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Something For Nothing




From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: 	Wednesday, October 29, 1997 12:40 AM
To: 	tesla-at-pupman-dot-com
Subject: 	Something For Nothing

Yes Folks! You read it here.
                             I have finally done a definitive test of 
a stacked spiral primary and it works extremely well. The something 
for nothing bit is that if you built the bundle of copper tube I 
bought into a single flat spiral you might scratch 50uH from it. 
Arranging it in two layers with a sheet of acrylic in between brought 
it close to 80uH simply by making use of mutual inductance. The 
tubing is 3/8". It came as a 2- layer coil that spiralled in on one 
layer then back out again on the next. If you lifted the outer turn on 
one side it would form what looked like an hour-glass.
     To make the coil I cut a circular hole in the acrylic and 
"threaded" the tube onto it, then finally held the turns on each side 
with hot-melt. Looks great and works great :)
     I would like to stress that this is not a world first as others
have thought of it before and similar schemes can be seen in the 
transmitter rooms of old times.

Malcolm