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LED replacements and upgrades

I couldn't help but notice the recent news of the CREE XLamp MK-R and the much higher lumens it supports in a slightly larger form factor (7mm x 7mm). I have to wonder what possibilities there are for future upgrades of the LED in the HexBright as LED technology advances or replacements are needed.

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Well, currently we could increase the lumen output fairly significantly.

The 2 key limitations are run time (we are battery powered) and heat.

I suspect that the larger form factor is to provide greater heat transfer away from the LED, but given the same body, we have the exact same thermal issues.

What I'm most interested in is improvements in efficiency per lumen, not max output.

I suspect Christian will be keeping an eye on this, though.

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+1 on the greater efficiency over greater output. I was thinking of using the hex for a front bike light, but it is actually too bright as it is in the flashing mode. The street signs light up so bright I have trouble seeing everything else.

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Jamie: Well, you have a programmable flashlight - I would use a variable brightness mode that saves to EEPROM when certain events happen - a long press or a tap, for 2 examples, so that you can save 2 brightness levels and read them back later. While it's good to have a flashing light on a bike, a strobe - where it's dark between the flashes - could be less helpful than a medium light that flashes up to a brighter level when strobing - that way you still get the noticeable strobing effect for oncoming cars, but you don't spend half your ride in darkness. And you get to set the brightness levels.

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The MK-R has a Vf of around 12V. The XR-E used in the Flex is around 3.3. The LED driver in the Flex maxes out at 5.5V and is set by hardware to less than that. The MK-R is also 2 mm larger.

So, using it in the Flex would require a new circuit board, and probably a new lens.

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@Jamie - remember you can change the brightness of your flashing mode. I'm not very experienced in coding, but I believe in the Factory Sketch, the section to look at is:

case MODE_BLINKING:

case MODE_BLINKING_PREVIEW:

Serial.println("Mode = blinking");

pinMode(DPIN_PWR, OUTPUT);

digitalWrite(DPIN_PWR, HIGH);

digitalWrite(DPIN_DRV_MODE, HIGH);

break;

After line: digitalWrite(DPIN_DRV_MODE,HIGH);

Add line: analogWrite(DPIN_DRV_EN,255);

Where 255 can be any value between 0 and 255. Zero being lowest and 255 being brightest.

I trust someone will correct me if I'm wrong about this, or provide a better way to get the results Jamie is looking for.

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Jens -

That won't do anything. Note that there's a section to handle the blinking mode, which contains this:

// Do whatever this mode does

switch (mode)

{

case MODE_BLINKING:

case MODE_BLINKING_PREVIEW:

digitalWrite(DPIN_DRV_EN, (time%300)<75);

break;

}

the digitalWrite... line just sets DPIN_DRV_EN low or high depending on the time (it will be on the first 75 of every 300 ms) - that's what makes it blink. Setting it high with digitalWrite results in exactly the same thing as doing an analogWrite 255.

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The easiest way I can think of would be (using the hexbright library):

if(hb.light_change_remaining()==0) {

hb.set_light(MAX_LEVEL, MAX_LOW_LEVEL+1, 333);

}

This would reduce the light from the max brightness (1000), to just above where we switch to low brightness (501), over 1/3rd of a second, and restart the cycle once the light stops changing.

I'm guessing this would be slow enough and long enough to provide decent vision, while still giving you your attention-getting strobe.

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I made a video comparing the original Flex LED with the CREE XM-L2 Replacement LED Board

https://www.youtube.com/edit?video_id=xU...

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TC M will be eternally grateful.
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