Quoting gardenyu : > > I went to Wikipedia and it tells that for a switching mode power > supply, it is a AC-DC-AC-DC process, and since the latter > conversions are at high frequency, thus they need a much smaller > transformer. This makes sense to me, although I still don't know > which one might have a higher efficiency. They must have their own > reason of living in the world. > > Would you recommend any stable and trustable power supply brand? I > need about 12-15V DC adjustable and 15-20A at output. Where are you? GW isn't too bad (Taiwan company). A lot of the supplies, including US makes, are re-branded mainland Chinese supplies and are a bit rough around the edges. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" s...@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist