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RE: rectifying



Some comments FWIW:


> Original Poster: "William Parn" <parn-at-fgm-dot-com> 
> 
> 
> Greetings,
> 
> > -----Original Message-----
> > From: Tesla List [mailto:tesla-at-pupman-dot-com]
> > Sent: Wednesday, March 08, 2000 8:57 AM
> > To: tesla-at-pupman-dot-com
> > Subject: rectifying
> >
> >
> > Original Poster: "Jan Florian Wagner" <jwagner-at-cc.hut.fi>
> >
> > Hi,
> >
> > I found a very compact 3kV 50mA NST, and thought about turning this into a
> > fixed voltage (but non-regulated) DC HV power supply. I've a bunch of 5kV
> > 40mA diodes waiting that should do the rectifying and voltage doubling
> > part. But I've no clue how to do a cheap _HV_ rectifier... so I'd be
> > grateful for any advice or schematics, or web site tips!
> >
> > The DC PSU would be connected to charge up a 8nF tank cap. What size
> > should the smoothing cap be then? Does around 100uF sound reasonable?
> > Less, larger?
> >
> > And, the problem is, how can I get 100uF or other at 2x4kVDC? And what
> > type of cap would be ok?
> > Is it a good idea to put ordinary "high" voltage electrolytic caps in
> > series? Or AC motor starter caps perhaps?
> >
> > Other thing, does anyone know of a solution for this:
> >  1) even while the SG is ignited, the smoothing cap should be charged up.
> >     And not be shorted out and discharged into the short.
> >  2) when the SG quenches, there should be no limiting resistor
> >     between the 8nF tank cap and the smoothing cap. I'd want the
> >     8nF cap to be charged up fast.
> > Any way to do this?
> >
> > Many thanks!
> >
> > --
> > *************************************************
> >  Jan Florian Wagner
> >  http://www.hut.fi/~jwagner
> >
> >
> >
> 
> I am not quite sure what you are using the power supply for
> however if you are wanting to use it in a TC then no smoothing
> cap is necessary.
> 
> Do you want a full wave bridged rectifier?
> 
> 4.24KV
> This will give you both a positive and negative terminal
> to work with, however takes twice the diodes.  It also
> will give you roughly twice the overall power, because
> you will benefit from both the negative and positive side
> of the AC wave.  This I have not tried with a TC yet, only
> because I don't have the other two diodes yet.
> 
>      0------>|------------------- terminal 2
>       \                         |
>        \----|<-----             |
> NST               | terminal 1  |
>        /----|<-----             |
>      0 \                        |
>         \--->|-------------------
> 
> 
> Or are you looking for a (half wave)/full wave rectifier?
> 
> 2.12KV
> Not sure if this is called a half wave, or a full wave
> without the bridge part.  However this one takes less
> parts but wastes half of the sine wave.
> 
> 
>      ---->|---------/- terminal   2.12KV
> NST                /
>      ---->|-------/
> 
> You then need to pull a ground from somewhere, I have
> just used earth ground for this and it works.  I hook
> one side of my cap up to earth ground and the other side
> up to the dioded NST.  Fires the TC just fine.

I'd strongly advise using the secondary centre-tap with the full wave 
centre tapped supply just mentioned. It does make use of both half 
cycles but delivers only half the voltage of the full wave bridge 
arrangement. Not as efficient since it doesn't deliver any more 
current.

Regards,
Malcolm

> ---------------------
> If you are building a voltage doubler then there is some
> more parts to add.  Can you tell us what you are trying
> to power.
> 
> It is kind of tough trying to draw schematic in ASCII (barf).
> It probably is even tougher to read.
> 
> By the way you will need to parallel each of the diodes in
> the schematic with the diodes that you have.  Probably wouldn't
> hurt to use three in parallel for each diode in the schematic.
> One thing I like about a DC TC is that it sort of
> protects your NST without a protection circuit.
> 
> Hope this helps,
> Cheers,
> Bill Parn
> 
>