Re: ARSG with DC power

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

Original poster: "Kevin Ottalini by way of Terry Fritz <twftesla-at-uswest-dot-net>" <ottalini-at-mindspring-dot-com>

J.B.:
	I wouldn't recommend running a doubler with 0.2ufd caps.
As you can see from the first worksheet below, indeed the ripple
is way beyond the target output voltage ... which just means
that the caps can't carry the full load at 60hz.  Given the
nature of ASRG and slow rep rates though it might work for a
while, but I was unsuccessful with a doubler with similar
values.

If you are already using two MOTs to get to 5500vac, then
you have a difficult time ahead (if you need 11kv).  The
only three easy fixes are:
1. Get larger caps (3000v AC rated caps)
    a.  2.0ufd gives 2.5kv ripple at 60Hz and
    b. 10.0ufd gives 500v ripple at 60Hz

2. Increase the frequency of operation.
   As you can see from the second worksheet below, 20KHz
   operation gives you only 75v ripple.  You can also
   increase the number of stages as well for more voltage.

3. Convert to a simple fullwave rectifier and run at the
   rectified RMS of the two transformers.  You don't need
   caps at all for this configuration.  The tank cap will
   do all the filtering that is necessary.  This will also
   let you upgrade to a NST or other transformer at a later
   date.

You also need a series limiter resistor (or inductor) on
the output of the rectifier to keep the current surges
from exceeding the peak current of your diodes.  Start
with 5kohms or 10kohms and work down from there.

In any case, but be sure to have good solid ground returns
for the primary side, and take care to isolate the ground
return for your secondary.  Rectifiers puncture easily.  In
fact, I would recommend a solid 2X over voltage (use at least
two diodes in series instead of just one).

Best,
	Kevin

<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
Original 0.2ufd caps:
=====================	
Cockroft-Walton Multiplier Work Sheet
-------------------------------------
November 6,1998 K.Ottalini
-------------------------------------
            Enter the number of stages:? 2
       Enter the input voltage (volts):? 5500
     Enter the input AC Frequency (Hz):? 60
       Enter the capacitor values (Uf):? .2
  Enter the load current (amps) or 'R':? .100
-------------------------------------------------------
      The estimated ripple at  100 ma is:  25 KVolts      <---- wow!
                 The output voltage is:  11 KVolts
               The estimated ripple is:  113.6364 % max at this current.
                The estimated Vdrop is:  58.33334 KVolts  <---- and wow!
            The real output voltage is: -47.33334 KVolts  <---- beyond wow!
             The percent regulation is:  265.1515 %
The power requirement for  11 KVolts at  100  ma is: 1100 Watts
       This is equivalent to a load resistance of  110000  Ohms

*---------------------------------------------------------------------------
-*
Higher Frequency
================
Cockroft-Walton Multiplier Work Sheet
-------------------------------------
November 6,1998 K.Ottalini
-------------------------------------
            Enter the number of stages:? 2
       Enter the input voltage (volts):? 5500
     Enter the input AC Frequency (Hz):? 20000
       Enter the capacitor values (Uf):? .2
  Enter the load current (amps) or 'R':? .100
-------------------------------------------------------
      The estimated ripple at  100 ma is:  .075 KVolts  <--- ok
                 The output voltage is:  11 KVolts
               The estimated ripple is:  .3409091 % max at this current.
                The estimated Vdrop is:  .175 KVolts    <--- ok
            The real output voltage is:  10.825 KVolts  <--- ok
             The percent regulation is:  .7954546 %
The power requirement for  11 KVolts at  100  ma is: 1100 Watts
       This is equivalent to a load resistance of  110000  Ohms

----------
> From: Tesla list <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: ARSG with DC power
> Date: Sunday, December 17, 2000 8:01 PM
> 
> Original poster: "J. B. Weazle McCreath by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <weazle-at-hurontel.on.ca>
> 
> 
> Hello Coilers,
> 
> Being unable to work on/run my coil due to my unheated shop, I've been
> busying myself with planning upgrades for it.  One notion is to build
> up a full wave voltage doubler circuit using a pair of MOT's and have
> it supply DC at around 11 KV to an asynchronous rotary gap.  I'm a bit
> concerned about the ripple on the D.C. output of the supply.  Since it
> won't be filtered much by the doubler caps (0.2 uF. total), will that
> have an effect on the gap operation?  I'll have a R/C filter of Terry's
> design between the voltage doubler and the gap.  WinTesla tells me the
> coils operating frequency will be around 240 kHz.  Comments and ideas
> are welcome to get me through the freezing in the dark of a Canadian
> winter!
> 
> 
> 73, Weazle, VE3EAR/VE3WZL
> 
> Listening: 147.030+ and 442.075+
> E-mail:    weazle-at-hurontel.on.ca
>            or ve3ear-at-rac.ca
> Web site:  www.hurontel.on.ca/~weazle
> 
>