[Amps] resonance

[Jim Forsyth]

Needs more refinement! In a parallel tuned circuit containing resistance, Xl 
and Xc are not equal at the resonant frequency.


----- Original Message ----- 
From: "Bill Fuqua" <wlfuqu00 at uky.edu>
To: "Amps" <amps at contesting.com>
Sent: Monday, June 05, 2006 6:51 AM
Subject: [Amps] resonance


> Maybe it is time to change the thread.
>   Passive Resonance is a frequency selective means of storing oscillating
> energy. It occurs when energy oscillates back and forth between two
> complementary energy storage mechanisms. In the case of the pendulum you
> have kinetic and potential energy.   In a circuit the storage mechanisms
> are the inductance and capacitance. The inductance is the kinetic energy
> storage mechanism  and  the capacitance is the potential storage
> mechanism.  When there is a balance between these  Xc=Xl the circuit is at
> resonance. That is because all the energy from one goes to the other and
> back except for the bit that is lost in the resistance. A pure resistance
> alone is not resonant. That is the flaw in defining resonance as when 
> Xc=Xl
> alone.  In a resistor zero does equal zero at all frequencies.
>    Another property of resonance is that besides selectivity the energy
> stored in the system is greater than that passing to or from it when at
> equilibrium. And the Q is the amount of energy stored divided by the 
> amount
> of energy going into the resonant system during each cycle. We usually see
> the other definitions regarding  reactance and resistance and bandwidth 
> and
> resonant frequency. All three produce the same unit-less value.
>    I use the term passive because some of the properties of passive
> resonance (not all) can be accomplished by active filters and by digital
> methods.  Even though a "flywheel" may store oscillating energy it is not
> frequency selective, thus not resonant. We often use the term "Flywheel
> Effect" but "Pendulum Effect" may be more accurate.
>
> 73
> Bill wa4lav
>
>
> At 10:45 PM 6/4/2006 -0400, Bill Coleman wrote:
>
>>On Jun 4, 2006, at 8:23 AM, R L Measures wrote:
>>
>> > My dummy load is non-resonant, so that's a problem?
>>
>>Dummy loads are resonant by definition, since they provide a purely
>>resistive impedance. (ie X = 0 is the definition of resonance)
>>
>>
>>
>>Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
>>Quote: "Not within a thousand years will man ever fly!"
>>              -- Wilbur Wright, 1901
>>
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>
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