RE: H/D ratio

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Luke" <Bluu-at-cox-dot-net> 

Ok now we got the juices flowing.
I didn't know the exact formula for max inductance thanx.

Now as for a height of only 9" and a dia of 20" just a common sense look
at it will tell you it may not work.  And judging from the other coils
out there only reinforces those thoughts.

So a taller coil would need to be made.  So how much taller and why?
Why would you start with a 20" dia or any dia at all?

thanx

Luke Galyan
Bluu-at-cox-dot-net

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Thursday, January 15, 2004 10:34 AM
To: tesla-at-pupman-dot-com
Subject: Re: H/D ratio

Original poster: Mddeming-at-aol-dot-com

In a message dated 1/15/04 10:34:31 AM Eastern Standard Time,
tesla-at-pupman-dot-com writes:
Original poster: "Luke" <Bluu-at-cox-dot-net>

I found on the net in a few places stating that the maximum amount of
inductance from a coil is when the height is the same as the
diameter.  This is a 1:1 ratio.

If that is the best inductance ratio then why is this ratio not used for
the Tesla coil secondary to take advantage of a high inductance ratio
between the primary and secondary?

Luke Galyan
Bluu-at-cox-dot-net

Hi Luke,
      Don't confuse "maximum inductance" with "best size". Actually, in a

solenoid coil, the maximum inductance for a given length and diameter of

wire occurs at h=0.9r. IIRC a paper on maximizing inductance was posted
to
the list in April 2002. In such a design, a 20-inch diameter coil would
be
only 9 inches high! The voltage gradient along the coil would be
extreme,
(~50 kV/in), and a toroid sitting only a foot or so above the primary of

such a coil would preclude the possibility of any arcs except to the
primary.  Such low ratio coils might have some application in magnifier
designs, but for a standard TC it's just not practical. Like life, a
Tesla
Coil is a balance between many conflicting desires.

Matt D.