RE: New Primary Design 2
Below is an excerpt from the IEEE tesla document located on the tesla ring
and authored by R M Craven.
"Techniques are now employed whereby two Archimedean spiral primaries are
stacked one on top of another. The mutual inductance M that exists between
them is adjusted by varying the separation of the two coils. This removes
the need for relatively lossy "tapping" connections and also minimizes the
length of conductor needed to make up a given inductance. Thus the I2R or
Joule losses are minimized. A further advantage is that there are no unused
turns and this means that the coupling coefficient remains largely constant
(less change in primary geometry) and there is no extra field stressing
which would occur due to autotransformer action in the primary."
Has anyone on the list used this method? Is it effective? How much available
separation would you have to have to allow for tuning and how would moving
the upper coil up and down effect coupling.
Michael Doyle - Lab Technician
Cherry Electrical Products
11200 88th Ave, P.O. Box 581913
Pleasant Prairie, WI 53158-0913
Phone: (414) 942-6627
Fax: (414) 942-6334
EMAIL: mdoyle-at-cherrycorp-dot-com <mdoyle-at-cherrycorp-dot-com>
From: Tesla List [SMTP:tesla-at-pupman-dot-com]
Sent: Tuesday, September 14, 1999 9:13 PM
Subject: Re: New Primary Design
Original Poster: Gavin Hubbard <ghub005-at-xtra.co.nz
Hello Nick and list
I use a double stacked primary just like this on my 5kVA, 200mm
coil! I use 20mm for the acrylic. In NZ, 3/8OD copper automotive tubing
comes from the shop (Mitre 10) already wound into this form (with the pipe
ends at the outside of each stack, winding inwards and joining at the inside
of each stack).
I am using this approach because it keeps the primary compact,
primary inductance high, and it looks slightly unusual. I'm still tinkering
with this system, but initial tests look very promising.