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Re: flyback TC
On Sat, 16 Oct 1999 12:17:22 -0600 Tesla List <tesla-at-pupman-dot-com> writes:
> Original Poster: "Jim Lux" <jimlux-at-jpl.nasa.gov>
>
> > 3. Ihave calculated the output of a cascade multiplier with 60
> stages to
> > be at least 6kv and 60ma(1kv drop). Is there any reason for this
> not
> > working for a TC?
Is should of said about 6kv, 60 ma and 1kv drop actually.
>
> 60 stages? Running off 110V input to get 6 kV, presumably. Did you
> take
> into account the forward voltage drop and IR losses of the
> rectifiers.
Yes, I did
It
> is quite difficult to get a 60 stage multiplier to work. The
> frequency will
> need to be quite high
I did the calculations at 60hz, but I might try to boost the frequency to
a few khz if this works at 60.
to get 60 mA out, or the caps will need to be
> fairly
> large.
I was looking at 10uf
Don't forget that the current in the caps on a multiplier
> stack is
> significant (well at least 60 mA average, in your case, and much
> higher
> peak, particularly at the top stages).
>
> However, if you have lots of spare time to do the assembly
Spare time is a commodity in great abundance at the moment.
and
> you've got
> the caps and diodes, it is worth a try.
>
> I assume you'd you running an resonant charging scheme with an
> inductor and
> a diode to charge the tank cap? Don't forget it takes many, many
> cycles of
> the input for a multiplier to reach nominal output voltage (on the
> order of
> 2N cycles for a half wave multiplier)
>
> Just from a construction complexity standpoint, you are probably
> better off
> finding a surplus HV transformer. Cost is an issue too, 1N4004's
> would work
> for the diodes and be cheap (for running off 60 Hz), but the caps
> might not
> (of course, you could use surplus photoflash caps from disposable
> cameras,
> which you can get for free)
I would be using 1n4007's for 2 cents each from Jameco. About 200 of
them with a few in parallel on the first stages because they have a
higher duty cycle. The capacitor's are 20 cents each, 10uf, 105C from
Mouser.
Yeah, you are right about a HV transformer being cheaper, but I thought
this would be a good learning experience. It was sort of just a flash of
inspiration.
So is there any reason this would not work? Has anybody tried this
before?
I am using the calculation: Vd= I*N/2*pi*f*c
Is this formula correct?
Bryan
>
>
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