Path: utzoo!attcan!uunet!wyse!mips!prls!pyramid!decwrl!labrea!rutgers!gatech!bloom-beacon!mgm.mit.edu!wolfgang From: wolfgang@mgm.mit.edu (Wolfgang Rupprecht) Newsgroups: sci.electronics Subject: Re: MOVs Keywords: computer power protection line conditioning Message-ID: <6000@bloom-beacon.MIT.EDU> Date: 4 Jul 88 16:33:22 GMT References: <219@nfsun.UUCP> Sender: daemon@bloom-beacon.MIT.EDU Reply-To: wolfgang@mgm.mit.edu.UUCP (Wolfgang Rupprecht) Distribution: na Organization: Freelance Software Consultant, Boston, Ma. Lines: 36 >What exactly is the difference between buying a $150 line conditioning box >and soldering a couple of MOV capacitors [sic] across the outlet? about $140 Seriously you can buy lots of MOVs for the price of one of those nicely packaged anti-surge outlets. Remember, NEVER connect an MOV across a powerline without putting some sort of fuse protection upstream of the MOV. Not unless you really want to cash in on your fire insurance. ;-) (If you really want to see what an MOV does when it "blows" plug a 100V-peak one into a normal wall outlet sometime. Instant arc-light and mucho smoke and flames.) For a really deluxe surge suppressor box, get 1) fuse, for the "hot" [black] lead 1) inductive-capacitive line-filter (such as a Cornell-Dublier) for filtering noise 3) MOVs for major surges 3) gas-discharge voltage clamps to parallel across the MOVs for slightly faster response times. (and... lots of colored LEDs or neon bulbs for that special high-tech look!) PS. MOVs aren't capacitors at all. They are much more like a statistical network of zener diodes. The thicker the MOV is, the longer the mean-path through it is, and the higher it's effective zener voltage is. MOVs are such robust voltage clamps because they fail "gracefully". The failure of any small number of its 10's of thousands of constituent zeners hardly matters at all. --- Wolfgang Rupprecht ARPA: wolfgang@mgm.mit.edu (IP 18.82.0.114) TEL: (617) 267-4365 UUCP: mit-eddie!mgm.mit.edu!wolfgang