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Inducing Voltage In Metal Object Close To A TC. Was RE: First Light at Last! (update)


Greetings,

> -----Original Message-----
> From: Tesla List [mailto:tesla@pupman.com]
> Sent: Friday, April 14, 2000 9:25 AM
> To: tesla@pupman.com
> Subject: Re: First Light at Last! (update)
> 
> 
> Original Poster: "Bert Hickman" <bert.hickman@aquila.com> 
> 
> Mark,
> 
> Not clear just why it chose to break down at the thermostat, but that
> apparently was the "weakest link" at the time. However, the point still
> remains that you're picking up enough voltage to cause breakdown in this
> circuit, either through magnetic induction from the close proximity of
> the TC primary winding, or from the near field of the TC in the wires
> going between the motor and the variac in your control box. BTW,
> near-field pickup can ALSO couple into your house wiring if you happen
> to use house wiring in the area near the coil that's not contained
> within metallic conduit, or if you have nearby large sections of
> conductive metal (such as aluminum siding) that are not grounded. Some
> coilers on this list have actually started small fires due to induced
> voltage and arcing... :^)

I have my static spark gap sitting in a 2 foot diameter by 1 foot length
of aluminum tube.  The open end is flush with my garage floor and then
I also have a metal sign on top of the other open end.  The idea was to 
help prevent RF from bugging the neighbors.  Initially I didn't have this
connected up to ground, and being as my garage floor is not as perfectly
level as the aluminum tube there are some air gaps down by the floor.  I
noticed that sparks were jumping between the concrete floor and the 
aluminum tube.  I didn't really know why so maybe what was going on
was the induced voltage from the Megnetic field of the TC.

Very interesting thanks for sharing that information, I need to 
come up with something better for containing the UV and RF of my
spark gap.

> 
> To fix your motor problem, you may want to add a couple of 600 volt (or
> better) bypass capacitors between each motor lead and the case of the
> motor to bypass induced RF around the windings, and use a similar
> approach on the controller end. Other coilers have successfully used EMI
> line filters (internally, a combination of coupled inductors and bypass
> caps) to do the same thing. Also, try wiring the motor with a pair of
> wires close together (like regular 120V. zip-cord), and also try to
> route these wires so that they are short, and at a right angle to the
> primary wiring - this should reduce the magnitude of direct inductive
> coupling from the primary. Finally, if you still have problems, you may
> need to physically increase the vertical distance between the motor and
> the TC primary above. 
> 
> Safe coilin' to you, Mark!
> -- 
> Bert Hickman
> Stoneridge Engineering
> http://www.teslamania.com
> 
> 

Cheers,
Bill Parn