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Re: Line filter -- where to ground it?
Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
Ground the filter to mains grounds.
The 36" spark length is based on the famous John Freau equation of
sqrt(input watts) * 1.7 and is obtainable. Your coil may go a beyond
this if your losses are less than John's. You will likely end up in
the 25" to 30" range without any changes to the coil. Spark length
with this equation is based on input watts (measured at the input to
the NST). If you have a greater amount of losses than John Freau had,
you will have less power to the sparks and a smaller spark length
(it's that simple). But, it's not always "that simple" to find losses
and reduce them. That is always a challenge.
One very simple example of losses is the NST itself. If John's NST
(used during those measurements) was more efficient than your NST,
you will lose out no matter how well the coil is built. Coilers
always upgrade this gizmo and that gizmo trying to stretch those
sparks, but sometimes still can't attain John's efficiencies. When
that happens, the hv transformer is an obvious reason. But, so what
if John could get 36" and you got 30". No big deal. But, if your
getting only 10", well, then there's a problem.
If you get to a point where you want longer sparks and don't care
about the watts, you can always remove shunts in the NST (a lot of
dirty work, but it's been done many times). If enough shunts are
removed to double the current, you will end up with a 15/60 (900W)
with a spark length of 51" obtainable. If there's one thing I've
learned in this life-sucking hobby, the bond between power and spark
length is very strong, not always linear, but still very strong.
Tesla list wrote:
Original poster: "Forest Darling" <fdarling@xxxxxxxxx>
I am going to wire a line filter behind a neon sign transformer in
backwards, but where should I ground the filter to? The NST case, or
the mains ground?
The NST case is going to be grounded to the RF ground (I'm using a
Terry filter on the high voltage side.)
Also, out of curiosity, how long of a spark would you expect a 450
watt 15kV 30mA NST to realistically be able to put out?
DeepFriedNeon's calculator said 36" but that seems very long.