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

["Tesla list" <tesla@xxxxxxxxxx>]

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.
>  >
>  >
>
>
>
>