Re: OLTC - Split core inductors

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
> 
> Hi Ed and Jim,
> > I think Jim was referring to inductors made of wide copper ribbon but with
> no metal core, just air.  If anyone has a link or info on these, I can
> check into this.  I may be a solution if the copper/kapton does not get too
> expensive.  Simple to make and low resistance for sure!  They use these at
> work for some things but I know little about the theory or design equations
> behind them.  The spec would be:
> 
> 150mH
> 5 amps peak
> ~1 ohm or less of resistance.
> 
> The copper could probably be very thin.  DigiKey sells 0.75 inch kapton but
> other tapes would work too in this less than human space flight
application ;-)
> 
> MSC has two inch wide, 0.005 inch copper ribbon for $52/100 feet.  2-inch
> platting tape could be used I bet (tough, thin and cheaper than kapton).

	Maybe you're right!  I overlooked the "air"!  But, if so, I've never
heard of them and would also be curious.  For the record, many
high-power traveling-wave amplifiers use a focussing solenoid wound with
aluminum foil and insulated only with the oxide film on the aluminum. 
At least that's what I was told by an engineer at the old Hughes
Electron Devices Division.  I have no idea as to how to calculate the
inductance, but perhaps Paul or someone else on the list can work it
out.

Ed