I updated my MELD multicolor driver to hardware version 3, and finished three lights in quick succession:
v3 hardware brings a lot of performance improvements to the SEPIC converter (white channel) with bigger inductors and a different package for the controller which improves thermal performance. There’s also an electrical change that allows the SEPIC to run better from primary cells that are almost depleted. The new layout allows the boards to stack more efficiently as well:
The HL50 didn’t have enough height to fit the boards normally, so I free wired the inductors so they could sit in the cavity behind the LED board:
I fed wires through and got the driver in place:
and then wired in the LED board (which had to have one side shaved down):
The reflector had to be drilled slightly to fit all the LEDs in. All in all, a pretty quick job, and now it is the ultimate headlamp!
The C10R was fairly easy to adapt the driver to; I just epoxied a momentary switch onto the board so that it would contact the rubber boot:
I got the driver wired up and prepared a MELD XP LED board that fits an XP-L for lights with bigger reflector openings:
With some notches in the LED board to match the holes in the body, it drops in with thermal grease and gets wired up:
The EX11 was a bit more of a challenge. There is so little room inside the pill of a piston drive light, so I had to design a custom board. I tried for a long time to fit standard MELD hardware into it, but couldn’t, so I switched to linear regulation and restricted use to rechargeable cells. Each color gets one AMC7135 and the white channel has three.
With some careful layout work I was able to get them to stack just barely short enough to fit in the pill:
And then the madness began. The reflector opening wasn’t big enough to fit my standard LED board, and I didn’t want to drill it. I eventually decided to go back to a crazy method I’ve used before of setting the color LEDs into the reflector. To do this I drilled holes evenly spaced, then filed the metal down to thin the walls (to raise the LEDs up). After that, I free wired all the LEDs:
And then one by one set them into their holes, applied arctic silver epoxy, and held it in place until the epoxy set (four separate times!):
Here’s the result:
Along with the update to v3 hardware, I wrote a firmware update that includes a color lock feature: the user can choose any mix from the continuous spectrum of colors, then replace white functions with that color. This gives you a way to use a chosen color with brightness ramping, max/min shortcuts, and variable speed strobe. I’ll do a video soon to demo that.
thanks for reading!