Inductor question

To: tesla-at-poodle.pupman-dot-com
Subject: Inductor question
From: Richard Quick <richard.quick-at-slug-dot-org>
Date: Sat, 7 Sep 1996 06:32:00 GMT
Quoting  Steve Roys <sroys-at-umabnet.ab.umd.edu>:

> 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? 

Steve;

I am coming up with similar data. I obtained about 50 lbs of
finely shredded iron/steel (tin cans mostly) from our local
recycler. Filling and tamping a 6 inch pvc drain pipe and winding
20 turns of #4 AWG insulated wire does not provide sufficent
inductance to ballast down my pigs. Guestimating leads me to
think that this setup would be OK if I was working with 60-100
turns on the form. There is a lot of vibration when I throw a
load on this, but I wanted to get familiar with the idea before
plunking down $$$ for the wire to wind a custom inductor. The
scrap iron was free for the asking.

I should note the scrap is not tightly packed in the tube, and
all 50 lbs is not in use. By placing a section of steel bar stock
in the top of the tube and driving with a 4 lb. sledge I can pack
a lot tighter, but the PVC form will split.

I am still leaning towards the classic induction coil method of
purchasing a spool of soft iron bailing wire, cutting the wire
into sections, coating them, and tightly binding the cut sections
into a bundled core.

Any additional information by other experimenters would be
appreciated.

Richard Quick


... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12