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Re: Shielding Computers



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William Noble writes....

> I am not a tesla expert (clearly) and so will defer to those who are, but 
> there are some techniques for shielding against EMP (the pulse that goes with 
> a nuclear explosion) which would seem to me to cover it pretty well.  Of 
> course you may not want to bother.
> 
> 1. enclosures must have good electrical seal all the way around - that would 
> mean putting a metal cover over the fronts where the disks go in, and a very 
> fine screen over the fan.
> 
> 2. EMP diodes across all low level signals - for example, keyboard, telephone, 
> speaker, etc - back to back zeners may also be ok, but zeners are slower as I 
> recall
> 
> 3. usual filtering on power supply, and then internally, add EMP or other over 
> voltage protection circuits between the PS and the other electronics.  (I just 
> happen to have 2 such things left over from some computers I upgraded - 
> overvoltage SCR devices to crowbar the 5V, etc that mate to the power plug 
> into the motherboard - e mail me separately if you want them
> 
> 4. I personally would want to use an isolation xformer or something if the 
> computers were to be powered up. if off, then I don't see why unplugging them 
> and wrapping them in aluminum foil wouldn't do the trick.

My advice - don't risk it. I spent two days repairing half a workshop 
full of gear after blithely testing a rather modest Marx generator 
that emitted huge EMPs. OK, it wasn't a TC but... I have experienced 
damaged to parallel interfaces that had cables plugged in when 
running a TC some distance away. An isolating transformer is 
absolutely *no protection whatever*. Unplug everything that can be 
unplugged, then unplug everything else. A kickback once destroyed 
what was left of some old rubber insulation in a drill press. The 
bang woke us up.

Malcolm






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