Re: Magnifier Primary Capacitors - EQUIDRIVE vs. STANDARD

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com> 


Tesla was using glass dielectric caps in most of his construction.  With the
modern advent of PE and PP I think many of the negative factors are
overcome.

Dr. Resonance

Resonance Research Corporation
E11870 Shadylane Rd.
Baraboo   WI   53913
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, January 13, 2004 9:14 AM
Subject: Re: Magnifier Primary Capacitors - EQUIDRIVE vs. STANDARD


 > Original poster: David Sharpe <sccr4us-at-erols-dot-com>
 >
 > Hi Dan!
 >
 > Tesla list wrote:
 >
 >  > Original poster: dhmccauley-at-spacecatlighting-dot-com
 >  >
 >  > Ed, Richard, List,
 >  >
 >  > I have a question regarding the two most common primary capacitor
 >  > arrangments in magnifier systems.
 >  >
 >  > 1.  STANDARD - Single capacitor as most commonly used in classic tesla
coil
 >  > systems.
 >  >
 >  > 2.  EQUIDRIVE - Two capacitors used in the primary circuit.  One on
either
 >  > side of the primary and connected in series with the primary.
 >  >
 >  > I'm currently designing my system using the EQUIVDRIVE arrangment on
the
 >  > basis that the two great magnifier builders, Richard Hull and Ed
Wingate,
 >  > state this
 >  > arrangement is superior over the other arrangement.
 >  >
 >  > However, I'm not sure and can't see right away what the advantage is.
 >  >
 >  > Does anyone have the nitty gritty details of why the EQUIVDRIVE
arrangement
 >  > is superior over the STANDARD arrangement.
 >
 > Having used both topologies here are my spins on them
 > 1. Standard:
 >      PROS: - one capacitor
 >                  - self discharging _if_in_parallel_ with powering
transformer
 >      CONS: - one capacitor absorbs total stress of impulse excitation
 >
 > 2.  Equidrive
 >      PROS:  - two capacitors share voltage stress of tank circuit
 >                  -  modest tank tuning possible by "shifting" capacitor
value
 >                     of one capacitor in relation to other (realizing
smallest
 >                     capacitor sees highest voltage drop)
 >     CONS:  - DANGEROUS, e field variation while tank is being
 >                     impulse excited will result in residual charge on
 > capacitors
 >
 >                     in series.  If you touch the primary with machine off
and
 > are
 >                     touching ground at the same time ZZAAPP!!  (Guess how
 >                     I know about this...   :^C )  Caps MUST be discharged
 > either
 >
 >                     by shorting rods or resistors prior to making tune
 > adjustments
 >                     to primary.
 >                   - Two capacitors are needed at 2X single capacitor value
 >                     (series C = C/2) for a given resonant Fo.
 >
 > My guess is since Tesla was using glass capacitors at Colorado Springs,
 > the series connection allowed more voltage hold off versus a singular
 > capacitor bank.  Plus he reconnected interior high voltage windings of
 > Westinghouse Transformer from 50kV to 25kV for most of his experiments,
 > due to the fact of in masse capacitor blow ups while attempting to run
 > his magnifier at 40-50kV (refer to the CSN for further details).
 >
 > Tesla postulated that the equidrive circuit since it was symmetrical would
 > have faster drive characteristics then a single capacitor configuration.
 > I find it hard to believe that there is any significant advantage to one
 > capacitor versus the Tesla equidrive configuration, except in one
condition.
 > IF one was using very high voltage input (>30kV arbitrary), equidrive
 > would very effectively reduce voltage stress on capacitor(s), but now you
 > need (4) of a given size (2 in parallel + 2 in series) to equal a singular
 > capacitor for a given primary frequency.  Another possible advantage
 > is fine primary tune control by adjusting relative capacitor values
relative
 > to each other.
 >
 > A comparison of both circuits set to same frequency using appropriate
 > capacitor values (same construction, ESR, connections, etc.) would be
 > an excellent experiment to determine if there is any difference
 > between the two topologies...
 >
 >  >
 >  > Thanks
 >  > Dan
 >
 > Regards
 > Dave Sharpe, TCBOR/HEAS
 > Chesterfield, VA. USA
 >
 >
 >