D.I.Y. Illuminated tailcap

Wouldn’t it be easier to just have a couple of different colour leds with different resistor values that would turn off when the battery voltage drops below what it will light at? Is that something that is possible with a 2.8-4.2 voltage range, I know that kind of circuit is widely used for 12v batteries, and also certain laptop batteries. Given the different voltages needed with red, green, and blue?

It would take some work but I’m sure it’s possible. I’m not going that route mainly because I think mixing colors under the boot would be kind of ugly.

Also, these led’s are off when the main light is on, so it’s not ideal for monitoring battery voltage.

They would still power on when switching modes, so it would be better then leaving it entirely to the driver for battery monitoring

By all means give it a shot. It’ll be cool to see the different possibilities that get started from this thread.

Finally got the blue one done. I really, really like it.

here is the build thread for the pretty guy on the left

The one I was working on used a quad op amp to turn on the LEDs at different voltages so only one was on at a time but that package is bigger than a 13A so better suited to part of a battery cage.

Just did another one, this time with an 0603 red led. Instead of the usual black plastic or steel washer, I used a 5/16ths white nylon washer. It lets the light through, and as a bonus diffuses it and spreads it along more of the cap. It also saved ALOT of frustration and time versus the dip led’s.

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On the left is the single 0603 under the nylon washer and clear cap. On the right is 2 wide-angle 2mm leds directly under the cap. Both the blue and the red draw the same current in this picture, the blue is too bright to be a bedside light, but the red is just right. In real life the red light is more evenly spread than the picture shows.

Sweet! I like it! Just waiting for my parts to turn up now!

I’m going to try to learn Eagle real quick :wink: to make some alterations to the board that will make it a bit more versatile. (I don’t want to keep pestering Helios, and I’ve wanted to learn Eagle for awhile anyways)

The lit tailcaps look great and you're still in the early stages. Way to go bro.

Best wishes on using Eagle. I just learned to use it enough to design a board recently and it was a challenge for me. Just a lot of info you need to know that isn't in the tutorials and such. Worth learning though IMO.

This is what I am planning to do in Eagle. Before I go through that work, can anyone see any basic flaws in my design?

The resistor and diode are in series, the led’s are in parallel. Alternatively, you could put the first led on the D1 pads so that the LED’s are in series.

Seems plausible. Is the micro switch you searched in the other thread also intended for the lighted tailcap?

I was thinking about it, but I don’t think I found one small enough.

Well, other than getting it to upload to Oshpark correctly, it’s done.

Ok, Oshpark issues are sorted out. 20mm Dual-LED board is in the OP, ready to be ordered.

Great work Pilotdog! How bright do you think a pair of blue 0603’s would be? I’m looking for about twice as bright as a tritium vial.

it depends on the resistor value but with almost any value it will be way brighter.

Ordered all the parts just got to wait for them to turn up and give it a go :slight_smile:

I don’t have any trits, but if use anything lower than 4.7k in the tail, its basically like an always-on moon mode. It’s enough light to walk by in total darkness.

In total darkness if I hold my watch up to a page of a book, I can just barely read it. I definitely can’t navigate by it.

I see at the store you linked to the highest that they have is 2.4k ohm resistors in the 0805 size. I must be missing something.