From: Bert Hickman
Date: Thu, 21 Jun 2001 06:20:35 -0500
Subject: [TSSP] [Fwd: Direct Voltage Measurement of Topload Voltage for TSSP]
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All,
It turns out that Greg Leyh did indeed use a stack of capacitors through
the center of his secondary, but this was done to add lumped C to the
topload and not to make any voltage measurements. Greg's response is
attached. Greg does provide some suggestions on how one might construct a
capacitive divider using a circular plate placed directly above the toroid
to eliminate any field effects from the secondary. And after reading
Terry's post this morning, I'm also convinced that a pure capacitive
divider will indeed be the most straightforward way to go...
-- Bert --
--
Bert Hickman
Stoneridge Engineering
Email: bert.hickman@aquila.net
Web Site: http://www.teslamania.com
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Date: Thu, 21 Jun 2001 00:17:20 -0700
From: lod@pacbell.net
Subject: Re: Direct Voltage Measurement of Topload Voltage for TSSP
To: Bert Hickman
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> We are at the stage in the Tesla Secondary Simulation Project (TSSP) that
> we need to be able to make some direct voltage measurements on the
> secondary of a Tesla Coil with minimal (or predictable) disruption of
> the output.
>
> I seem to remember a post on the TCML quite a while back where you had used
> a chain of vacuum caps (or ceramic doorknob caps?) to form a capacitive
> divider down the center of one of your systems. If this was the case, could
> you provide a bit more specific information about how you constructed
> and calibrated it? Also, how well did it work, and are there any design
> tips you could provide?
Hi Bert,
The capacitor stack that I placed in my coil was not for
measurement purposes, but rather to see if increasing the
top capacitance improves the arc performance. I didn't attempt
to figure out an exact calibration for the division ratio,
as there would be too many unknowns regarding the effects of
the internal E-field on the capacitor stack.
For measuring the output voltage, I'd probably suggest that
an external capacitive divider is the best bet... such as a
metallic disk about the same size as the toroid, suspended
directly above the coil and spaced at least 5 toroid diameters
away. This way the disk only sees the toroid e-field, since
the coil's field is shadowed by the toroid.
Divider calibration would be obtained by suspending the toroid
at its normal height, but without the coil under it. A known
HVAC voltage is applied to the toroid and measured. The resultant
signal from the disk should go through a single pole integrator,
to flatten the response.
What parameters are you all simulating on the secondary?
And how does it scale?? ^_^
See you at the Thon!
--
-GL
www.lod.org
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Maintainer Paul Nicholson, paul@abelian.demon.co.uk.