marv h. gonsior wrote:
>
> Hello All,
>
> I've been following all the p.s. comments and data with interest and
> appreciation. It appears to me that possibly no one has mentioned or
> measured the secondary d.c. resistance.
That's part of the supply ESR, as is primary resistance (transformed by the
turns
ratio), core loss, capacitor series resistance, and flux leakage.
> On the subject of the chokes. Henry and Collins used to capacitatively
> resonate them for 120 Hz and that would give the appearance of
> excellent regulation since the peak charging wasn't there. It worked
> great BUT, you have to use a BIG resonating cap to handle the
> circulating current; i.e., at least 2X the d.c. voltage of the p.s.
> Years ago, I used just such a set up and it was vfb. Now, it's just a
> big cap to do the job! Anyway, gang, there's just no substitue for size
> or another way of stating it that "there just isn't any free beer!"
A word of caution on this. If you place the parallel L/C choke system
exactly at resonance, the choke and capacitor can become part of a large energy
storage tank circuit. It can MULTIPLY the charging voltage by the Q of the choke
and capacitor's resonant circuit, and you can wind up with many kV of extra
voltage.
I use this "trick" to build hi-pot machines, and can get 20 kV from a 200 volt
transformer driving a rectifier driving a resonant choke!
A resonant filter driven directly from a rectifier is a VERY dangerous circuit
to play with!!!!!!!!!
Any time a resonant choke is used ALWAYS protect the supply with a gap or other
votage limiting device across the choke, and NEVER tune the choke exactly to
resonance. Always tune it at least 20% high of resonance.
73, Tom
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