R + jwL + 1/(jwC)
= R + jwL -j/(wC)
so at resonance wL=1/(wC)
ie w=1/sqrt(LC)

Chris

"Michael" wrote in message
om...
The impedance should be R + jwL + 1/(jwC)


You sure?, how do the j parts cancel at resonance if they are both added?+

On 14 Oct 2003 17:51:11 -0700, (Tom Bruhns) wrote:

Which voltage and which current? Clearly the voltage across the
capacitor will always be pi/2 relative to the current in that
capacitor, and the same (but opposite sign) for an inductor. Also,
are you doing an AC or a transient analysis? If transient, are the
transients settled, are you really on the resonance frequency, and are
you simulating with sufficient time resolution? Oh, and I'm not quite
sure what you mean by "lambda/4" phase shift. Is that degrees or
radians, and what's lambda?

---
Since he calculated the resonant frequency of the circuit using

f = 1/sqrt(L*C),

his answer will always be a frequency 6.28 times higher than it should
be, so the reactance of the inductor will be greater than the reactance
of the capacitor, making the phase angle positive.

"Lambda" is usually taken to mean wavelength, so "lambda/4" would mean a
quarter wavelength; in this context, 90°, the approximate phase
difference between his simulated voltage and current.

--
John Fields

On 14 Oct 2003 17:51:11 -0700, (Tom Bruhns) wrote:

Which voltage and which current? Clearly the voltage across the
capacitor will always be pi/2 relative to the current in that
capacitor, and the same (but opposite sign) for an inductor. Also,
are you doing an AC or a transient analysis? If transient, are the
transients settled, are you really on the resonance frequency, and are
you simulating with sufficient time resolution? Oh, and I'm not quite
sure what you mean by "lambda/4" phase shift. Is that degrees or
radians, and what's lambda?

---
Since he calculated the resonant frequency of the circuit using

f = 1/sqrt(L*C),

his answer will always be a frequency 6.28 times higher than it should
be, so the reactance of the inductor will be greater than the reactance
of the capacitor, making the phase angle positive.

"Lambda" is usually taken to mean wavelength, so "lambda/4" would mean a
quarter wavelength; in this context, 90°, the approximate phase
difference between his simulated voltage and current.

--
John Fields

On Wed, 15 Oct 2003 09:18:51 +0100, Paul Burridge, said...
On Wed, 15 Oct 2003 06:11:13 GMT, Active8
wrote:

now that were all done playing with j...

don't forget

Z = sqrt{R^2 + [(wL) - (1/wC)]^2]}

and

Z(s) = R + Ls + 1/Cs

which is just plain easier to deal with 'til you need to journey back
into time domain land. no need to leave it f(t) for this deal, though.

all that j stuff... that was scary ****. so easy to make a mistake.

Especially so given the limited typography of this particular medium.
I suspect few of us would have a problem if we could only view these
formulae in a suitably appropriate typeface!!!

what pre tell, is a typeface that would make it hard? wing-dings?

i admit, even in HTML with arial or fixed-pitch, where you have sub and
super tags and greek letter codes, you can't do much. i tried a few free
math notation tools for HTML and wasn't happy. plus you need a plugin
for most if not all. W^3C has a standard. i'd like to see more math
capabiliies in browsers. we could attach formulae without violating the
no bianaries rule. of course microshaft and standards will probably
never be seen in the same line of code.

i still don't see why text based math legibility is font dependant. i
see i could have eliminated some clarifying parens by

- -
| 2 1 2 |
sqrt | R + ----- | or a 1/2 power instead of sqrt
| jwC |
- -
created by Andy´s ASCII-Circuit v1.22.310103 Beta www.tech-chat.de

does that also foul up?

brs,
mike

On Wed, 15 Oct 2003 09:18:51 +0100, Paul Burridge, said...
On Wed, 15 Oct 2003 06:11:13 GMT, Active8
wrote:

now that were all done playing with j...

don't forget

Z = sqrt{R^2 + [(wL) - (1/wC)]^2]}

and

Z(s) = R + Ls + 1/Cs

which is just plain easier to deal with 'til you need to journey back
into time domain land. no need to leave it f(t) for this deal, though.

all that j stuff... that was scary ****. so easy to make a mistake.

Especially so given the limited typography of this particular medium.
I suspect few of us would have a problem if we could only view these
formulae in a suitably appropriate typeface!!!

what pre tell, is a typeface that would make it hard? wing-dings?

i admit, even in HTML with arial or fixed-pitch, where you have sub and
super tags and greek letter codes, you can't do much. i tried a few free
math notation tools for HTML and wasn't happy. plus you need a plugin
for most if not all. W^3C has a standard. i'd like to see more math
capabiliies in browsers. we could attach formulae without violating the
no bianaries rule. of course microshaft and standards will probably
never be seen in the same line of code.

i still don't see why text based math legibility is font dependant. i
see i could have eliminated some clarifying parens by

- -
| 2 1 2 |
sqrt | R + ----- | or a 1/2 power instead of sqrt
| jwC |
- -
created by Andy´s ASCII-Circuit v1.22.310103 Beta www.tech-chat.de

does that also foul up?

brs,
mike

....snip

i still don't see why text based math legibility is font dependant. i
see i could have eliminated some clarifying parens by

- -
| 2 1 2 |
sqrt | R + ----- | or a 1/2 power instead of sqrt
| jwC |
- -
created by Andy´s ASCII-Circuit v1.22.310103 Beta www.tech-chat.de

does that also foul up?

brs,
mike



Oh, Mike. That's ugly!! Strangely, when I see it in this window I type
replies in, it's much clearer! Hey, ho. I agree with you about viewing
these things in browsers... always hard. For my money, the first ones in
this chain were as good as any I've seen

....snip

i still don't see why text based math legibility is font dependant. i
see i could have eliminated some clarifying parens by

- -
| 2 1 2 |
sqrt | R + ----- | or a 1/2 power instead of sqrt
| jwC |
- -
created by Andy´s ASCII-Circuit v1.22.310103 Beta www.tech-chat.de

does that also foul up?

brs,
mike



Oh, Mike. That's ugly!! Strangely, when I see it in this window I type
replies in, it's much clearer! Hey, ho. I agree with you about viewing
these things in browsers... always hard. For my money, the first ones in
this chain were as good as any I've seen

all that j stuff... that was scary ****. so easy to make a mistake.
swapping w and f is another good one. only works for f/f stuff.

mike

I get a bit scared of all the j's too, I prefer polar. Usually you
want a magnitude and angle in the end result anyway.

all that j stuff... that was scary ****. so easy to make a mistake.
swapping w and f is another good one. only works for f/f stuff.

mike

I get a bit scared of all the j's too, I prefer polar. Usually you
want a magnitude and angle in the end result anyway.