Since the discussion came up about dummyloads, and I remembered about
how non-inductive resistors were wound, I couldn't think of the winding
type name in the last post. The type of winding used is the
"Ayrton-Perry" winding. It takes two lengths of nichrome wire which
seriesd will equal 50 ohms or 25 ohms each. They are wound bifilar on a
form. On one end, they are connected together and the other end has the
two leads. This throws the two windings 180 degrees out of phase and
cancels the inductance. This would be the same as hooking up two
transformer windings out of phase and killing the inductance. This is
exactly what is needed in the case of a non-inductive resistor. The
windings would need to be spaced so they didn't contact each other along
the length. The Alloy 87 I read about with 7/8 ohms per foot would be
somewhat ideal for this. Something like two lengths 28-1/2 feet would
equal 25 ohms each. It don't take much to wind up 28-1/2 feet of wire
around a form. Every 3.8 turns around a 1" diameter form is 1 foot.
Thats only 108-1/2 turns which don't take up too much space. I wouldn't
see any problem experimenting with this is that alloy wire is affordable
and large enough to do whats wanted.
Will Matney
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