D.I.Y. Illuminated tailcap

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Kloepper Knife Works
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I’m baffled, but now that I think about it the double blue tailcap is pretty dim too (although it’s running a 4.7 or 6.8k limiting resistor). I may bump that to a 220, build a single in blue and a single in red at 2.2k and compare them all.

I can’t fathom why the single might be brighter, but the single I built in green with a 2.2k is BRIGHT.

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Kloepper Knife Works wrote:
I’m baffled, but now that I think about it the double blue tailcap is pretty dim too (although it’s running a 4.7 or 6.8k limiting resistor). I may bump that to a 220, build a single in blue and a single in red at 2.2k and compare them all.

I can’t fathom why the single might be brighter, but the single I built in green with a 2.2k is BRIGHT.


I’ll be interested to hear what you find.

So far I have done 2 red doubles, 1 red single, 1 green single, and 1 blue double all with the 0805 led’s from lighthouse. On all of them, I have had 560ohm on the driver and 2.2k-6.8k on the tail.

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Kloepper Knife Works
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Not something I’d normally consider, but do they carry a low output version of this LED and I just got the wrong one shipped to me?

With the fact that I’m getting a measurement of 5.7mA it’s hard to imagine that they’re having a problem with getting enough power.
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Kloepper Knife Works wrote:
Not something I’d normally consider, but do they carry a low output version of this LED and I just got the wrong one shipped to me? With the fact that I’m getting a measurement of 5.7mA it’s hard to imagine that they’re having a problem with getting enough power.
No i don’t think they do. I’m more inclined to think we have something stealing current somewhere. Where are you measuring the draw?

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Kloepper Knife Works
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I’m putting my DMM in line with the negative battery terminal to brass button and a jumper between the body and tailcap ground.

Kloepper Knife Works
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Keep in mind that driving it from my power supply doesn’t increase brightness, so I don’t think it’s driver related.

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Kloepper Knife Works wrote:
I’m putting my DMM in line with the negative battery terminal to brass button and a jumper between the body and tailcap ground.

I’m staring at your pictures and don’t see anything wrong. I have gotten a board from osh with an internal short one time, but only one out of the batch was like that.

Any way to measure the draw at one of the led’s to confirm how much they’re getting? Is it possible they could have gotten overheated during assembly? (unlikely since we’re talking about 4 different emtters)

Just spit-balling here.

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Kloepper Knife Works
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pilotdog68 wrote:
Kloepper Knife Works wrote:
I’m putting my DMM in line with the negative battery terminal to brass button and a jumper between the body and tailcap ground.

I’m staring at your pictures and don’t see anything wrong. I have gotten a board from osh with an internal short one time, but only one out of the batch was like that.

Any way to measure the draw at one of the led’s to confirm how much they’re getting? Is it possible they could have gotten overheated during assembly? (unlikely since we’re talking about 4 different emtters)

Just spit-balling here.

That’s a tall order, but I’m committed to the cause and I have some pretty pointy leads so I think I can make that happen. I’m about to get the boy from school though, so further progress will be on hold till later tonight.

Kloepper Knife Works
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So, when powered from the spring side, dim. Power applied to switch side, bright. I think it’s the damn boards.

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Kloepper Knife Works wrote:
So, when powered from the spring side, dim. Power applied to switch side, bright. I think it’s the damn boards.

Well at least that would explain a lot. Just looking at the boards, are the via’s all present and accounted for?

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Kloepper Knife Works
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I think so. Should I try filling them with solder?

pilotdog68
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I’d check for continuity/shorts first. Its drawing a lot from the battery, so that power has to be going somewhere

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Kloepper Knife Works
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Running off of a power supply after filling the vias:

Powered completely by spring side, dim
Negative on spring, positive directly to LED, dim
Positive to outer ring of spring side, negative to LED, BRIGHT!

So a problem between spring pad and back side then.

Kloepper Knife Works
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Nope, even when powering the negative switch contact it’s dim. I’m going to try to jumper from there to the negative pad on the resistor.

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Well the negative goes through the resistor, so if you’re connecting power directly to the led- pad, you’re bypassing the resistor.

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

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Maybe there’s a problem with the trace leading from the r1 to d1

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Kloepper Knife Works
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I’m starting to question the theory. I think I was just bypassing the resistor on the board hooking it up that way. I tried one directly on the power supply @ 1mA compared to 2 directly across the LED’s and they were similar, through the resistor the ones on the board got a lot dimmer. I need a break for an hour, it’s driving me crazy.

Bob Loblaw
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I built 2 of these using a single 3mm rgb led i pulled from an rc helicopter. One for a DD and one for a 105c, neither one needed the resistor on the driver or had any change in the memory function. I tried the resistor on the BLF DD and that caused the mode memory to fail. I am just using the standard switch pcb with a resistor in series with the led. So its wired like this: spring pad – resistor – led – outer ring. the spring side is the – connection for the led.

Kloepper Knife Works
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So after some sleep I’m back to troubleshooting. I’ve got another board with all the vias filled with solder, and tested the resistance of every part of the circuit path and everything is fine with the board as far as I can tell. I’m going to put 2 greens on it at 1k and compare to the 2 red 1k brightness. Pictures soon.

