How did you get the lens for this setup? I’ve found the actual diodes and I think it would be cool to make something like this, but I don’t know where to find the lenses at.
Any words?
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I don’t 100% remember where I got the optics from, but I think it was from Carclo. Ledil also makes some, as well as others. http://www.carclo-optics.com/optics-for-leds/tir/diameter-20.0mm/
The problem I had was that even with an elliptical beam pattern, there’s not a sharp enough cutoff for road use. Too much spill making it into the eyes of oncoming drivers to be a great idea.
For my ebike, I decided to use a commercial projector low-beam with a LED bulb to provide a nice clean horizon line.
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Re: LED choice, that’s a decision you’ve got to make based on experience and your needs. You can look up datasheets on each different emitter to see if any have a particularly good or bad set of characteristics for your application.
In general, the smaller the die (light emitting surface) of the LED, it will result in a tighter beam for a given optic.
The larger the die, generally the more efficient it will be at a given power level.
3-up assemblies split the power between three LEDs instead of one, which also improves the efficiency, but the optics won’t be as sharply focused.
I’ve always been a Cree fanboy, due to their excellent efficiency and very high power density, but Luxeon LEDs are available in a much wider range of colors.
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I’ve been digging in that a bit
I have some elliptical lens on the mail, but looking at if we could make a custom lens with a sharp cut off following cars light regulations
since the LEDs that they use in the 5W and 10W kits are the same, the watt distinction is about how much heat the casing is rated to dissipate?
I think I would get the 10W kit with the spot optic, just want to see father down the road.
Shame the included driver is limited to 32V
https://www.ledsupply.com/led-drivers/buckpuck-dc-led-drivers
Both that, and also what specific drivers are being used. You can take an LED capable of handling 100W and drive it at 5, or 10, and it’ll be perfectly happy. In fact, underdriving LEDs improves their efficiency and makes them last longer.
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Yeah, it’s all about compromises. The buckpucks are very compact and provide good controllability and efficiency.
For my board (10S), I used an XP power LDU56 like this one. 60V input, and can drive strings of LEDs up to a couple volts less than Vin. Since the maximum output current is only 1A, to get more than ~3w out of it I used a multi-die LED with a 12v forward voltage.
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Really interesting. Do you think there’s a way to make these cree diodes work for a close-to-ground application like a hummie deck headlight? I would be interesting in utilizing one of these and designing a case and what not for it.
Does anyone know what LEDs the Lacroix headlights use? @Pedrodemio design is really cool but I can’t get my hands on Lacroix headlights so I’d want to recreate it from the base level
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Would be interested to see what you had in mind for this.
with this kit I was going for the barrel flashlight over the truck idea like this
It would be cool to see two LED arrangements attached cleanly to the front/underside or possibly slightly built into the deck.
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Hm well I’m still in brainstorming / idea phase, I was thinking one or two nicely integrated or slim form factor. I just can’t get behind the huge deck mounted flashlights
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That’s what I used for mine. It was very, very bright and worked pretty well except for the light bleeding up into the eyes of oncoming traffic. I dunno if I’d trust it enough to ride at a significant speed at night, but it was far more than a “be seen” light.
It’s really difficult to get good road lighting out to a decent distance with the source only like 4" off the road.
Maybe with a custom optic that has a very very narrow (in one axis) elliptical beam with a sharp cutoff would make it more practical.
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Hmm good to know. I think I’ll just order a few of these diodes and keep coming up with ideas for them until then. I’m mostly? going for being seen, but I have a bunch of small headlights I can use for that, so this is more of a being able to see the road decently sort of a thing
Would you have an optic on this page that you’d recommend? I have no idea what I’m looking at, I hated the lenses part of PHY203 lol
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I used this elliptical one. http://www.carclo-optics.com/optic-10003l25?optictype=tir&diameter=20.0
The output shape is dependent on the shape of the LED die itself, so picking something like an XPL HI (HI = high intensity, has no dome/lens for a smaller apparent emissive area) will result in a sharper, tighter pattern, whereas something like an XHP50 will be a lot more floody and less-controlled.
They give waveforms for lots of example LEDs, which helps.
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Okay interesting. Do you know how to determine the distance from the diode the lens is supposed ot be placed? It kind of looks like it might fit into the lens, is that true?
There’s a holder that the lens fits in, that sits on the star to give the desired spacing. There are three different part numbers and I don’t know what the difference is between them. 10732, 10734, and 10736.
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Just did some more digging and it turns out there are a whole range of different numbers, and the numbers determine different reflector spacing. I don’t know if there’s a way to determine the optimal one needed without testing.
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I think I’m gonna order 3 of the XHP35 12V cree modules with the 20mm copper PCB in cold white. Hopefully they don’t take more than a month to arrive, I also have no clue how expensive the optics are yet lmao
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They’re a buck or two a piece, not terrible.
Okay, so after you select the specific LED you’re using, the carclo website will tell you exactly which holder to use that will hold the optic at the optimal position. Looks like for an XHP35, the holder you want is a 10733.
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My go-to source for all things LED and flashlight related (I build flashlights from scratch sometimes) is kaidomain.com. They’ve got lots of LEDs, drivers, copper and aluminum PCBs in various sizes, and I’ve had good luck with them. Here’s their page on Cree XHP-series LEDs. http://kaidomain.com/Flashlight-DIY-and-Tools/LED-Emitters-or-LED-Star-on-PCB/cree-xhp-series-leds
mtnelectronics.com is another great resource. They’re based in the US, so their shipping is much faster but their prices are also predictably higher.
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Very cool. These look a lot like the lacroix lights actually
http://kaidomain.com/KD-2-x-Cree-XM-L2-U2-4-10-Mode-2200-Lumens-Bike-Light
So basically per light set up, I would need 1x lens, 1x holder, and 1x diode. Then after that, I need to figure out what the heatsink would look like and then design the rest of the holder.
You seem to be pretty knowledgable on the lights side, is a real LED driver actually necessary or can I just connect two bulbs for example straight to a CC buck converter?
I ran my 4x cheap foglight headlights on a buck converter on my last board. They weren’t very bright but they did the job of being seen
Ordering:
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