On 6/26/08, Olin Lathrop wrote: > Dario Greggio wrote: > > I planned to have (as I already did in my previous home) 12 or 24Vcc > > around the house to be used for remote device, small actuators and > > such. > > I would use the highest you can get away with and stay under the regulatory > limit where anyone cares. I think that is 48V around here, but I haven't > really looked. > > If allowed, 48VDC sounds like a good tradeoff. It is low enough to be safe > in most circumstances, but high enough that you significantly cut down the > size of the conductor for the same power delivered. Put a small buck > regulator on the front end of all devices. 60V transistors are still small, > cheap, and efficient, so this will be easy to do. Even a poor buck switcher > will be more efficient than linearly regulating 12V down to 5V. 48V is also > high enough that a diode drop isn't a large fraction, but low enough that > Schottky diodes are still realistic. 80% efficiency should be possible > without doing anything particularly fancy, like synchronous rectification. > Say if you have a single-stage buck converter, the efficiency from 24V->5V will be better than 48V->5V. 12V-->5V is even better. Xiaofan -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist