Resonance Frequency of a parallel RC/RL circuit - Expression.png (1/1)
 

Resonance Frequency of a parallel RC/RL circuit - Expression.png (1/1)
 

On Sat, 16 Oct 2010 14:53:39 -0700, wrote:

Excessive obtuseness....

Ga-a-a-a-a-ack!

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I can see November from my house :-)

Resonance Frequency of a parallel RC/RL circuit - Expression.png (1/1)
 

Jim Thompson wrote:
On Sat, 16 Oct 2010 14:53:39 -0700, wrote:

Excessive obtuseness....

Ga-a-a-a-a-ack!


Sorry, I thought "resonant frequency: was 1/(2*pi*SQRT(L*C))

Thanks,
Rich

Resonance Frequency of a parallel RC/RL circuit - Expression.png (1/1)
 

"Rich Grise" wrote in message
...
Sorry, I thought "resonant frequency: was 1/(2*pi*SQRT(L*C))

For an LC circuit, yes. For a damped RLC (series or parallel), there's an
L/R or RC time constant which reduces it. This is called the
pseudofrequency.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

Resonance Frequency of a parallel RC/RL circuit - Expression.png (1/1)
 

"Fred Abse" wrote in message
d...
On Sun, 17 Oct 2010 16:54:53 -0500, Tim Williams wrote:

For an LC circuit, yes. For a damped RLC (series or parallel), there's
an
L/R or RC time constant which reduces it. This is called the
pseudofrequency.

Only in the parallel case.


I went 100 deep with Google looking for a "Resonant frequency Calculator"
that
allows individual -capacitor loss resistance- and -inductor loss
resistance-, or Q
of the individual cap and inductor. Didn't have any luck.
Anyone know of an online calculator that puts all of phantom at aol's
formula
behind a few for inputs and buttons.
MikeK.




--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)

Resonance Frequency of a parallel RC/RL circuit - Expression.png (1/1)
 

amdx wrote:
"Fred Abse" wrote in message
d...
On Sun, 17 Oct 2010 16:54:53 -0500, Tim Williams wrote:

For an LC circuit, yes. For a damped RLC (series or parallel),
there's an
L/R or RC time constant which reduces it. This is called the
pseudofrequency.

Only in the parallel case.


I went 100 deep with Google looking for a "Resonant frequency
Calculator" that
allows individual -capacitor loss resistance- and -inductor loss
resistance-, or Q
of the individual cap and inductor. Didn't have any luck.
Anyone know of an online calculator that puts all of phantom at
aol's formula
behind a few for inputs and buttons.
MikeK.


You might look at the QL_QC program from G4FGQ archive site at
http://www.zerobeat.net/G4FGQ/page3.html. It starts with entry of the
Inductance , Inductor Q, Capacitance, Capacitor Q, test freq, and calculates
a bunch of stuff from those data.
The calculated data returned a
resonant freq
magnitude of impedance ---
angle of impedance |
equiv shunt resistance |
equiv shunt j(x) | at test freq
equiv series resistance |
equiv series j(x) ---
reactance of L and C at resonant freq
coil series loss resistance
capacitor series loss resistance
overall Q at resonance
3db BW at resonance

All of the programs on that site were written in Pascal, and run in a DOS
window. The author (Reg G4FGQ) is now a silent key. One of his friends now
maintains the archive of his developments.

Cheers,
--
David
dgminala at mediacombb dot net

Resonance Frequency of a parallel RC/RL circuit - Expression.png (1/1)
 

amdx wrote:
"Fred Abse" wrote in message
On Sun, 17 Oct 2010 16:54:53 -0500, Tim Williams wrote:

For an LC circuit, yes. For a damped RLC (series or parallel), there's
an
L/R or RC time constant which reduces it. This is called the
pseudofrequency.

Only in the parallel case.

I went 100 deep with Google looking for a "Resonant frequency Calculator"
that
allows individual -capacitor loss resistance- and -inductor loss
resistance-, or Q
of the individual cap and inductor. Didn't have any luck.
Anyone know of an online calculator that puts all of phantom at aol's
formula
behind a few for inputs and buttons.

No, but I found a reactance calculator:
http://www.daycounter.com/Calculator...lculator.phtml
which you could use in tandem with the RFC and then the Q is related
to that and the resistive R by some formula that I've left as an exercise
for the reader. ;-)

(I'm pretty sure it's something really simple, like X/R or something.)

Hope This Helps!
Rich

Resonance Frequency of a parallel RC/RL circuit - Expression.png (1/1)
 

On Mon, 13 Dec 2010 10:12:51 -0600, "amdx" wrote:

SNIP

I went 100 deep with Google looking for a "Resonant frequency Calculator"
that
allows individual -capacitor loss resistance- and -inductor loss
resistance-, or Q
of the individual cap and inductor. Didn't have any luck.
Anyone know of an online calculator that puts all of phantom at aol's
formula
behind a few for inputs and buttons.
MikeK.


I did some simplification of the expressions and here they a

http://img258.imageshack.us/img258/1...rallelrlrc.png

The expressions for the zero phase angle frequency and impedance magnitude
became quite simple, and are probably the most interesting case also.

Resonance Frequency of a parallel RC/RL circuit - Expression.png (1/1)
 

Hmm, you seem to have lost the subscripts past equation 2?

Also, the opening magnitude symbol on the last line ("|Z|") is purple,
which is weird. Come to look at it, blue letters are used occasionally in
equations 1 and 2, and the "impedance /is/" of the 5th line is italic and
green.

Oh well. It's not LaTeX :)

Do you have an accompanying circuit? Are they both ESR, or is RL in
parallel (i.e., loss instead of DCR)? Funny thing is, depending on how
you wind it, both DCR and loss may be significant, whereas most capacitors
don't suffer from noticable dielectric loss.

I like how "resonance" (in either case) ends up as Fo times a correction
factor.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

"Phantom" wrote in message
...
On Mon, 13 Dec 2010 10:12:51 -0600, "amdx" wrote:

SNIP

I went 100 deep with Google looking for a "Resonant frequency
Calculator"
that
allows individual -capacitor loss resistance- and -inductor loss
resistance-, or Q
of the individual cap and inductor. Didn't have any luck.
Anyone know of an online calculator that puts all of phantom at aol's
formula
behind a few for inputs and buttons.
MikeK.


I did some simplification of the expressions and here they a

http://img258.imageshack.us/img258/1...rallelrlrc.png

The expressions for the zero phase angle frequency and impedance
magnitude
became quite simple, and are probably the most interesting case also.

Resonance Frequency of a parallel RC/RL circuit - Expression.png (1/1)
 

On Sat, 18 Dec 2010 13:54:32 -0600, "Tim Williams"
wrote:

Hmm, you seem to have lost the subscripts past equation 2?

Also, the opening magnitude symbol on the last line ("|Z|") is purple,
which is weird. Come to look at it, blue letters are used occasionally in
equations 1 and 2, and the "impedance /is/" of the 5th line is italic and
green.

Oh well. It's not LaTeX :)

Do you have an accompanying circuit?

The circuit was described elsewhere; it's a series combination of a resistor RL
and an inductance L, in parallel with another series combination of a resistor
RC and a capacitor C.

Are they both ESR, or is RL in
parallel (i.e., loss instead of DCR)? Funny thing is, depending on how
you wind it, both DCR and loss may be significant, whereas most capacitors
don't suffer from noticable dielectric loss.

I like how "resonance" (in either case) ends up as Fo times a correction
factor.

I did that on purpose. Notice how for the zero phase angle case you can easily
see that if RC=RL, then the multiplying factor becomes 1.


Tim