Is an illuminated tailcap possible?...... Solved?

This would be much easier with an e-switch based driver, but I was hoping for something I could put in my Convoy S8 or Solarforce hosts.

Is it possible to have a PCB made that would have a small circuit - parallel to the main switch - with a resistor and a 2ma SMD LED that would always be powered?

Would the LED and resistor limit all current to 2ma, or would it allow the driver/main led to draw current as well (thus mothballing this idea)?

This would be used with a translucent tailcap as a locator light, just bright enough to be seen in darkness.

I made a schematic to be more clear, please ignore most of the details as it is just to give a general idea

have you considered just setting a faint moonlight mode (can be around 1.5mA) on the primary LED and leaving it on? That would enable you to find it in total darkness.

I tought about it, but that would require me to cycle through it in normal use, and always set the light down pointed at me.

You would need to run a wire down from battery positive to the tailcap.

ok, just FYI - all of my lights turn on in moon mode as the initial mode, and to set it to moon after usage, I have to hold the reverse clicky pressed for cca 2-3 seconds. I actually have some of them in moon mode 24/7 so they are always easy to locate.

I suppose that’s doable. For 2ma the wire could be tiny, but it would make battery changes a pain.

Lots of bicycle lights have something like this — the switch button is translucent and they have a power level indicator by colored LEDs under it (green, blue, orange, red, flashing red). Dunno how, but it’s doable.

Just thinking out loud. If you run a tiny wire from the driver back to the switch I would pick a host with some extra play around the battery. Tiny wire equals tiny insulation. The last thing you want is to create a dead short in your tube.

I’m not sure I could ever be comfortable with just a wire running back. Maybe find some small tubing to use as conduit. Thinking about the small plastic tube that holds up some R/C cars antenna or something similar.

I don’t think so. If you always want it to be “on” when the light is turned “off”, then make this “moonlight” mode to be your “off” mode. You wouldn’t need another LED, or extra wires, or a true “off” mode in that case. When programming your modes in the firmware, program this one to be sequenced the same way your normal “off” mode would have been. As for pointing it toward you, I don’t think you’d need to, but it would be the same if it was a tail-cap LED.

If I didn’t run a wire, and just did it as I have in the diagram, I assume it would turn on the driver and complete the circuit so the smd led would be lit, and then it would supply equal current to both the led in the tail and the main led, depending on the mode the driver is in and the resistor used. Does that make sense? Or does the Attiny require more amperage than that to turn on?

I would have to look into it to see how hard getting rid of ‘off’ would be. With a tail led, I can just headstand the light on the table and the whole rubber tailcap should glow in all directions, instead of laying it on it’s side pointed towards me.

Tail cap is going to be really hard. Why not just use some glow paint or break down and get the Tritium vials and put one in the tail cap. Just a drill hole and slide in the thing. Glow paint would be easier and could be removed or repainted if necessary.

Hmm that glow paint looks interesting. I didn’t realize it could glow for that long. Have you used that glow paint? do you think it would work if I painted the inside of the translucent tailcap? I’d be worried about it cracking.

This is really just a thought of “can it be done?”

It really isn’t necessary.

If you think it might crack, why not paint it on the solid parts under the translucent tailcap, or even get a GITD tailcap.

yes, my magicshine bike light has it. But the switch is a separate unit with wires going towards it.

the space in the flashlight tube is usually too scarce to run wires in the space between the battery and the tube, and there’s a risk of shorting the wire.

However, protected batteries actually do something similar. The protective circuit is at the minus pole, and there is a thin tin sheet delivering + pole to the protective circuit on the minus pole.

Use gitd o rings on the body, gitd tail caps, glow powder mixed with epoxy filling a groove or a hole, tritium vials, a servant that holds your light for you. I like that last option best.

Why would it be necessary to run a wire from the positive side of the cells down to the switch?

Wouldn't the positive side of the led just connect to the flashlight body and the negative to the bottom of the cell? Any point in a circuit is a point where electrons are flowing. If the driver didn't have enough parasitic leakage, couldn't Pilotdog68 just connect the limiting resistor from some positive point in the driver to ground?

I have more GITD tailcaps than I could ever want, but they only glow for about 20 minutes after the lights go out, and not very brightly at all.

Again, the light in the tailcap isn’t neccessary, I just thought it would be cool if it could be done.

I really don’t want to modify the exterior of the lights.

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Anybody have input on post #9?

I like this train of thought, but would that affect performance of the driver in normal use?

I have used the glow paint. They have the one green rated longer than all the others and it lasts a long time. Depends on how thick it is applied and you don't want to put it where you will be touching it much. I have had some that lasts for a few hours. Also depends on the Mfg. The link I gave seems to have or had, good stuff. I haven't bought in a while now.

I think if you want longevity, I would try tritium vials. The small ones are almost cheap enough to buy and it's not hard to install, if you can drill a place for them, that allows them to be seen. Other than that, the paint is about the next best thing as far as I know.