Re: Magnifier Primary Capacitors - EQUIDRIVE vs. STANDARD

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

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi D.C.,

At 09:56 AM 1/12/2004, you wrote:

>A proposed experiment for active members of this list:

I think a few of us have already "been there, done that" :o)))



>In all the coils we have built we have never (in over 45 years) seen any
>charge remaining on a cap operating in an AC tank circuit.  I know Ed and
>others have reported that charge does remain with an equa-drive system, but
>with the standard classic configuration I have never seen any residual
>charge whatsoever.

MMCs are strung together much like the equidrive system.


>We operate a coil and we are tuning it and after shutdown we adjust the
>tuning tap and adjust the sparkgap usually within 60 seconds and we have
>never received an electric shock in any manner.  In theory, if you shut off
>the coil at the exact AC peak, you should have some charge left but we have
>never encountered any charge.

Normally, the two outside cap terminals will be discharged back through the 
transformer.  "Normally" it will discharge.  You build really nice coils 
that do not do abnormal things, but I am not sure all of us do ;-))


>I've often wondered why everyone goes through all the trouble of soldering
>all those resistors across the MMC caps.  I've never done this and we have
>never found an MMC that retains charge on an AC circuit.  I've been using
>MMC circuits for approx 3 yrs, and again, no residual charge remains.

They have shocked "me"....  The outside higher voltage caps tend to corona 
more causing a net DC current flow.  This tends to cause unequal voltage 
build up across the string.  Shorting the outside terminals will certainly 
drop the "sum" of the cap voltages to zero but they my be charged like this:

0
500
1000
2000
-2000
-1000
-500
0

The sum voltage is zero for the outside terminals, but don't go playing 
with the individual caps!!  Guess how I know this :o)))


>If you are running DC in your system, then, of course, there will be
>residual charge on the cap.
>
>Other members of this list might wish to  verify this with volt meters on
>their systems.  I would be curious to know the results.  It would sure save
>a lot of construction time with the resistors.  We never use them except on
>DC circuits with Marx generators, etc.

Might not be a good idea unless the meter can take a few thousand 
volts!!  I have had charged MMC caps sitting for days that were still 
easily able to knock one's socks off!!  Worse yet, after they are 
discharged, they can again build up a charge due to that effect whose name 
I can't remember at the moment....  With a resistor across them, they are 
dead as a door nail...


>I've worked with Bill Wysock tuning a large coil (16 ft. spark length) and
>he also never discharged the caps prior to making primary tuning
>adjustments.  We were even working directly on a 0.2 MFD cap within 60
>seconds of full power operation and no charge remained.

The charge is being blead off though the charging circuit or the spinning 
rotary gap knocks it down.  Or, Bill is just really tough ;-))  In his 
case, he knows his coils well enough to trust them.  I do that too, but I 
have the bleeder resistors there so there are three things to knock the 
voltage out before it knocks me out.  For most of us, best to use resistors 
and such to be super safe.


>Terry F. with his HV probe on a TEK scope could leave the probe across some
>MMC's and then shut the coil off.  I'm betting after 60 sec he sees nothing
>or a value less than 60 Volts.  It has never shocked us so it has to be very
>low if any remains.

I could remove the resistors, short to two ends of the MMC to ground, and 
charge the center to 15kV.... and then send it to you to test 
yourself  >:o))))   I could also send you one just like it with the 
resistors in place.  You see the difference?  ;-))  The real problem is 
that the inside of the MMC can be touched too where goodness only knows 
what charges may be waiting!

Cheers,

         Terry


>Dr. Resonance
>
>Resonance Research Corporation
>E11870 Shadylane Rd.
>Baraboo   WI   53913
> >
> > Electrically and performance-wise, two caps in series, no matter if
> > separated by the TC primary or back to back, act like a single cap with
> > twice the voltage rating and half the capacitance of a single cap.  But
> > esthetically, it has some appeal for those who value symmetry and
>scientific
> > names to describe their setup.  One could argue two caps might help
>isolate
> > the primary from the 60 Hz power source, but the equidrive setup is
>probably
> > just as potentially lethal to the careless person who contacts a primary
> > while the coil is in operation as is a single cap configuration.
> > --Steve Y.