[Prev][Next][Index][Thread]

Inductor question



I am playing around with a variable inductor that has a 4" diameter
sliding core packed with 20 pounds of welding rods (idea compliments of R.
Hull) that I plan on using to regulate the current in my 50A controller,
and I have a few questions.

I don't really have the right wire to wind it with yet, so I just wound it
with some heavy wire (2 or 4 gauge maybe with fairly thick insulation) 
that I had to see how it works.  There aren't a lot of turns in the 13"
winding length, so the inductance is pretty low, but I noticed that the
difference between the core being totally out of the winding and totally
in is less than a factor of 5.  Is this reasonable for 20 lb of iron
welding rods or could something else be screwed up?  Using Wheeler's
formula for the inductnace of an air-core solenoid, I compute a value
that's pretty close to what I measured with the core out, but I would have
thought that the iron would have made much more of a difference.  Would
winding a coil with 6 gauge magnet wire (which would give me a much higher
inductance to start with) make more of a difference?

Thanks in advance.

Steve Roys.