D.I.Y. Illuminated tailcap

You mean how much current is bypassing the driver? I think it’s easier to just “do the math” based on voltage and resistance. To actually measure you’d have to isolate it somehow, or disable the mcu so it doesn’t turn on when you bridge the tail with a meter.

Maybe someone else knows how to predict it or something, but I use trial and error. Try a 680ohm first, and if that is still acting funny start going down from there. 680ohm, 560ohm, etc

Thanks for the quick reply.
I would if I could… but I just don’t have many SMD resistors laying around. I need to get me a value-pack :smiley:

Higher resistance is better for efficiency when the light is on, but lower resistance is more likely to restore driver function.

Small update on the plan above - we have light! The host, LED, driver, and optic worked out perfectly. Unfortunately, I’ve ran into a couple of snags on the lit tailcap.

It turns out, the S2+ tailcap with rubber boot cannot be swapped out onto the S2+ with metal tailcap boot, the tailcap design is different. So, you can’t end up with a rubber tailcap S2+ in any other color except for black and gray (only two colors made with both rubber and metal tailcap). As such, I’ve decided the best way to go is to use the washer ring led on the red S2+ I have – a new project!!!

As for outfitting the gray S2+ rubber tailcap, it seems I should have gone with a 16mm LED board to match the original tail switch size as the 17mm PCB will not fit in the brass retaining ring, or is there another way?

Where would I place the bleed on a stock S2+?

I also built one with a rev 5.1 board with 1k ohm resisters in a triple xpl with a FET MTN-17DDm driver (without a bleeder), but the LEDs do not appear as bright as the ones shown in this thread.

You probably don’t need one

I tried without a bleeder but the tail cap nor the light will turn on.

I’ve built a bunch of S2+ lights but I’ve never bought one already working, so I’m not sure what driver comes in that light. But if its got 7135s on the bottom of the driver near the positive spring, just drop a resistor between that positive spring and the center pin on a 7135 (they’re all connected to ground). Just be careful not to short anything.

Here’s a photo of one I did:

Thanks PD! I think I will build a board without mcu to test it or maybe erase the mcu on a complete driver.

This may be helpful for those who don’t have the proper 2mm thick material around to make a clear washer. I discovered that the 3/4” washers with 5/16” holes are exactly what is used in tattoo machines, here are some on eBay in clear acrylic . They also come in frosted clear acrylic and various other colors :).

will it be available separately, that we can update existing hosts?

:blush: thanks

I spent a couple hours playing with different LEDs and resistor values with very little success, basically, if you try to use different LED colors with much different Vf then the light output will vary significantly between them over the operating range of 3.7-4.2V. No combination of resistors for blue and red LEDs produced a consistent light output from each LED. Best results are obtained by using all LEDs of the same color (really more same Vf = forward voltage) IME YMMV.

If I had the Rev3 PCB and I want to use the Rev5b LED ring…where on the Rev3 PCB should I connect the positive and negative leads from the Rev5b LED ring?

I feel really stupid asking this question. :blush:

Don’t feel stupid. The answer is - anywhere you can find the power. To be more specific, I’ve been tapping all my Rev5 ring boards directly to the switch itself, one lead on each side. One side of the switch is always connected to the battery’s negative and the other one is always connected to the body of the flashlight. Press the switch and the circuit is completed. I think the fact that one side of the switch is always connected to negative is pretty obvious. What may not be immediately obvious is that from this point in the flashlight circuit the body of the light, which we normally think of as ground, is actually connected to the positive “bleed” from the driver. You’ll have to do a bit of testing to figure out which side of the switch is which.

I’ve ran into an unexpected glitch with the S2+ build and the offtime based STAR_1mode firmware when using the lit tailcap. The driver will operate correctly when a battery is first inserted, but if I return and try some minutes later the light will not turn on unless I remove and replace the battery.

If I change to a standard (not LED lit) tail the driver operates perfectly all the time, so it has something to do with the lit tail. Any suggestions on what the issue may be or how to resolve? Will this still require a bleed resistor possibly?

The only changes I made to STAR_1mode were to reduce #define LVP_MIN from 7 to 6, uncomment #define MODE_LOW, and comment //#define MODE_TURBO. Here for reference in case it’s at all helpful now or to anyone in the future :):
https://www.dropbox.com/s/ozgfqq3ejh8lnit/STAR_1mode%20Single%20Low%20Mode.7z?dl=0

Ist this the correct circuit for rev3 board?

Thanks!

By default yes, but there are extra traces so you can split the two sides of the board and have a different resistor value for each LED

edit: technically the order of the circuit (where the button is) is flipped around in your drawing, but it doesn’t matter for what I think the root of your question was