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Re: Hvguy-dot-com Feedback SSTC and New Stuff!!!
Original poster: "Jolyon Vater Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
Ken,
So is the reason why it will not work because of the fact that there is no
bias to keep the base-emitter junctions conducting -and therefore the
transistors cannot work as linear amplifiers?
Would biasing resistors suffice to get the thing started?
Jolyon.
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, November 15, 2002 1:13 AM
Subject: Re: Hvguy-dot-com Feedback SSTC and New Stuff!!!
> Original poster: "K. C. Herrick by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <kchdlh-at-juno-dot-com>
>
> Jolyon-
>
> I believe I see what you are getting at...but it won't work. You need a
> linear amplifier directly following the network in the return-circuit of
> the secondary. The signal there is no more than noise initially, then
> increases to only ~+/- 0.7 V because of the diodes. You want the diodes
so
> as to limit the voltage excursion when the oscillations build up. For
that
> amplifier, I just use 3 CMOS gates "linearized" with ~100 K feedback
> resistors and capacitor-coupled. The 3 must be in two ICs, not just one,
> to avoid deleterious substrate-coupling. The output of the 3rd one will
be
> pretty much a 5 V square wave all the time. Circuit noise in that
> amplifier chain should be sufficient to get things started.
>
> You could use, perhaps more efficiently, a single op-amp to drive the
> following logic-level gates.
>
> The next CMOS gate in the line will provide a firm square wave, and then
> one more can be used, with a switch, to select the correct
> positive-feedback phase for the subsequent stages.
>
> Ken Herrick
>
> On Thu, 14 Nov 2002 08:01:34 -0700 "Tesla list"
> <<mailto:tesla-at-pupman-dot-com>tesla-at-pupman-dot-com> writes:
> > Original poster: "Jolyon Vater Cox by way of Terry Fritz
> > <<mailto:twftesla-at-qwest-dot-net>twftesla-at-qwest-dot-net>"
> <<mailto:jolyon-at-vatercox.freeserve.co.uk>jolyon-at-vatercox.freeserve.co.uk>
> >
> > Ken,
> > With regard to common base circuit reconfigured slightly to include
> > a 1k
> > resistor
> > would this work if Phases 1 & 2 instead of being used to drive the
> > fets
> > directly were used to drive an amplifier which would drive
> > the fets say, via a pulse transformer?
> >
> > +ve supply rail
> > > > |
> > > > R1
> > > > |
> > > > +-------Phase 1
> > > > c |
> > > > \
> > > > NPN |---------GND
> > > > e /
> > > > sec |
> > > > | |
> > > > +--1K----+
> > > > | |
> > > > c1 e \
> > > > | PNP |----------GND
> > > > | c /
> > > > | |
> > > > +---------------------GND
> > > > |
> > > > +----------Phase 2
> > > > |
> > > > R2
> > > > |
> > > > -ve supply rail
> >
> >
> >
> >
> >
> > (The circuit I have shown is basically a non-inverting
> > voltage amplifier. The emitter-base junctions of the NPN
> > and PNP transistors act in the same way as the
> > back-to-back diodes in the setup you described -switching
> > on the respective transistors whenever voltage across
> > them goes above and below 0.6 volts, positive or negative
> > of ground)
> >
> > Jolyon.
> >
> >
> > ----- Original Message -----
> > From: "Tesla list" <<mailto:tesla-at-pupman-dot-com>tesla-at-pupman-dot-com>
> > To: <<mailto:tesla-at-pupman-dot-com>tesla-at-pupman-dot-com>
> > Sent: Thursday, November 14, 2002 1:58 AM
> > Subject: Re: Hvguy-dot-com Feedback SSTC and New Stuff!!!
> >
> >
> >
> >
>
>
>
>