Path: utzoo!attcan!uunet!husc6!uwvax!rutgers!ucsd!nosc!helios.ee.lbl.gov!lll-tis!ames!oliveb!olivey!gnome From: gnome@olivey.olivetti.com (Gary) Newsgroups: comp.sys.mac Subject: Re: crash and burn!!! Why no fuse? Message-ID: <27429@oliveb.olivetti.com> Date: 17 Aug 88 02:26:13 GMT References: <561@calvin.EE.CORNELL.EDU> Sender: news@oliveb.olivetti.com Lines: 21 From article <561@calvin.EE.CORNELL.EDU>, by johns@calvin.EE.CORNELL.EDU (John Sahr): > Because the transistor/diode switch would probably blow up faster than any > fuse if it failed, it might be pointless to put even a $.50 fuse in the > SE or Mac II... > I am just guessing, based on what I've learned about these type of supplies. > John Sahr (johns@calvin) [opinions expressed are my own alone] Fuses are very good in preventing certain types of failures from becoming fire hazards, but in general, they won't really protect a hell of a lot in a computer system. The semiconductors will blow much faster than a fuse. Don't forget, if I remember correctly, a fast-blow fuse will blow in 1 minute at 200% overload, others are much tougher to blow-out. They're great for dead-shorts (impulse power >10x the rated amount). Even with this point of view, I still over-fuse anything I have design responsibility on. I also believe in power-supply crowbar circuits -- a lot. Gary