D.I.Y. Illuminated tailcap

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pyro1son
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pilotdog68 wrote:
if you need a whole bunch, check these out

I may need to order some of these! I’ll look into it later this week. I will probably have some left over to shift Smile

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pilotdog68 wrote:
Now you have me thinking about different spacers. I wonder if using colored acrylic would help spread the light/color better than the frosted nylon I was using originally?

!{width:50%}http://i.imgur.com/MNUiar0.png!


I would skip colored ones. Even, say a red ring with a red led, they may actually slightly reduce the light. Filters create color by subtracting other colors. If it is anything less then 100% transmission of the led wavelength then it will reduce the light. With filters to get a particular shade of red (or any color) it may cut some wavelengths of red to less then 100%. With clear you can see it’s as near to 100% as possible across the whole spectrum. And colored non-frosted filters won’t provide diffusion.
For adjusting the diffusion of a clear ring you can sand the surface. I would also paint the switch body and side walls white. Perhaps reflective metal foil tape if you have some.
pyro1son
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Judged moved my first led tail cap to a solarforce containing this driver and it lights up with out a bleeder resistor. I see what was ment by some drivers having their own leakage.

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pilotdog68
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I just tried purple led’s and im a little bummed. According to the Vf rating, they should work just like the blue ones do, but no such luck. They don’t produce enough usable light until they get over 3.8v

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Kloepper Knife Works
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Has anyone tried this mod on a light with a Q.lite rev A driver with mode memory and an off time cap? I just noticed that this mod appears to make the light next mode memory, I assume because the cap can never discharge. Am I on the right track? If so, do we have any other options, or will this effect be present on any driver that has off-time mode memory?

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Did you solder a resistor across the driver? (560 ohm or so , from + to - )

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Yup, that’s why I’m thinking it’s the off-time cap being affected.

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Just checked, it turns a BLF17DD into next mode memory too.

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Try a lower resistance on the driver.

I was having the same problem, but 560ohm worked for me. You may have to go lower though.

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

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You mean a higher value? It’s using a 560 ohm currently.

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No, lower value.

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

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Does that cause the caps to drain faster then? Just trying to understand what’s at play causing it.

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I’m driving so I can’t really explain right now. Have a look at the original thread linked in the op.

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

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Will do, it must be something I forgot reading from the first time I looked through it. Thanks for the help, drive safe.

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Odd... seems like there is still too much voltage drop across the driver. What values are you using for the resistors and what color LED (forward voltage drop)? Is there a diode in series with the LED (if not try adding one)?

Maybe try using an Off Time resistor (across the OTC)? This may alter the OTC values in firmware...

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2 red LED’s with a 1.8-2.2 Vf, 1k limiting resistor, 560 ohm across driver, bridged diode pads on board for 3rd spot

2 LED version of the board

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Your comment about voltage drop across the driver just rattled something loose in my brain. A lower value resistor on the driver will drop more voltage, which probably let’s the driver see a voltage too low to run. When the value is too high it’s sees a voltage too close to its operating voltage, so the driver memory must never set.

That is my educated guess without following Pilotdog68’s advice and re-reading the other thread yet(which I will do).

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Hmm something seems off. Those red leds should be much brighter with only a 1k.

Your theory lines up with my own. I don’t think the issue is just the OTC not draining, I think it the entire driver is getting enough power to stay awake, so memory never sets in. (I’m pretty sure that’s what you said)

I don’t know all the electrical lingo and my circuit understanding is still pretty basic, so I’m just going off what I observed. The test with the blinking LED revealed a lot.

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

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Are the LED’s in series or parallel on the dual LED board? I’ll test the current draw with my DMM, but it wasn’t even registering 1mA on my power supply.

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The LED’s are parallel to each other, and in series with both D1 and R1.

I was reading through the other thread just now, and post #86 is a good one to start at. That’s what I believe is happening to you, but a lower resistor on the driver should remedy it.

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

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Pilotdog68 = my hero

Thanks for the help, I’ll update once I get it all sorted out.

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Results are in. Modes work again. Here was what I did.

1) changed current limiting resistor to 470 ohms to increase brightness as requested by slow2go
2) changed to a 330 ohm resistor on the driver, no mode memory
2) added a 1N4148 diode to the board to see if I could reduce leakage to the driver, no change
3) dropped resistor value on driver to 100 ohms, MODES WORK, draws 2.9mA
4) dropped resistor value to 220 ohms for current limiting resistor to further increase brightness, mode memory stopped working
5) changed the resistor on the driver to 51 ohms, works properly again.

Based on my findings I think the ratio will need to be about 5 to 1 for the resistors (limiting resistor on board about 5x the value of the one on the driver).

I love a good challenge.

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Well I’m glad you got it working, but I’m puzzled why you need that low of values for the led’s to be bright enough. Where did you get these red led’s? It sounds like they are very inefficient. On both of the red ones I have made, I used 560ohm on the driver and 4.7k in the tail and it was bright enough to be clearly seen in a well-lit room. I had to switch to a 6.8k in the tail to make it suitable for bedside use. 3ma draw makes a lighted tailcap a lot less attractive.

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

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I got them from lighthouse LED’s.

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It's a voltage divider -

Take the battery voltage 4.2V, and subtract the LED Vf 1.8V (or even 1.6V @1mA), this leaves 2.4V across the two series resistors, the 1k and the 560 (we'll ignore the driver for now).

2.4V / (1000 + 560) = 1.54mA, this is the current though the resistors and split between the two LED's (0.77mA each). Being in series, each resistor passes the same current. So the voltage drop across the 1k is 1.54mA x 1000 = 1.54V, and the drop across the 560 is 1.54mA x 560 = 0.86V. This is very close to enough to run the ATtiny. Either the MCU is not shutting down or this voltage keeps the OTC at 0.86V, which will interfere with memory.

You can increase the 1k, this will lower brightness, or decrease the 560 this will increase brightness. Or, for red LEDs, you may try them in series and use the 1k/560, this will increase brightness but stop working at a higher voltage, about 3.2V or so.

Because there are so many variables, driver resistance, Vf, battery voltage, etc. Calculations only get you so far, then you have to roll up your sleeves....

Edit: I started composing this before you came back with your results... I agree with Pilotdog about the LEDs being inefficient. Maybe try others?

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Kloepper Knife Works wrote:
I got them from lighthouse LED’s.


Weird, those are the exact led’s I have as well. I see you are using the Larger omten switches, so that would explain a little blocked light, but I’m still baffled as to why they seem so inefficient.

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

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I’ve got another red one to build, so I’ll be examining everything very closely to see if there is any difference in output and if so, why. I’m also going to sand the nylon washer thinner to try to minimize it’s effects. Honestly I’m hoping I just screwed something up (although I don’t THINK I did) because it’d be nice to be brighter AND more efficient. The LED that is, although I wouldn’t mind the same thing.

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Kloepper Knife Works wrote:
it’d be nice to be brighter AND more efficient. The LED that is, although I wouldn’t mind the same thing.

Good luck on that one Wink

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

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So results for #2 in red are identical to #1. With a 1k limiter and running off my power supply it’s dimmer than the steroid version running a 220 ohm with another 50 in series. I expect they’d be the same with the same limiting resistors.

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Well that’s less than ideal. I don’t know what’s going on.

My Favorite Modded Lights: X6R, S8 , X2R , M6, SP03

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

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