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Re: Ferrite chokes & saturation - why toroids?




From: 	Adam[SMTP:absmith-at-tiac-dot-net]
Sent: 	Tuesday, November 25, 1997 10:02 AM
To: 	Tesla List
Subject: 	Re: Ferrite chokes & saturation - why toroids?


>> The "U" core shape definitely seems easier to wind- is iron power 
>> available in shapes other than toroid? 
>
>Rods and slugs AFAIK.
>
>> Is there a good reason for using the toroid?
>
>Not for this application to my knowledge (other than to minimize 
>radiation). But I've used ferrite rods in chokes with no real 
>problems. Perhaps someone who chose that core shape could answer this.
>
>Malcolm

I guess the toroid is so popular then because it is a common type of 
closed-core form (flux contained) that is readily available.   Rods and 
slugs are great for making chokes for many applications, but I suspect 
that if these open ended core forms get too close to the Tesla primary, 
you could be in for some seriously unwanted induction- esp. if the cores 
are lined up axially with the tesla coil!  For those of use whose power 
supplies are housed just below the coil itself, closed core chokes are a 
must.  This is what led me to the double "U" cores from my flyback 
xfrmrs, though I suspect mine saturate at my current power levels.

That leads me to another question- If I cannot find larger "U" core forms 
than the flyback material (which I have in abundance) to build higher 
current chokes, can I simply wind four (or more) identical chokes and put 
them in series-parallel to increase power handling while maintaining the 
value (10 mH)? This seems like a valid approach, and should also better 
distribute the voltage across the chokes in series.

-Adam

 

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