Re: oops ("Kickback" and untuned coils)

To: tesla-at-pupman-dot-com
Subject: Re: oops ("Kickback" and untuned coils)
From: "Jeff Metschuleit" <jeff-at-lumitron-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Tue, 28 Mar 2000 08:06:02 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme
Is it possible that there is additional high frequency components in the
line conducted transients when the coil is out of tune?
Jeff Metschuleit

-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Monday, March 27, 2000 4:26 PM
Subject: RE: oops ("Kickback" and untuned coils)


>Original Poster: "Lau, Gary" <Gary.Lau-at-compaq-dot-com>
>
>>> Original Poster: "Lau, Gary" <Gary.Lau-at-compaq-dot-com>
>>>
>>> Hi Ed:
>>>
>>> I'd like to come to a better understanding of the hazards of coiling to
>>> appliances, and in particular, just what are these ill-defined demons.
>>>
>>> I don't understand your suggestion that an untuned coil is more prone to
>>> sending HV transients over the AC line.  My current thinking has it
where
>an
>>> untuned coil is simply not efficient at transferring the primary energy
>to
>>> the secondary, so the energy languishes in the primary tank circuit for
a
>>> longer than desired time, burning up energy in the gap and putting more
>>> cycles and wear and tear on the tank capacitor.  But I don't see any
>>> mechanism for this energy to get back to the AC mains any more-so than
in
>a
>>> tuned coil.  While the duration of each "bang" ringdown is longer, the
>>> magnitude of any coupled transients would be no greater.
>>>
>>> Regards, Gary Lau
>>> Waltham, MA USA
>>>
>
>>Original Poster: "Edward Wingate" <ewing7-at-rochester.rr-dot-com>
>
>>Gary,
>
>>An untuned coil will produce transient voltage spikes/peaks in the primary
>tank
>>that are much higher in amplitude than a properly tuned coil and the
>>untransfered energy does not just "languish" in the tank circuit, it finds
>it's
>>way back to the "mains" through the gap and transformer. Granted, a
>properly
>>tuned coil will produce a certain amount of kickback too, hence the need
>>for EMI
>>filters on the line feed, but not to the extent that an untuned or badly
>tuned
>>coil does.
>>
>>Harry Goldman, editor of the TCBA Newsletter once printed a letter from a
>>newbie
>>who wanted to know why there were SPARKS ARCING across the slots in the
>WALL
>>OUTLETS in his home when he fired his newly constructed Tesla coil! How
>long do
>>you think a microwave or any other solid state device with microprocessor
>>controlled displays or functions would last if plugged into those
outlets?!
>If
>>there were sparks across the outlets, what could be happening inside the
>>walls!!
>>
>>Ed Wingate RATCB
>>Brockport, NY USA
>
>I didn't mean to suggest that voltage spikes don't occur or that they are
>unlikely to damage appliances with semiconductor circuitry.  The maximum
>amplitude of the voltage in the primary tank circuit cannot exceed the
>(static) gap breakdown voltage, regardless of tuning.  This ignores the
>zero-gap-current-crossing transients, but these are also unaffected by
>tuning.  I simply don't see the mechanism to support the suggestion that
the
>mains spikes are larger or more troublesome when a coil is out of tune.  If
>anyone can explain this mechanism, that would go a long way towards finding
>a cure.  If not, I remain unconvinced that tuning is a factor.
>
>Gary Lau
>Waltham, MA USA
>
>