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Re: Tesla Coil RF Transmitter

Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 11:17 PM 9/26/2005, you wrote: 
Original poster: Ed Phillips <evp@xxxxxxxxxxx>

"Excellent point, and a good example of a frequency selective system
that's band limited.
Hmm, though, can one create an arbitrarily sharp cutoff with only
RC?  I think not, off the top of my head."

        We used to have a guy at Hughes named Lou Weinberg who had the
reputation of being a real expert on network synthesis.  I heard him say
that, using only PASSIVE RC circuits, it was possible to synthesize any
transfer function shape if the loss were allowed to be arbitrarily
large.  Don't know if it's true or not.  Certainly with a little
feedback you can get arbitrarily sharp response.

Ed

I've thought a bit (and am too lazy to go find my copy of Mason and Zimmerman, which I'm sure would have the answer)..

I think you're right. I was having trouble figuring out how to get sharp nulls (or more properly, sharp cutoffs). A series of RC networks can get you more than 180 degrees of phase shift, and if you sum the 180 and the 0 path appropriately, you get a null. One can always string up multiple nulls (at different frequencies) to get what you need.

I don't know that you can get the classic resonance curve, though (except with a huge number of sections).