Kloepper Knife Works
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I think all this troubleshooting can finally be done. The red LED’s simply aren’t as bright as the green (and possibly others). The green LED’s are pulling 1.8mA in this picture using a 1k resistor. The reds are pulling 2.4mA using a 1k(difference due to forward voltage I believe). The green is obviously significantly brighter on less current.

Kloepper Knife Works
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Blue and green appear to have similar output at the same currents. I think the forward voltage of the LED’s is to blame for the difference. Red (Vf = 1.8-2.2v) requires 3-4x the current for equivalent brightness to the LED’s with a Vf of 3-3.2v, by calibrated eyeball lumen measuring device. (aka, perceived brightness)

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Kloepper Knife Works wrote:
I’m baffled, but now that I think about it the double blue tailcap is pretty dim too (although it’s running a 4.7 or 6.8k limiting resistor). I may bump that to a 220, build a single in blue and a single in red at 2.2k and compare them all.

I can’t fathom why the single might be brighter, but the single I built in green with a 2.2k is BRIGHT.

The blue sounds perfect! I’m sorry you aren’t pleased as this is exactly what I intend to do.

"Those who hammer their guns into plows will plow for those who do not."

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Kloepper Knife Works wrote:
Blue and green appear to have similar output at the same currents. I think the forward voltage of the LED’s is to blame for the difference. Red (Vf = 1.8-2.2v) requires 3-4x the current for equivalent brightness to the LED’s with a Vf of 3-3.2v, by calibrated eyeball lumen measuring device. (aka, perceived brightness)

I’m beginning to think we are getting different numbers because your customers want them brighter than I do. This a dual green (560/2.2k) I just built today in my S6 (took a lot to fit it in an S6 btw). After the picture, I changed the resistor because it was a little brighter than I wanted.

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

Icarus
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Interesting info! I'm still waiting for my boards and some parts as well. Thanks for posting! I'll go for blue and maybe I will green too.  

Kloepper Knife Works
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Really any color is fine for low output levels from what I’m seeing. It’s when you want it bright enough to see in a well lit room where the differences come into play in a big way.

Blue and green seem to be the most efficient, and honestly I’m not shocked I guess. In addition to the fact that I think the Vf is at play, I don’t see many high output red LED’s in flashlights either. I think the material that filters the light into red from the LED has a big effect on output. This is why high CRI LED’s are generally lower in output than their low CRI equivalents. Blue has the advantage of needing less filtering and we perceive it to be brighter than red for the same lux value. Green is the same way, less filtering than red and higher perceived brightness for the same lux.

Add all these little things together and you have a red LED that is hard to get big brightness from when you compare it to green or blue.

Halo...
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Kloepper Knife Works wrote:
Blue and green seem to be the most efficient, and honestly I’m not shocked I guess. In addition to the fact that I think the Vf is at play, I don’t see many high output red LED’s in flashlights either. I think the material that filters the light into red from the LED has a big effect on output. This is why high CRI LED’s are generally lower in output than their low CRI equivalents. Blue has the advantage of needing less filtering and we perceive it to be brighter than red for the same lux value. Green is the same way, less filtering than red and higher perceived brightness for the same lux.

Only white leds use a phosphor layer (and odd leds like pink). Colored leds produce their color directly, no phosphor layer or filtering.

Green is perceived as as brighter to our eyes.

Kloepper Knife Works
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Halo… wrote:
Kloepper Knife Works wrote:
Blue and green seem to be the most efficient, and honestly I’m not shocked I guess. In addition to the fact that I think the Vf is at play, I don’t see many high output red LED’s in flashlights either. I think the material that filters the light into red from the LED has a big effect on output. This is why high CRI LED’s are generally lower in output than their low CRI equivalents. Blue has the advantage of needing less filtering and we perceive it to be brighter than red for the same lux value. Green is the same way, less filtering than red and higher perceived brightness for the same lux.

Only white leds use a phosphor layer (and odd leds like pink). Colored leds produce their color directly, not phosphor layer or any filtering.

Green is perceived as as brighter to our eyes.
!http://www.yorku.ca/eye/photopik.gif!

That’s good to know. I guess half my theory wasn’t worth the words used to type it out. It does appear that blue has a slight perception advantage over red possibly, and obviously green has a huge one.

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Maybe I’m the only person still doing these, but I’ll share anyways.

I finally got around to making a smaller version (17mm) of the dual-led board. This will fit lights like the Convoy S series and many others.

Please note I just ordered this myself so it’s technically untested, although it’s essentially the same as the larger board. Also added to OP.

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

Major Projects:  Illuminated Tailcap, TripleDown/TripleStack Driver

devman
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pilotdog68 wrote:
Maybe I’m the only person still doing these, but I’ll share anyways.

Thanks! I haven’t done it yet, but it’s on my “to do, if I ever get a chance to stop and breathe” list.

scottyhazzard
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Thanks, Pilotdog.

"Those who hammer their guns into plows will plow for those who do not."

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