On Feb 22, 2006, at 11:45 PM, Peter Todd wrote: > I just started a project that will be a cube with 6 led matrix > displays, one on each side, using 5x7 led modules. Each side > will end up as a 35x35 matrix Hmm. That's equivalent to an LED-matrix sign 1 character high by 210 characters wide, which is... very large for that sort of thing. > One challenge I see is power. No Duh. 7350 LEDs. Ouch. > Peak power, for all leds on, is about 16amps per side! Or about > 100amps for the whole board! That's just nuts...Is there such a > thing as a simple, self-contained switching regulator that can > handle a decent amount of current? I'd like something as simple > as a 3-pin regulator, no external components or anything. > Sure. There are LOTS of these little DC-DC converters aimed at telco and comm equipment, that convert ~48V DC to your choice of output voltage at frankly incredible efficiencies in amazingly tiny packages. 200W per cubic inch or so. For instance, less than 2.5x1.5x0.5 inches, 5V at 40A: We sprinkle them like candy through the larger cisco routers, for instance. Don't ask how much they cost, though. And don't ask me where you get the 48V supplies to provide at the input, either... (On the other hand, these can frequently be found in discarded last-generation comm gear. I could probably come up with quite a few in a hour's worth of dumpster-diving (although the current crop probably output 1.8 to 3.3V...) Since this isn't the first time you've run into power problems, I think you should do some research on distributed power. Just because you need 5V at 100A doesn't mean you need a SINGLE 5V regulator that can deliver 100A; a half-dozen 12A supplies MIGHT be a lot easier... Of course, you won't be doing "all LEDs on", since you said "wireframe", and the peak current isn't appropriate since that's for a momentary pulse in a multiplexed display (max 6*35 LEDs on at a time at maybe 50mA; only about 10A required! Less than that since the wireframe won't light up full rows on all sides at once. Probably.) I hope you realize that this thing is likely to be to hot to handle. That 10A at 5V works out to about 50 watts, which will heat up something this size (less than 10inches on a side?) quite happily to an impressive temperature. And it's already been done (in 2d, anyway) with laptops and their internal 'drop sensors.' http://osxbook.com/book/bonus/chapter10/ams2hid/ BillW -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist