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Re: [TCML] Why air-core?



I have used a small car ignition coil, driven by a full H-Bridge at a resonant frequency of around 20kHz (at approximately 60Vpp) to produce a mini plasma speaker. The output voltage is well over 30kV before breakdown of the spark gap occurs. Pushing it to higher voltages causes breakdown of the plastic casing, a phenomena it survived for well over a half an hour before I noticed the small purple streamers pouring out the bottom and onto my bench.
 
TV flyback transformers can also be operated as resonant rise systems to produce high voltages.
 
So non air core systems are definately around but I have no knowledge of a system that operates in the hundreds of kilovolts range that is not air-cored. 
 
David
 
 
> On 10/1/2011 7:16 PM, Gary Lau wrote:
>> I was asked a fundamental question about Tesla coils recently.  I
>> _think_ I
>> knew the answer, but I'd like to check.
>>
>> A Tesla coils is strictly an air-core transformer.  I said that steel
>> or
>> ferrite cores are not used because:
>> 1) Core saturation would be likely
>> 2) The conductive core would degrade the high voltage standoff
>> capability
>> 3) The coupling with a cored design would be too high
>>
>> Did I get it right?
>>
>> Thanks, Gary Lau
>> MA, USA
>> _______________________________________________
>> Tesla mailing list
>> Tesla@xxxxxxxxxx
>> http://www.pupman.com/mailman/listinfo/tesla
> I strongly agree with 1, core saturation would defiantly be a problem,
> particularly with a DRSSTC. At hundreds of amps peak you would need an air
> gap so big you may as well call it air core... This is how I figure it.
>
> Another thing I may add to that list  is that the size of the core would
> likely be massive if you could manage to get it to not saturate. A core of
> this size would be very unwieldy and heavy.
>
> 2 and 3 almost make logical sense to me.
>
> Eric
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
>


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