RE: DC coil without the voltage doubler resoance charge inductor?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>

HI ALL, I am having a hard time understanding how Mot's with out a lot of
series paralleling to contain the inductance on target can withstand the
torture of the high current demand and 30KV voltage doubling + from my pole
pig power. It seems to me that a similar choke would need to be constructed
consistent to a pig sans LV and even better insulated, constructed, and
rated HV windings. This Steve does not take into consideration your spdt gap
but rather the Burnett configuration. I plan to try both. Am I missing
something here? Smoking the choke seems like a very bad outcome...and a run
away condition. Poof. Any other ideas on limiting the charge from the filter
caps to the tank?

Thanks for the educating posts.
Jim Mora, Resistor naysayer
Ojai,ca

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Thursday, May 05, 2005 8:47 PM
To: tesla@xxxxxxxxxx
Subject: Re: DC coil without the voltage doubler resoance charge inductor?

Original poster: "S&JY" <youngsters@xxxxxxxxxxxxxxx>

Paul,

I'm not Mark, but I believe the inductance of your NST will be so high that
you will not be able to fully charge your primary cap except at very low
break rates.  I have used 4 MOT secondaries in series as a charging reactor
with no problems with breakdown.  The MOTs need to be mounted on insulators
and separated from each other, of course.

--Steve Y.
----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Thursday, May 05, 2005 5:31 PM
Subject: Re: DC coil without the voltage doubler resoance charge inductor?


 > Original poster: "Paul B. Brodie" <pbbrodie@xxxxxxxxxxxxx>
 >
 > Mark,
 > I have been considering duplicating your DC resonant charging
configuration
 > and have most of the parts required minus the charging reactor. I was
 > considering using the secondary of a 15kV NST for this but after reading
 > about your experience with the MOT secondary burning out, I have second
 > thoughts. I do realize that the NST secondary is designed for 15kV vs.
the
 > 2000kV of a MOT. What is your opinion about this idea? Thanks.
 > Paul
 > PS Your previous emails and your web site have been extremely helpful.
 > Thanks again.
 >
 > ----- Original Message -----
 > From: "Tesla list" <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>
 > To: <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>
 > Sent: Thursday, May 05, 2005 1:21 PM
 > Subject: RE: DC coil without the voltage doubler resoance charge
inductor?
 >
 >  > Original poster: "Mark Dunn"
<<mailto:mdunn@xxxxxxxxxxxx>mdunn@xxxxxxxxxxxx>
 >  >
 >  >
 >  > Jim:
 >  >
 >  > I use a DC system with great success.  I have a homemade 31 H charging
 >  > reactor built on a gapped U-100 Ferrite core in series with the d-q
 >  > diode.  Orignally, I used two MOT secondaries in series(15 H ea) but
 >  > eventually the insulation breaks down on the secondary wire and arcs
 >  > over in the secondary causing the inductance to drop.
 >  >
 >  > I used 1N5408 diodes in series to create the d-q and F-W rectifier(4
 >  > groups obviously).  Each diode is parallelel with a 1.2 megOhm
resistor
 >  > and 1 nF ceramic disk snubber cap(I built these boards a couple years
 >  > ago so I'd have to dig out the math if you want to know how I arrived
at
 >  > those values-I know the resistor was picked because I could get a bag
of
 >  > 200 for $5). My rectifier/power supply design produces + and - DC legs
 >  > and I have a series of caps to give me 1.5 uF of filtering(reduce
 >  > ripple) between each DC leg and ground.
 >  > The filter caps are a series of cheap 450volt electrolytics.  These
are
 >  > also paralleled by 1.2 mOhm resistors for bleed down.
 >  >
 >  > I think you need the charging reactor(CR) so that the rectifier does
not
 >  > see a dead short when the spark gap is firing.  The CR protects the
 >  > rectifier because it makes current lag voltage, but that is obvious.
 >  > Secondly, it protects the rectifier from the RF as you pointed out,
but
 >  > you have a plan to stop that problem(I think - I have no input for you
 >  > on you RF choke design concept).  The additional feature of the CR to
 >  > double voltage is not an issue for you.  By the way, I have the CR on
 >  > the + DC leg.  I always have wondered what protects the -DC leg.
 >  > Assumed it was because there was no current flow, but RF is always
 >  > "looking" for ground.
 >  >
 >  > Please note I am operating at lower voltages than you.  I am using a
 >  > series of MOT's to produce (2) 3500 VAC legs 180 deg out of phase(net
 >  > 7000 VAC.  After the rectifier I have (2) DC legs, one at +5000 VDC
and
 >  > the other at -5000 VDC.  Thus, my Vrrm is only 11,000 volts due to the
 >  > center tapped type design.  Each of my diode strings is thus only (12)
 >  > diodes. I did use a (20) diode string for the d-q.
 >  >
 >  > Mark
 >  >
 >  >
 >  >
 >  > Original poster: "Jim Mora"
<<mailto:jmora@xxxxxxxxxxx>jmora@xxxxxxxxxxx>
 >  >
 >  >
 >  > Hello all,
 >  > DC Coil: I have acquired all the parts and am in various construction
 >  > phases of the 11" linear variable rotor 0-500bps spark gap, safety
 >  > resister banks (tiger strip network) 3 min bleed down from a 4Uf 20KV
 >  > Maxwell filter/ smoothing cap. 100k 150 watt safety Bang fiberglass
 >  > stick. I will short and ground this before I go down stream!
 >  >
 >  > After pounding my head I see no advantage to a HV charge inductor as I
 >  > am able to deliver 20365v @ 8k watts easily with my pig 14400 5kva
 >  > (harder to come by in UK I guess) (in a 10KVA tank)Ultimately, I would
 >  > like to charge ~ 80nf with up to X^limit? bps and in the 8kva ball
park.
 >  >
 >  > The charge inductor seems to be a source of failure for many who have
 >  > gone down this road? I am thinking of retaining my welder and
ballasting
 >  > the LV side of the pig.
 >  >
 >  > **A few design questions?*** The FW Bridge will be made from  4 stacks
 >  > of(6)studded 7.5KV each 4.5a diodes part # hvca hdb7.5 9928
(Altronics).
 >  > These should all have a snubber across them yes? Suggested value, type
?
 >  >
 >  > I have a (100) 1N5408 1000v 3or 4 amp doides I was thinking of
 >  > paralleling 2 and series 40 pairs of these as d-Q is a one nano
snubber
 >  > across each pair prudent?
 >  >
 >  > Lastly the RF coming back from the tank to reek havoc and pillage the
 >  > rectifiers. Searching the achieves, "a simple 1"x 6" open air coil of
 >  > house wire should act as block" or HV wire wound on a Large torrid
such
 >  > as a TV deflection coil?" Are we buying this? I would appreciate some
 >  > guidance folks.
 >  >
 >  > Thanks Much
 >  > Jim Mora
 >  > Ojai, Ca.
 >  >
 >  >
 >
 >
 >
 >