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RE: Series or Parallel resonant ? ( was: New pics and scope waveforms)

Hi Malcom,
Thanks for your response.
Please see my earlier reply to Richie's feedback.

I disagree with your response:
>The truth is that both 
>types exhibit a current maximum and a voltage maximum across 
>their individual components at resonance. 

I believe the essence of whether LC parallel components
 are series or parallel resonant depends upon where 
 the source generator is in the circuit.

Series resonance: generator is part of the series LCR.
All Rdc's are in series.

Parallel resonance: generator is across "Both" L and C physically parallel.
  The generator sees L's resistance different than in the series model
  in that C is across the generator, L+RdcL is across the generator.

In this context, I stand by my original statements.

I agree this is all very confusing, I hoped to make it clear (?) sorry.

There appears to be easy confusion stemming from components in parallel
contrasted to how they are driven,
  generator in series with parallel components (Igen=max) or
  a generator driving across parallel components (Igen=min).

In your radio set front end example
 assuming parallel resonance,
 the incoming signal (a generator) appears across both L & C at same time,
 the voltage must be minimum else the current couldn't be minimum
 to represent minimum load to the incoming signal at Fo.

I agree with 
>the secondary is more driven at Fr than by an impulse,
sorry if I was misleading....

even the Primary simply and highly selectively at Fr extracts the
fundamental
 of the square impulse provided by a spark gap switch.
 Current injected by the gap switch is accepted by the Pri LC sinusoidally,
 not as rectangular impulse, due to the frequency selectivity of the LC
 and that rectangular waves are composed of sinewaves which LC is able to
isolate.
 The LC actually highly rejects all energy outside the fundamental resonant
freq.
 High order harmonics see a very high impedance producing little current
 due to their divergence from the highly selective resonant frequency. 

Experiment: set up a lowZ (simulating Rgap) square wave generator driving
 a HI-Q toroid inductor and mica cap in series resonance.
 The fundamental sinewave provides most of energy at resonance benefiting
from 
 Vpk_fund = 4/Pi*Vpk_squarewave peak {flat top] amplitude !

 Placing a high value load resistor across LC demonstrates
  affects of De-Q'ing, equivalent series resistance, etc.
  simulating Spark loading,  without sparking !

Regards,
Dale

-----Original Message-----
From: Tesla List [mailto:tesla-at-pupman-dot-com]
Sent: Wednesday, December 15, 1999 5:13 PM
To: tesla-at-pupman-dot-com
Subject: RE: New pics and scope waveforms

Original Poster: "Malcolm Watts" <malcolm.watts-at-wnp.ac.nz> 
> Original Poster: Dale Hall <Dale.Hall-at-trw-dot-com> 
> 
> Richie,
> Verrry nice presentation. Great work. Thanks for the effort.
> 
> One befuddlement:
> The Secondary is referred to as being parallel resonant.
> At parallel resonance, voltage is minimum across LC 
>   and minimum current is sourced from a parallel generator.

Voltage is minimum across a parallel tuned circuit at resonance?? 
The front end of most radio sets includes such a circuit to present a 
minimum load to the incoming signal at Fo isn't it?
 
> In a classic TC, Primary energy and its loss resistance
>   is coupled as a low impedance series generator into the Secondary,
>   effecting a Series Resonant condition.
>   The generator current is maximum (requiring a low Z source),
>    limited by Rdc_inductor+SeriesEquivCoupledPri&ArcLoad,
>    the LC junction (top of Sec) voltage is maximum at resonance.

One might also see the secondary as a parallel circuit (an inductor 
in parallel with its distributed capacitance) mightn't one?  How does 
one classify the primary - series or parallel?  The truth is that both 
types exhibit a current maximum and a voltage maximum across 
their individual components at resonance. 

>    Discharges represent resistance in parallel with both Sec L & C,
>    that can be represented as an equivalent Sec series resistance.
> 
> Comment ?  

Agree with the last statement.

> Am I confused ? perhaps series=parallel depending on how viewed ?
> 
> The Primary LC is parallel resonance since energy is provided
>   in parallel from precharged Pri Cap prior to a brief switch closure
>   to transfer stored energy.
>   When the switch is open the generator charges the Cap in 
>   a dormant, not part of the resonant period, isolating its losses (?).
> 
> Perhaps the confusion is due to the impulse excitation of TC's Vs
continuous
>  nature of the generator (signal source) so a comparison loses meaning ?

Actually, the secondary is more driven at Fr than by an impulse, 
albeit a decrementing wavetrain by virtue of losses and finite circuit 
energy from the primary cap.

Regards,
Malcolm 
<snip>