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Re: Do TCs need AC or DC?



Original poster: "Kevin Ottalini by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ottalini-at-mindspring-dot-com>

Neil:
        Not stupid at all ... very good!  TCs can run off of low-frequency
AC
or DC depending on a few minor design changes.

For the most part,  running off of AC is little less expensive but a little
trickier
in that you need to have a spark gap with good timing, a little more
protection
(safety gaps) and for medium and higher power setups you need a way to
limit the power from the mains (ballasting)

Running a TC off DC cost more since usually you need some high voltage
diodes and some resistors (or inductor) and preferably a rotary spark gap
(RSG), but you don't need safety gaps or ballasting and the RSG can run
at a wide range of  RPMs so there is no timing issues and the spark rate
or Beats Per Minute (BPM) can vary independently from the 60Hz/120Hz
line frequency.

Unfortunately, the diodes in DC supplies can be damaged, which can be
an expense to replace.

Other than that, the basic schematic for the TC  ... primary,  tank
capacitor, spark gap, secondary and top terminal ... all the key
design parts are the same.

DC coils can use a wider range of tank capacitor value, but this is
also related to the primary inductances available.

Assuming it is tuned, an AC coil can run off DC with little or no
design and only minor performance changes if you are willing
to put up with the fixed-frequency RSG.  The ballasting and
safety gaps don't hurt anything.  Brian Basura has done this
successfully on his AC coil.

I suspect that the losses due to the rectifier and limiter resistor
probably do drop the performance since the source impedance
is higher than a well-tuned AC system, but the elimination of the
timing issues may actually compensate enough to balance things
out.

For very high power TCs, the vote is about 50/50 for AC and DC,
although the advantages of DC with three-phase mains seems
pretty important.

The archives for this list have a few posts about AC VS DC coils
and performance and comparisons, all worth looking at.

AC coils are more traditional "pure" Nikola Tesla, but like
salt-water capacitors there are many successful, preferable
and interesting alternatives.

Best,
    Kevin

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, January 19, 2002 8:24 AM
Subject: Do TCs need AC or DC?


> Original poster: "Neil Richardson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <neil-at-opticalrealities-dot-com>
>
> This probably sounds like a stupid question, but I am just curious, so go
> easy on me :-)
>
> Do TCs need AC or DC?
>
>
>