has both blue and purple. I used 2 pots which I find very easy to work with. You may notice the pos and neg test leads are reversed. This is because I accidentally reversed the leds. I do have one issue. It’s pretty bright when connected directly to the battery, but once placed in the light the leds dim significantly. The light and modes all seem to work without issue. Does this indicate the need for a bleeder on the driver? Thanks.

Nice, good work.
What driver we are you using?

I tried it on a stock 105c and whatever driver is in the Kronos X6…ATTiny25 FET maybe? Same results on both. The tailcap lights work, but they are just much dimmer.

I believe they will work on a lot of drivers, without a bleeder. However: They tend to influence mode changes, and mode timing, without one. Only you can confirm. I have one using a 105c, and it works fine. Others have had to add a bleeder for timing issues.

The resistors that measure voltage for low voltage protection bleed some current themselves. On drivers that do not use an Off-time capacitor to do mode changes (like the 105c), that might be enough to work without an extra bleeder.

The Kronos X6 drivers from BG come with a bleeder pre-installed since the groupbuy lights had basic illuminated tails from the factory.

Yes I can confirm it. With Astrolux S41S and LEDs on tailcap, you are not able to switch back the modes without bleeder resistor.

Thanks for the replies. Ok, so the modes work fine. I was able to lower the resistance on the blue channel and brighten them up. I think it’s just the purple leds that may not get any brighter. Going to switch those out with a different color.

My suspicion is that there is an effect from the led side too: you are more likely to get a messed-up UI when the new low-voltage leds (219BV1, 219C, XP-G3, 3rdgen.OslonSquare) are used, or triples/quads. A lighted tail in the combination: a lowvoltageledtriple/quad, is really hopeless, I have not managed to get that working in any mod.

I have used purple leds too (very appropriate: in a UV-light), and they are just very dim, not much you can do about it: 400nm is the very edge of the visible spectrum, the output is there but you will not see it, the same radiometric output in green would appear 100 times as bright.

Now I can’t stop doing this, and I’m gonna have to place another order to that Osh Kosh or whatever place.

Looks good Willy. :+1:

Hello everyone. I’ve just read this entire thread and signed up just so I could ask one question… Anyone have any spare parts they want to sell? I have 2 BLF A6’s and I’m interested in a couple clear tailcaps, 2 6 led boards (17mm dumb) and a few leds (red and blue) to populate them. I’m trying to avoid buying 5 tailcaps and hundreds of leds that I won’t need. I’m in the US and have PayPal if someone has spares they would like to part with.