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From: Johnny Boy on 2 Oct 2006 00:02

"Robert Baer" <robertbaer(a)earthlink.net> wrote in message
news:PV%Tg.1793$Lv3.1448(a)newsread1.news.pas.earthlink.net...
> Johnny Boy wrote:
> > "Robert Baer" <robertbaer(a)earthlink.net> wrote in message
> > news:IsMTg.1351$Lv3.343(a)newsread1.news.pas.earthlink.net...
> >
> >>Johnny Boy wrote:
> >>
> >>
> >>>"Robert Baer" <robertbaer(a)earthlink.net> wrote in message
> >>>news:fplTg.3005$Y24.2825(a)newsread4.news.pas.earthlink.net...
> >>>
> >>>
> >>>>Johnny Boy wrote:
> >>>>
> >>>>
> >>>>
> >>>>>"Robert Baer" <robertbaer(a)earthlink.net> wrote in message
> >>>>>news:nb3Tg.363$Lv3.147(a)newsread1.news.pas.earthlink.net...
> >>>>>
> >>>>><snip>
> >>>>>
> >>>>>> That might help; how does one specify Vhigh and Trise for A1?
> >>>>>> I was also wondering abuut a power supply for the inverter, but
> >
> > since
> >
> >>>>>>this is an emulator, maybe one does not need to be specified?
> >>>>>
> >>>>><snip>
> >>>>>
> >>>>>Don't know about the inverter supply, but for Vhigh/low and
Trise/fall,
> >>>>>right-click the inverter, then copy the following into the
"SpiceLine"
> >>>>>attribute, (edit to suit).:-
> >>>>>
> >>>>>Vhigh=12 Vlow=0 Trise=100n Tfall=100n Td=100n
> >>>>>
> >>>>>(Thanks to DNA - I found this in his alternative to your circuit.)
> >>>>>
> >>>>>When I first ran this simulation, I got the same error as you, but
> >
> > after
> >
> >>>>>adding the above line to the inverter attributes, I get a different
> >>>
> >>>error:-
> >>>
> >>>
> >>>>>Fatal Error: Singular matrix: check nodes n013 and u1:1:va+
> >>>>> Iteration No. 2
> >>>>>
> >>>>>
> >>>>>... Johnny
> >>>>>
> >>>>>
> >>>>
> >>>> That circuit he gave is strange:
> >>>>1) "Rl" is not from output to ground, where a practical load would go.
> >>>>2) R1 allows Vout to go to 1.2KV with a small ripple; without Rl, the
> >>>>output only goes to 500V with a lot of ripple.
> >>>>3) Increasing Rf by a factor of 5 has no effect on output voltage.
> >>>
> >>>
> >>>This surprises me - when I manually calculate feedback with the given
> >>>values, the feedback voltage to the inverters is 2.5V as it should be
> >
> > for
> >
> >>>1kV output. The ripple is determined by the current limit via the 100R
> >>>resistor.
> >>>
> >>>
> >>>
> >>>>4) Output voltage ramps up in a *linear* fashion.
> >>>
> >>>
> >>>Shouldn't it do this?
> >>>
> >>>
> >>>
> >>>>5) Have not found what limits/controls the output voltage.
> >>>
> >>>
> >>>See my reply to >3)
> >>>
> >>>
> >>>
> >>>>6) M1 operates in the linear mode, but "switches between two current
> >>>
> >>>levels.
> >>>
> >>>
> >>>>7) Looks like the output could be in the 10KV region with minor mods
> >>>>(*not* changing the multiplier).
> >>>
> >>>
> >>>
> >>>I should point out that I'm a complete novice to LTSpice, with 2 days
> >>>experience.
> >>>Perhaps you should try posting this problem to the Yahoo LTSpice group.
> >>>
> >>>... Johnny
> >>>
> >>>
> >>>
> >>
> >>...and *where* does that "2.5V" value come from?????
> >
> >
> > (1.2kV/(48M + 100K + 1K)) * 101K = 2.5V
> >
> >
> >
> >> Oh, i forgot one other strange item: the lines / wires on the diodes
> >>are *not* at right angles!
> >> How the &#$()#$ was that done???
> >
> >
> > Dunno - ask DNA (Genome)
> >
> > ... Johnny
> >
> >
> I ment, where is that 2.5V reference?

Right, sorry, I misunderstood and thought that you meant from a feedback
point of view. The 2.5V reference is the half-way point of the Vhigh and
Vlow of the (first) inverter, A1. ie Vhigh=5V and Vlow=0V, so Vthresh =
2.5V.
I'm surprised that Genome has deserted the thread, after putting so much
time into the alternative schematic.
Incidentally, my calculation was slightly out. If A3 is low, the 1K
resistor is not in the equation. Not much difference, though, it's still
near enogh to 2.5V of feedback at 1.2kV output.

.... Johnny


From: Genome on 2 Oct 2006 12:18

"Robert Baer" <robertbaer(a)earthlink.net> wrote in message
news:nW%Tg.1794$Lv3.543(a)newsread1.news.pas.earthlink.net...
> Johnny Boy wrote:
>
>> "Robert Baer" <robertbaer(a)earthlink.net> wrote in message
>> news:IsMTg.1351$Lv3.343(a)newsread1.news.pas.earthlink.net...
>>
>>
>>> Oh, i forgot one other strange item: the lines / wires on the diodes
>>>are *not* at right angles!
>>> How the &#$()#$ was that done???
>>
>>
>> I just had a go at this - if you first place a line, then drag the end of
>> it, it's not hard to make it 45 degrees instead of 90. (That's how the
>> &#$()#$ it was done, I guess)
>>
>> ... Johnny
>>
>>
> Ahhh....
> Thanks!

Yes!!!!!!!, me too.... ignore my other one.

DNA


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