Original poster: Steve Conner <steve@xxxxxxxxxxxx>
Hi Paul, all,
I would go one step further and say that anyone tuning a magnifier
empirically would end up avoiding that condition by a country mile.
If the entire output voltage appears across the extra coil at any
time, then the extra coil would flash over before the system reaches
the maximum "Watts number" it would be capable of with a tuning that
gave a more even voltage gradient along both coils. So I believe
Richard Hull's magnifier couldn't have been "correctly" tuned and
would have self-destructed spectacularly if it was.
My own current belief is that as long as you make the characteristic
impedance of the resonator anywhere between 50,000 and 150,000 ohms,
the coil will perform well. I used 50,000 for my last DRSSTC and it
has produced sparks 4.3 times the length of its secondary.
If I was constructing a magnifier I would make the secondary and
tertiary of more or less the same diameter and wire gauge. To all
intents and p urposes I would be taking a 2-coil system and cutting
the secondary in two pieces. I would also use a DRSSTC driver to
excite one of the two lower frequency modes, where the secondary and
tertiary resonate together almost as if they were a single coil, and
avoid the higher frequency mode that (AFAICS) generates a lot of
voltage on the transmission line without contributing much to the output.
I would also minimize the transmission line capacitance to keep this
unwanted mode as far in frequency from the wanted one as possible.
The idea would be to distribute the voltage evenly across the whole
coil system and so get the highest output voltage before flashover.
Steve
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Probably true for most magnifiers. But if the system is tuned
corre ctly for 'complete' energy transfer, the entire output voltage
will appear momentarily across the 3rd coil: peak topvolts is tuned
to occur at the same instant that the transmission line voltage is
momentarily zero. That state of affairs is very unlikely to
happen except by very careful design and tuning, so Steve's comment
is fair.