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Discharging Capacitor


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From:  Esondrmn-at-aol-dot-com [SMTP:Esondrmn-at-aol-dot-com]
Sent:  Thursday, February 05, 1998 4:36 PM
To:  tesla-at-pupman-dot-com
Subject:  Re: Discharging Capacitor

In a message dated 98-02-04 13:42:44 EST, you write:

<< Hello all:
 
 In order to adjust the primary coil after the TC has been running, one
 would prefer to discharge the capacitor(s) to eliminate the chance of
 becoming a human wire.  I was wondering how others have accomplished
 this without damaging anything.
 
 I am building a TC for the Physics Dept. here, and I have to add safety
 measures throughout the TC design in order to prevent any accidents from
 happening.  You see, the physics instructors will be using the TC for
 demonstrations on magnetic fields, and who knows what instructors might
 do.  So I figured I could use a solenoid to throw a contact, which goes
 through high resistance resistors (I have several hollow ceramic
 resistors rated at 100000 Ohms at 200W, generously given to me by the
 Dept.).  I could series the resistors to get a current flow in the order
 of milliamps, which would work.  But this is just one idea.
 
 Oh, I have also seen boxes of old vacuum tubes in the E&M lab at the
 university, and was wondering what are the most common tubes used in
 Tesla work? (There's about a hundred different tubes just sitting
 there.)  I'm sure they would sell them cheap if any are suitable for TC
 work.
 
 Practicing Safe Coiling in Wisconsin
 Patrick Gustafson >>

Patrick,

I am not sure I would want any extra wires connected to the tank circuit and
going anywhere else.  It will cause off axis inductance losses and possibly
corona losses.  You will also have a problem keeping the relay or whatever is
used from arcing over during coil operation.  If your coil only uses one tank
capacitor, when you shut down the power, the capacitor will discharge through
the primary coil and back to the transformer.  The secondary windings of the
high voltage transformer will quickly discharge the cap.  If you use and equi-
drive coil where there is one capacitor in series with each HV lead, then you
will need to discharge the caps when moving the tap on the primary - and
probably every time you shut it off.

Ed Sonderman