Re: [TCML] Racing sparks - question

[Joe Mastroianni <joe@xxxxxxxxxxxxxx>]

HI Bert,

I can't thank you enough for the detailed explanation.   

After I wrote the note to you I went back to a couple books - and I think your explanation as a modulation makes the most sense to me.  Heterodyne  2 signals, get sum and difference as well as the two original ones.  If the k is high you get this sum/difference generation, low k, the detuned primary can happily coexist at it's own freq - not that the sum and differences aren't happening, they're just very suppressed.

Makes sense, absolutely.

Your explanation is actually one of the clearest I have read.  Worth saving and rereading.

Thanks so much,
Joe


On Aug 9, 2010, at 8:23 PM, Bert Hickman wrote:

> Joe Mastroianni wrote:
>> Hi Bert, Thanks - I think I understand (I hope).   When you over
>> couple the frequency response of the system exhibits a double-pole,
>> and so you have two frequency components, one in the primary and a
>> different one in the secondary, and they're going to exhibit
>> "beating" phenomena.  That's the mental picture I have now - tell me
>> if I'm wrong.
> 
> This is always confusing to new coilers. Coupled tuned circuits are deceptively complex, especially since, with most Tesla coils, we're dealing with their transient response. Unfortunately, most textbooks tend to deal only with (simpler) steady-state response. In fact, the general case for lossy coupled resonant circuits was only recently correctly solved by a TCML list member (Antonio Carlos M. de Queiroz). Earlier closed-form solutions either were for the lossless case, or had previously undiscovered errors in the formulae.
> 
> Unfortunately, the mental picture you have is not quite right. Even if the primary and secondary circuits are initially tuned to exactly the same resonant frequency (when the systems are isolated from one another), coupling the circuits introduces a complex, multi-cycle energy transfer process whereby the "bang" energy cycles from one LC circuit to the other then back again. Although each energy transfer may take several cycles, the process can be quite efficient at transferring most of the initial energy from one circuit to the other.
> 
> One way to view it is that the "amplitude" of the oscillations in each circuit are being "modulated" as energy transfers from one LC circuit to the other. In fact, it is the change in amplitudes that cause the lower and upper frequency "humps" to appear. This is analogous to the frequency spectrum for AM radio, where audio modulation creates upper and lower sidebands on each side of the carrier frequency.

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