Re: AC vs DC and Toroid Question

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

Original poster: "robert & june heidlebaugh by way of Terry Fritz <teslalist-at-qwest-dot-net>" <rheidlebaugh-at-desertgate-dot-com>

Martin: I use both AC and DC coils The only major differance is a dc coil
requires a disconect coil in series with the power supply and the  coil-SG
to prevent power arc problems. I use a 15 T 1"dia x  6" air core coil on my
DC coils. I use 15/60 NST full wave rectifier for power with ASG. The only
differance in preformance is AC has less control and more noise. My DC coils
work well with and without toroids. My best toroid is a BEER Keg with
rounded ends. My AC coils dont work with out some toroid. I like pipe duct
with pie pan centers. With my DC coils I have full control of my PRF when I
use a triggered spark from single pop to 240 pps. My AC coils are line
frequency dependent. Both work well, I just like the conrrol of DC best. AC
requires less parts, its just a choice. DC lets me toy with it more.
     Robert  H
-- 


 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > Date: Fri, 06 Jun 2003 06:31:22 -0600
 > To: tesla-at-pupman-dot-com
 > Subject: AC vs DC  and Toroid Question
 > Resent-From: tesla-at-pupman-dot-com
 > Resent-Date: Fri, 6 Jun 2003 06:40:07 -0600
 >
 > Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>"
 > <MFRYML-at-aol-dot-com>
 >
 > Hello everyone,
 >
 > I have a relatively large secondary coil-about 2500 ft., 12.5" dia, 50" 
high.
 > Have a small (14 dia duct pipe toroid but planning a larger one.
 >
 > I have several questions, please:
 >
 > 1)  Given a .15 mfd primary capacitor, a rotary spark gap, and a set of four
 > 120v/7500v neon transformers in parallel producing 240 ma together, would
 > there be a performance difference (1) operating the system AC versus  (2)
 > rectifying the current to produce DC, and slowing the spark gap down to
 > allow the
 > capacitor to charge fully between firing ?
 >
 > I never really understood the mechanics of AC vs DC in a Tesla coil.  With
 > AC, doesn't the capacitor spend a large percentage of the time actually
 > draining
 > the charge at the point the current changes polarity.  If the gap fires, 
say,
 > 300 pps, at least 2 pulses in 5 will have the polarity change occur and have
 > little or no charge stored in the capacitor, assuming a normal sine wave 
60 hz
 > AC frequency.  Am I in left field ?
 > Since the polarity changes twice per cycle, does the reverse current flow in
 > the primary coil have the same effect on the oscillation as the forward flow
 > (like pushing a swing from the front instead of the back every second 
push) ?
 >
 > With the rectified DC, however, you only get current flow 50 % of the time.
 > The "pushes" may come less often, but they will be stronger.
 >
 > So, which gives better performance ?
 >
 > 2)  I used the Java Script TC designer to see the effect of a larger toroid
 > on frequency and hopefully spark length. Great Program !   I was 
thinking of a
 > 30" or 36" dia aluminized drain pipe toroid.  Is there a law of diminishing
 > returns here ?  Do you start to have too much (pink) discharge to the air
 > compared to the charge collection effect? I presume I would still need a
 > breakout
 > point attached.
 >
 > 3) The program also indicates a power factor correction capacitor of 291 
mfd.
 > Is this to be at 500v or is a higher voltage recommended.  Do these really
 > make a difference on transformer performance ?
 >
 > 4)  The info on toroid construction describes a metal or metallized plate in
 > the center.  Does this serve some purpose and affects performance, or 
can one
 > simply have the "plain doughnut without the hole" ?
 >
 > Thanks for reading.  I appreciate input on any of the points.
 >
 > Martin
 >
 >