RE: RE: Cap question (was H bridge RSG)

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

Original poster: "David Dean by way of Terry Fritz <twftesla-at-qwest-dot-net>" <deano-at-corridor-dot-net>

Ah Ha!

So therein lies the confusion...What you are describing is called by some a
"half bridge", I call it a "wig wag". In that circuit the storage cap will
never see any RF or voltage reversal, so it would not have to be "pulse
duty".

later

deano

> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Sunday, May 20, 2001 8:44 PM
> To: tesla-at-pupman-dot-com
> Subject: RE: RE: Cap question (was H bridge RSG)
>
>
> Original poster: "Ray Haynes by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <ray.haynes-at-home-dot-com>
>
> I was planning on using an H-bridge RSG that alternates
> connecting the tank
> cap first to the storage cap then to the primary coil, kind of
> like a double
> pole double throw switch. The storage cap is connected only to the
> rectifiers when the RSG connects the tank to primary coil and the
> main bang
> happens. I know there will be some residual charge left on the tank after
> the main bang but if everything is set right it should be only a
> fraction of
> it's original charge. Or am I still missing something.
>
> Also the storage cap that I'm actually going to use is 16uf so it is
> actually 1600 times larger than my tank cap.
>
>
> > -----Original Message-----
> > From: Tesla list [mailto:tesla-at-pupman-dot-com]
> > Sent: Sunday, May 20, 2001 4:11 PM
> > To: tesla-at-pupman-dot-com
> > Subject: RE: Cap question (was H bridge RSG)
> >
> >
> > Original poster: "David Dean by way of Terry Fritz
> > <twftesla-at-qwest-dot-net>" <deano-at-corridor-dot-net>
> >
> > Hi Ray,
> >
> > The storage cap sees the full tank current while the gap is
> > firing. Also the
> > storage cap must appear as a short to the RF of the tank so as not to be
> > included in, or affect the tuning. Thus the requirement for a
> very low ESR
> > in the storage cap.
> >
> > Also in your example, "If Cs is 100 times larger than Ct
> > (1uf/.01uF) each Ct
> > (tank cap) charging will only drain Cs (main storage cap) 1% of it's
> > charge." is true for the first presentation when the initial
> charge in the
> > tank cap is 0, however at the end when the gap quenches due to the
> > equalization of the voltages on the tank cap and the storage cap, the
> > voltage on the tank cap is equal and opposite in polarity to that of the
> > storage cap upon the next presentation. That makes the voltage to be
> > processed twice as much, and the energy transferred from the
> > storage cap to
> > the tank cap four times as much.
> >
> > later
> >
> > deano
> >
> > >
> > > Original poster: "Ray Haynes by way of Terry Fritz
> > > <twftesla-at-qwest-dot-net>" <ray.haynes-at-home-dot-com>
> > >
> > > I don't understand LR's comment about needing a "largish storage
> > > capacitor,
> > > also rated for RF; and the huge voltage reversals, probably +2V
> > > to -2V (I'm
> > > assuming he meant +/-2KV)". I agree with the largish part but not
> > > the rest.
> > >
> > > Here's my thinking. First I make a fullwave rectified HV
> supply using a
> > > large storage cap (Cs). My tank cap (Ct) is .01uF and RSG
> with a rate of
> > > let's say 600BPS (hoping). If Cs is 100 times larger than Ct
> (1uf/.01uF)
> > > each Ct (tank cap) charging will only drain Cs (main storage cap)
> > > 1% of it's
> > > charge. And at 600BPS that Cs gets fully charged (ideally) once
> > for every
> > > five Ct charge cycles; the fullwave rectifier doubles the mains
> > > frequency to
> > > 120Hz and 600BPS/120Hz = 5. That seems to be roughly 5% ripple
> > on the main
> > > supply cap which doesn't seem to indicate a need for any RF
> > > requirements for
> > > the large storage cap. Actually my simulations show more like 2%
> > > ripple due
> > > to the fact some Ct charge cycles are provided directly by the
> > rectifiers
> > > (SG closes while mains are at a peak)
> > >
> > > Is there a flaw in my thinking?
> > >
> > > > -----Original Message-----
> > > > From: Tesla list [mailto:tesla-at-pupman-dot-com]
> > > > Sent: Saturday, May 19, 2001 8:02 PM
> > > > To: tesla-at-pupman-dot-com
> > > > Subject: Re: H bridge RSG
> > > >
> > > >
> > > > Original poster: "LWRobertson by way of Terry Fritz
> > > > <twftesla-at-qwest-dot-net>" <LWRobertson-at-email.msn-dot-com>
> > > >
> > > > Hi Ray and Steve
> > > >
> > > > A classic coil discharges at some voltage, then
> > > > the RF oscillates around zero, approximately. The
> > > > H-bridge never stops at zero, but goes straight
> > > > from +V to -V, and oscillates there, adding the
> > > > RF amplitude to the DC voltage.
> > > >
> > > > Advantages are very reliable firing, it will never
> > > > power arc, and the primary voltage is doubled,
> > > > adding some oomph. I would think it should work
> > > > well for MOT power supplies. It can be run at any
> > > > speed.
> > > >
> > > > The disadvantages are the necessity for a largish
> > > > storage capacitor, also rated for RF; and the huge
> > > > voltage reversals, probably +2V to -2V almost.
> > > >
> > > > At the moment its running on a 8 inch rotary with
> > > > a maximum of 240 BPS. I'm (slowly) getting parts together
> > > > for a 12 inch which should be good for 360 BPS,
> > > > and ultimately hope to make a 22 inch with 24
> > > > electrodes. Expensive, though.
> > > >
> > > > Its a simple enough circuit - I'll be glad to send a
> > > > schematic if you want.
> > > >
> > > > LR
> > >
> > > snip.....
> >
> >
> >
>
>
>