L for inductor?What's with the page of math on the impedance calculations for parallel resonant circuits?
Why not just use the old (apparently, lost knowledge?) formula of Z = 2*pi*f*L*Q?
What in the world are you looking at? f you have some specific criticism of some web page then A) reference that page and 2) state your issue.The Sound of Music said:"When you know the notes to sing...
you can sing most anything!"
Because calculating this way is not as simple as this, or more people would do it that way.Why not just use the old (apparently, lost knowledge?) formula of Z = 2*pi*f*L*Q?
They would do it if they knew about it.Because calculating this way is not as simple as this, or more people would do it that way.
You are quoting a formula for an isolated stage.
1. The issue: I was hoping to find a simple formula somewhere on the web for calculating or even approximating the impedance of a parallel resonant circuit with internal series resistance of the inductor. I didn't want to have to go brush up on j operators or complex numbers to arrive at a figure for ohms.What in the world are you looking at? f you have some specific criticism of some web page then A) reference that page and 2) state your issue.
Ragwire - are you sure about this equation? Did you proof or justify it ?Why not just use the old (apparently, lost knowledge?) formula of Z = 2*pi*f*L*Q?
I think this gets to the nub of the OP's question. People use math differently. For instance if I needed to calculate the volume of a cone, I would have little interest in finding "the formula" for that in some book. I would do the triple integral and prove the formula. Only then might I take a look to make sure the two approaches agree. To me, a formula presented without proof is next to useless.Ragwire - are you sure about this equation? Did you proof or justify it ?
It is not mine. It is from a publication by John F. Rider. I am pretty sure this is the way I learned it in school--and had forgotten.Ragwire - are you sure about this equation? Did you proof or justify it ?
For my opinion, the quality factor Q is a fixed quantity, right?
Does this mean that the impedance Z is increasing continuously with frequency f?
Or did I misinterprete anything?
True indeed. It may be difficult for those who do mathematics for mathematics' own sake to understand that 99% of us just want a result, and quickly, so we can get back to whatever we are trying to accomplish. I have no interest in re-inventing the wheel. I am just disappointed that it is so difficult in this day and age to find practical information that I worry what will happen when the last of the vintage books rots away.I think this gets to the nub of the OP's question. People use math differently. For instance if I needed to calculate the volume of a cone, I would have little interest in finding "the formula" for that in some book. I would do the triple integral and prove the formula. Only then might I take a look to make sure the two approaches agree. To me, a formula presented without proof is next to useless.
But not everyone sees it this way and many just want "the answer". Different sources are written for different users.
I agree. I think it saves steps.The use of Q is quite interesting.
And herein lies the problem. You were taught to be an equation monkey. You were fed equations and told when and how to use them. You don't understand where they come from or why they are valid in some circumstances and not in others. Hence, when you forget them, you have no fundamentals to fall back on and figure it out, you have to go hunting around for someone to feed you the equations all over again.It is not mine. It is from a publication by John F. Rider. I am pretty sure this is the way I learned it in school--and had forgotten.
by Jake Hertz
by Jake Hertz
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by Jake Hertz