Re: OLTC-Inductors

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Terry,
          I began to try an idea a few years ago which you might be 
able to use:

On 15 Aug 2002, at 23:32, Tesla list wrote:

> Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
> 
> Hi All,
> 
> Well, I guess I should have known I was in trouble when I got zero response
> to this one :-))  
> 
> I dumpster dived for some inductor cores today and found and made up this
> fancy 75mH choke:
> 
> http://hot-streamer-dot-com/temp/OLTC8150011.jpg
> 
> but it saturated in testing:
> 
> http://hot-streamer-dot-com/temp/OLTC8-15-02.gif
> 
> Oh oh..  That amps per turn stuff...  I ain't no golly darn transformer
> design genius...
> 
> I played with some transformers and such but saturation is a BIG issue!  I
> took an old core from a variac and sliced it with a little finger nail
> file...  Hahaha!!  I used a cobalt alloy M42 hacksaw for cutting mil grade
> 6-4 titanium :o))  Cut it like butter...
> 
> http://hot-streamer-dot-com/temp/OLTC8150009.jpg
> 
> It solved the saturation and gave ideal inductor responses:
> 
> http://hot-streamer-dot-com/temp/OLTC8-15-01.gif
> 
> But it only measured 47mH....
> 
> So, to make a long day's story short, the resonant charging inductor is a
> big issue!!...  I think it has to work at 120Hz (helps a LOT! as opposed to
> 60Hz...)  Saturation is a killer.  Probably going to need some "big iron"
> cores here!  Not to bad really, but I thought this would be a trivial
> part...  I don't think an air core inductor would work given the low (5
> ohms) resistance needed.
> 
> The Devil is in the details...
> 
> Cheers,
> 
> 	Terry

I grabbed throw-out SMPS from anywhere I could get them, pulled all 
the *transformers* (NOT chokes) out, and smashed the cores up, 
finally stuffing the broken pieces into a PVC pipe. The material is 
N27/3C8 mostly and would work well up to 100kHz. It would make an 
ideal core for a high frequency choke. Adjustable too.

Regards,
malcolm
<snip>