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

Multiply top and bottom of 1/jwC by j (This does not change its value) and
you get 1/jwC = minus j/wC.

Back to school with your algebra.

On Wed, 15 Oct 2003 02:03:05 +0000 (UTC), "Reg Edwards"
wrote:

Multiply top and bottom of 1/jwC by j (This does not change its value) and
you get 1/jwC = minus j/wC.

Back to school with your algebra.

His algebra looks perfectly fine to me. But as others have pointed
out, he's left the 2pi out.

"budgie" wrote in message
...
On Wed, 15 Oct 2003 02:03:05 +0000 (UTC), "Reg Edwards"
wrote:

Multiply top and bottom of 1/jwC by j (This does not change its value)
and
you get 1/jwC = minus j/wC.

Back to school with your algebra.

His algebra looks perfectly fine to me. But as others have pointed
out, he's left the 2pi out.

------------------------------------------

Yes. I apologise for my remark about school. I gained the incorrect
impression from the previous replies.

The w in wC stands for omega = 2*Pi*F, the angular frequency.

On Wed, 15 Oct 2003 02:43:27 +0000 (UTC), Reg Edwards, said...

"budgie" wrote in message
...
On Wed, 15 Oct 2003 02:03:05 +0000 (UTC), "Reg Edwards"
wrote:

Multiply top and bottom of 1/jwC by j (This does not change its value)
and
you get 1/jwC = minus j/wC.

Back to school with your algebra.

His algebra looks perfectly fine to me. But as others have pointed
out, he's left the 2pi out.

------------------------------------------

Yes. I apologise for my remark about school. I gained the incorrect
impression from the previous replies.

The w in wC stands for omega = 2*Pi*F, the angular frequency.

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.
swapping w and f is another good one. only works for f/f stuff.

mike

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!!!
--

"Windows [n.], A thirty-two bit extension and GUI shell to a sixteen bit patch
to an eight bit operating system originally coded for a four bit
microprocessor and produced by a two bit company."

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!!!
--

"Windows [n.], A thirty-two bit extension and GUI shell to a sixteen bit patch
to an eight bit operating system originally coded for a four bit
microprocessor and produced by a two bit company."

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.