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Skin effect and aluminum question (fwd)




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From:  Jim Fosse [SMTP:jim.fosse-at-bjt-dot-net]
Sent:  Wednesday, February 18, 1998 1:44 AM
To:  Tesla List
Subject:  Re: Skin effect and aluminum question (fwd)

[snipollas]

Chip asked:

>> I have seen it mentioned on the list that aluminum is a poor choice of 
>> conductor because the oxide layer that forms on the surface is an 
>> insulator, and that if, for example, your oxide layer is 0.001" thick and 
>> your frequency is such that you only have current going through the top 
>> 0.006" of the conductor, you will then lose 1/6 of your available conductor.
>> 
>> Can anyone convince me that I'm wrong?  I am aware that the aluminum 
>> conductor may provide more resistance at connections because the 
>> electricity has to penetrate the oxide layer though.

>Sometimes I think that certain things are repeated so many times that
>they eventually take on the ring of authority without, however, having
>a solid basis in fact. At other times a material or technique may be
>rightly labelled as below par, but for the wrong reasons.
>

Every one has missed the fact the we've been building our "home
rolled" caps with Al sheet or foil for years. (well 3 years in my
case) That Al was oxidized before I even bolted on the connecting
wires.

Commercial caps use Al foil for their electrodes but have had the
connections spot or pressure welded on. (I'm ignoring silver-micas
, semiconducting and tantalums for now;) Has anyone blown up a
commercial pulse cap and found copper foil inside? Ed, Bert ...?

Try this: place 2 pieces of Al wire in series with the primary circuit
of your TC. Just have the 2 pieces of wire laying atop each other. Now
turn on the power. What happened? Did your TC work well? Did it catch
fire?

My guess - it ran well and may have even spot welded the 2 pieces of
wire together. I'll try it tomorrow with my new coil.

	cheers,

	jim