-=> Quoting Day Brown to Eugen Woiwod <=-
 DB> BTW: the typical surge sucker, either PC or modem types, uses a MOV to
 DB> shunt dangerous spikes to ground.  The Metal Oxide Varistor chosen for
 DB> this type of job us usually @130 VRMS AC. On the telco line, the RING 
 DB> signal is @90 vac, so the phone line type aint all that differnt.  The
 DB> MOV has a sort of "half-life" characteristic in that every couple of  
 DB> years, the voltage at which it will shunt goes up by maybe 50%. 
 Actually the clamp voltage goes down according to some technical
 references, and when it goes so low (170V or lower), it will be triggered
 at every AC power peak... and cause the MOV to heat up and creates a so
 called "Thermo-Runaway"... basically the MOV starts to smkoe and glow,
 eventually starts a fire...
 DB> So, if you don't remember when you bought your surge sucker, throw it 
 DB> out and get a new one... unless it's a "ZERO-SURGE", which don't use 
 DB> MOVs but uses inductive clamping.  If yours weighs a few pounds, then 
 DB> it likely has some kind of heavy transformer, and the hysteresis, or 
 DB> magnetic field lag, performs the spike suppression. 
 The shunt mode Surge supressor are everywhere... there is a company use
 "Series Mode" supression technique... they told me that while those
 companies use 9 cent MOVs they use 9 bux inductors... which are unlikely
 (they said "impossible") to degrade... if anyone's interested, check
 out "www.brickwall.com"... and no, they are not paying me to say this,
 but convience them if you can, to send me some paycheck for doing this :)
 BTW, exploding MOV are kinda fun... I did blow one up once... the MOV and
 the fuse are both blown to bits... great neat looking blue sparks... :)
... TIP - Empty Tic-Tac packs are great for small parts!
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