My recco for a 5W part is based partly because over-rating the part can't hurt reliability, partly because I find mounting a 5W metal-bodied resistor easier than a mingy little 1-1/2 - 2W one, and partly because there's little price penalty in getting the larger part. Diodes will work admirably well but are less-convenient to mount IMO. I like my devices fastened down. The tempting mounting hole in a TO-220 is electrically connected to the diode's innards, whereas a metal-body resistor's mounting holes are insulated from the electrical bits inside. But hey -- it comes down to a matter of style; either approach will work well as long as the guy doing the installation knows what he's doing. -- Mike "Rocket J Squirrel" Elliott 84 Westfalia: Mellow Yellow ("The Electrical Banana") 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano Bend, OR KG6RCR
On 3/18/2009 3:23 PM David Beierl wrote: > At 06:06 PM 3/18/2009, Rocket J Squirrel wrote: >> Get one rated to handle the power, preferably a nice 5W >> aluminum-bodied one that can be easily bolted to something. > > Given P=I^2 R, dissipation at 0.67 amps would be .9 watts -- so a 1 > 1/2 or two watt device should be plenty. > > I still favor diode drops for this sort of thing, mostly personal > prejudice I guess. > > -- > David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/ > '89 Po' White Star "Scamp" > > |
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