Re: ElectroMagnetic Compatibility and Tesla coils (fwd)

---------- Forwarded message ----------
Date: Sat, 25 Apr 1998 14:37:31 GMT
From: Mike Harrison <wwl-at-netcomuk.co.uk>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: ElectroMagnetic Compatibility and Tesla coils (fwd)

On Fri, 24 Apr 1998 21:18:57 -0600 (MDT), you wrote:

>---------- Forwarded message ----------
>Date: Fri, 24 Apr 1998 19:21:21 EDT
>From: SBJohnston <SBJohnston-at-aol-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re:  ElectroMagnetic Compatibility and Tesla coils
>JIM LUX wrote:
>>Here is my concern: Virtually all modern electronic equipment
>>(particularly PC's) has to meet fairly stringent EMC 
>>requirements, both to keep interference inside, but also to 
>>insure that it's behavior isn't corrupted by outside signals
>>(e.g. a TC output). At the simplest level this is accomplished
>> by putting it in a metal box, although in practice, this
>>doesn't even get close to meeting the fairly stringent CE and 
>>FCC requirements.
>>I can see an electronic device being affected, operationally, 
>>by the RF from TC, but as for actual damage, I find it more 
>>unlikely. Modern Electrostatic Discharge (ESD) precautions on 
>>equipment make it pretty immune to fairly high voltage 
>>(although low energy) zaps.
Remember there's a big difference depending on whether the 'target'
equipment is switched on or off - if off, you need to zap it with
enough energy to cause physical damage to the semiconductors.
However, if it's switched on, you only need enough energy to latch up
the CMOS structures within the ICs, and the unit's power supply will
do the rest,  if it can supply enough power. The very high di/dt of a
spark discharge is very effective at causing latch-up, and even a
relatively small discharge could be enough. 
Moral - always switch everything you can off before firing the TC, and
if anything you've left on starts misbehaving, switch it off
immediately - you may be lucky & prevent thermal damage from latch-up.
     ____                                                           ____
   _/ L_/  Mike Harrison / White Wing Logic / wwl-at-netcomuk.co.uk  _/ L_/
 _/ W_/  Hardware & Software design / PCB Design / Consultancy  _/ W_/
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