Re: Moddoo Customs: Triple CREE XP-E (reservations open)
That is a really nice-looking product. Some questions/comments:
It looks like the copper LED mounting plate might be thicker than the Cutter star that was used in version 1. Is that the case or is the copper plate the same thickness? If it's a different thickness, that might cause some issues if one wanted to upgrade the LEDs (e.g., to a triple XP-G) using a standard star (e.g., the optic might be recessed below the top face of the heat sink). Also, the location of the screw holes look to be different vs the screw cutouts for the Cutter star, which would preclude using the screw holes to secure a Cutter star.
I don't see any wires to hook up the LEDs in parallel. Does that mean that you've also designed the copper mounting plate to connect the XP-E's + and - solder pads in parallel automatically when you solder the LEDs to the plate? I assume that's the function of the groove in the plate -- electrical separation of the + and - pads on the emitter bases? I also assume that it set up so that LED- is the same as GND, which would be accomplished via screws connecting the copper plate to the aluminum heat sink. So you then just run a wire directly from the driver LED+ to the center section of the copper plate? The AMC7135 and the SOB drivers both share LED- and GND, so this works out. But not all drivers share LED- and GND (although off-hand I can't think of one that is 14mm or 17mm -- the much bigger 1.1" hipCC is an example). If the copper plate is the same thickness as the Cutter star, then IMO this copper mounting plate is a really nice improvement overall. Eliminates using hookup wires to connect the LEDs in parallel, looks cleaner, and has better thermal mass than an aluminum MCPCB.
For my Cutter star, I had to file the star for it to fit into the top of the heat sink. A little thermal compound, and the star has tight, full thermal contact at the bottom and sides. So, the claimed advantage of increased thermal contact using the copper plate isn't clear to me. You will get greater thermal mass with the copper, which is a good thing. However, I probably would have used a 100% brass heat sink to get comparable thermal mass to copper, and better than that for aluminum. A brass heat sink would also allow directly soldering ground connections between the driver and sink without needing the custom driver contact collar.
The black anodizing is nice, but do you really think you get much thermal transfer via radiation vs conduction to take advantage of increased emissivity?
