Hi there, A switcher has much more stresses on the components, since it usually switches the primary side rectified 110/220V high-voltage across a transformer. Thus the switching FET has to be very high voltage capable (about ~170V DC in the US), and the second component under stress is the primary high voltage capacitor, because it sees a very fast AC switching current on it (current draw is on when the FET is on, and off when the Fet is off). Also there has to be a fast snubber network to prevent the back-emf from destroying the primary Fet with over-voltage. A linear supply has none of these fast current/voltage transients on it, only a couple of diodes switching the 60Hz secondary onto a capacitor at low voltage. A secondary concern is thermally induced stress, switchers will usually be packed into a very small enclosure with very high power capability/density. This is not possible for linear supplies, since the transformer size will usually determine overall sizing. Compare a Laptop power supply size (usually these have between 40W and 90W rating!) to a similar rated linear supply. bye, Said In a message dated 6/1/2009 09:48:29 Pacific Daylight Time, hmur...@megapathdsl.net writes:
Is there something I don't understand in this area? What makes a linear supply more reliable than a switcher? My first guess would be a switcher would be more reliable because it would run cooler. That's probably assuming the same amount of design effort which is probably not a valid assumption if I'm comparing a brand-X linear with a brand-Z switcher. A quick glance at the general construction might give a better answer. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.