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Wire length,resonance, and Q (fwd)
----------
From: Mark S Graalman [SMTP:wb8jkr-at-juno-dot-com]
Sent: Saturday, May 30, 1998 8:00 AM
To: tesla-at-pupman-dot-com
Subject: Re: Wire length,resonance, and Q (fwd)
Terry and Greg,
Perhaps if you check out my article in the TCBA
news it will be of interest:
An Analysis of a Tesla Coil
TCBA news Vol 12 #4 pages 14-16 1993
Actually I think we're quite in agreement here,
but for a tesla secondary to be viewed as a
lumped inductor Cterm has to be VERY large in
comparison to Cself. But even under that
condition it is still a resonant transformer
(narrowband response)
Mark Graalman
On Fri, 29 May 1998 23:22:42 -0500 Tesla List <tesla-at-pupman-dot-com> writes:
>
>----------
>From: terryf-at-verinet-dot-com [SMTP:terryf-at-verinet-dot-com]
>Sent: Friday, May 29, 1998 3:08 PM
>To: Tesla List
>Subject: Re: Wire length,resonance, and Q (fwd)
>
>Hi Greg,
>
>At 11:36 PM 5/28/98 -0500, you wrote:
>>
>>----------
>>From: Greg Leyh [SMTP:lod-at-pacbell-dot-net]
>>Sent: Thursday, May 28, 1998 7:17 AM
>>To: Tesla List
>>Subject: Re: Wire length,resonance, and Q (fwd)
>>
>>Mark S Graalman wrote:
>>
>>> I have to wonder here if there isn't a simple
>>> misunderstanding of 1/4 wave resonance, the fact
>>> that we are talking about an ELECTRICAL 1/4 wave
>>> and not a PHYSICAL 1/4 wave. That a 'monopole'
>>> tesla secondary is a ELECTRICAL 1/4 wave from
>>> the bottom to the top, and any situation where one
>>> has a current node at one end and a voltage node
>>> at the other is being operated as a 1/4 wave electrically
>>> regardless of its physical length.
>>[snip]
>>
>>This is true, and devices such as waveguide stubs and antennas
>>often operate in this 1/4 wave mode. However, a TC secondary
>>_does not_ behave in this way, for the following simple reason:
>>
>>There is no actual voltage node (max V, min I) at the top.
>>
>>Although there is a current node at the base (max I, min V),
>>the top winding carries both the maximum voltage _and_ nearly
>>the maximum current, just like in a standard HV transformer.
>
>
>My tests show that the all the current isn't making it to the top
>electrode.
>I think the self-capacitance is storing energy and thus "stealing"
>some of
>the current before it gets that high.
>
>
>>This current at the top simply goes into charging the top
>>electrode, which has a lumped capacitance back to ground.
>
>
>I agree 100%!!!
>
>
>>The current going into the arc is typically only 30 to 40%
>>of the total current being delivered to the top electrode.
>>If you change the "electrical length" of the TC secondary,
>>this will still be the case.
>>
>>
>>-GL
>>www.lod-dot-org
>>
>>
>
>
> My recent paper describes a current test I did on my research
>coil.
>I found that the current going into the top electrode was about 60% of
>the
>current at the base (no breakout). I found that this almost exactly
>matched
>the ratio of top to self-capacitance in my system. Do you (or any one
>else)
>have any similar results that might add to this?
> My results also show that the secondary was a lumped inductor
>with
>no standing wave effects. Theory (the new one) suggests that the
>phase was
>off by 0.1 degree but that is due to the propagation speed of light).
>Far
>below my ability to measure.
>
>My early tests with arcs are still too early to comment much on. I am
>building up new devices to measure this accurately. However, the arcs
>seem
>to be oscillatory high current pulses that drain the top terminal.
>The
>Cself may be harder to drain do to it's distribution on the secondary
>(the
>inductance may get in the way).
>
>Much to learn here.........
>
>
> Terry Fritz
>
>www.peakpeak-dot-com/~terryf/tesla/experiments/experiments.html
>
>
>