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Re: Inductor question



On Sat, 7 Sep 1996, Tesla List wrote:

> For short term use (~1minute) you do not need such large wire. The
> 500mA or 700mA per square mil wire sizing equation is for transformers
> that operate day in and day out with only an 50 degree C temperature
> rise (50 degrees C: memory here) I would guess that I get a 50 degree
> C rise above ambient in 1 minute. For longer run times or higher
> currents use larger wire. 2-4 gauge is a bit large;) 19 gauge is to
> small! How about 12 gauge?

The 2-4 gauge was just for kicks because I had it laying around.  I knew
that it wouldn't give me the inductance that I needed, but I just wanted
to get some idea of how my "variable" core would work.

> I am going to ask, what seems to be an obvious question here, with no
> slight intended. Are the welding rods that you used mild steel?
> Stainless? Bronze;) I started doubting myself and checked my Bronze
> brazing rods with a nydodium(sp) magnet. Not magnetic;) phew! I still
> remember that info;)

I'm not exactly sure about whether they're the mild-steel or just
plain iron, but they are definately magnetic, and the box says that the
coating also contains powdered iron.

> How did you determine the inductance of your solenoid? LCR bridge?
> Current based calculation? Based on my results tonight, I'll have to
> double and triple check all my measurements using my Leader LCR
> bridge.

I used a digital LCR meter.  As soon as I excavate my workbench, I'll
double check it with my GR bridge, but I'm pretty sure the values I got
were correct.

Steve Roys.