[Iain Churches[_2_]]

There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...alculator.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.


Best regards
Iain

[Patrick Turner]

Iain Churches wrote:

There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...alculator.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Best regards
Iain

Right at the beginning you start with a parallel R&C network and you
say...

" The reactance X of the capacitor at any particular frequency can be
calculated with the equation:
1/(2 x Pi x F x C) "

More simply, XC in ohms = 1 / ( 6.28 x F x C ) where F is in Hertz, and
C is in Farads.

From this you get an easier equation,

XC = 159,000 / ( F x C ) where F is in Hertz, C is in uF.

You need to state what the units are. Beginners have NO CLUE!!!!!.....

Then you have...

" The voltage is constant and the current is the sum of the vectors. "

Hands up anyone who knows what that means? Nobody? I thought so.

"The impedance Z of the network can be calculated by (R x
Xc)/(R^2+Xc^2)^0,5"

Huh????? is that

(R x XC) / square root of ( R squared + XC squared ), with R in ohms,
and XC in ohms?

Again, spell it out more clearly for beginners.

The phase angle of the impedance is given by: Theta = arctan (Xc/R)
=-90+DEGREES(ATAN(E10/$G$4))

Huh???????????????

Could you please explain, as they do in good books, in a page, with
diagrams if needed, exactly what
you mean and explain how to use a calculator to get an answer and say
under what typical circumstances
in a circuit the answer is meaningful, and give a typical response
example graph for an R&C circuit
with in / out impedance quantities. Include phase shift of the output
signal
and input signal source resistance.

Or, leave all the detail out and just make the formula simple, and refer
to a good URL where
the detail you probably don't undersand fully IS explained.

"The change in dB in either voltage V or current I with respect to the
impedance at the first frequency measured can be caculated by:
20log(Z2/Z1) where Z1 is the impedance at the first measured frequency
and Z2 at the frequency being considered."

What is the first frequency? the one that won a race? came top of the
class?
Please explain poles, and -3dB points in responses......

You have Z1, and Z2. What are they? above you have XC and R.

Its VERY confusing to a beginner.

My simple advice is that you COMPARE what you are saying with EACH and
every sentence and letter and word
with what is said in good text books such as RDH4 et all, and check that
YOU
understand the concepts fully, so that your page saying what has been
said in many text books
already, but perhaps not much online has some real eloquence from which
others can learn the very basic R&C issues
without needing to read a book.

A useful example for parallel R&C...

Where R = XC, then the impedance of the TWO together in a circuit =
0.707 x R.

And for a series R&C, where R = XC, Z in a circuit = 1.414 x R.

In cases where R&C networks are used for example in tone controls,
amp stabilizing networks, or phono eq networks, the source resistance or
any other resistance needs to be
taken into consideration, and this immediately makes things much more
complicated to work out for the
beginner, so much so that for a wanted response outcome, beginners will
just fiddle the R&C values around by trial and error until the wanted
response
is achieved, or the wanted degree of stability is achieved, even though
the pole frequencies
of the network are not known, and not calculated.

For example, one may consider a triode to have a low enough Ra to be
called a voltage source.
Say we have 100k feeding 0.1uF, and the voltage across the 0.1uF is the
output voltage
and feeds a very high resistance, say the grid of another tube.

The R&C for a LPF,
and the pole is at 159,000 / ( 100,000 x 0.1 ) = 15.9Hz.

At the pole, R = ZC.

Input impedance at 15.9H = 141,400 ohms.

Below 15.9H, Zin rises to infinity, and above it falls to a minimum of
100k.




Patrick Turner

[Iain Churches[_2_]]

"Patrick Turner" wrote in message
...


Iain Churches wrote:

There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...alculator.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.


Right at the beginning you start with a parallel R&C network and you
say...

" The reactance X of the capacitor at any particular frequency can be
calculated with the equation:
1/(2 x Pi x F x C) "

More simply, XC in ohms = 1 / ( 6.28 x F x C ) where F is in Hertz, and
C is in Farads.

From this you get an easier equation,

XC = 159,000 / ( F x C ) where F is in Hertz, C is in uF.

You need to state what the units are. Beginners have NO CLUE!!!!!.....

Patrick. Thanks for your reply.
As I said in my post about the page, it is still under construction.
I am grateful for any suggestions for improvement from people
on this group. I will clarify the units, as you suggest. That's a good
start.

My web-space is limited, so it was necessary to assume some
level of experience and backgrpound knowledge from the reader.
The page is intended to assist those who might be working out
RC values for stability networks. This is not usually what
beginners do:-)

To use the spreadhseet, you do not have to understand the
mathematics of how and what it calculates. That's the whole
point, and the advantages of the graph plotting properties of
Excel. Did you downlod the spreadsheet and try some
entries?

As I say, some degree of familiarity with the concept of
series and parallel circuits must be assumed, but the point it
that the phase makes the calculations more complex than if
we had two Rs in series or in parallel.

The page is probably of little use to a beginner. It is not
intended to be. I would not expect as a musicologist to
be discussing the piano concerti of Rachmaninov
with a first year pupil who is still mastering the basics of
Tonic Sol-fa.


Then you have...

" The voltage is constant and the current is the sum of the vectors. "

Hands up anyone who knows what that means? Nobody? I thought so.


Several people proof-read the page. They all understoood what was
meant. I will try and add some more text for claification.

"The impedance Z of the network can be calculated by (R x
Xc)/(R^2+Xc^2)^0,5"

Huh????? is that

(R x XC) / square root of ( R squared + XC squared ), with R in ohms,
and XC in ohms?

Again, spell it out more clearly for beginners.

The formula is written in the format that Excel uses.

The phase angle of the impedance is given by: Theta = arctan (Xc/R)
=-90+DEGREES(ATAN(E10/$G$4))

Huh???????????????

Again, this is the format used by Excel. E10, $G$4 refer to cells
within the spreadsheet. The $ sign locks the relative reference.

Could you please explain, as they do in good books, in a page, with
diagrams if needed, exactly what
you mean and explain how to use a calculator to get an answer

The Excel spreadsheet is your calculator, you need no other.

and say
under what typical circumstances
in a circuit the answer is meaningful, and give a typical response
example graph for an R&C circuit
with in / out impedance quantities. Include phase shift of the output
signal
and input signal source resistance.

Or, leave all the detail out and just make the formula simple, and refer
to a good URL where
the detail you probably don't undersand fully IS explained.


"The change in dB in either voltage V or current I with respect to the
impedance at the first frequency measured can be caculated by:
20log(Z2/Z1) where Z1 is the impedance at the first measured frequency
and Z2 at the frequency being considered."


What is the first frequency? the one that won a race? came top of the
class?

Z1 is the first frequency in the column, 10Hz. It is used as an anchor
for the phase plot, and is clearly labelled.

Please explain poles, and -3dB points in responses......

You have Z1, and Z2. What are they? above you have XC and R.

Its VERY confusing to a beginner.

If you have any ideas how it may be expressed more
simply in the limited space I have, I would be pleased
to hear your suggestions.

My simple advice is that you COMPARE what you are saying with EACH and
every sentence and letter and word
with what is said in good text books such as RDH4 et all, and check that
YOU
understand the concepts fully, so that your page saying what has been
said in many text books
already, but perhaps not much online has some real eloquence from which
others can learn the very basic R&C issues
without needing to read a book.

A useful example for parallel R&C...

Where R = XC, then the impedance of the TWO together in a circuit =
0.707 x R.

Yes. The spreadsheet calculates correctly for such an example.
Did you download and try it?

And for a series R&C, where R = XC, Z in a circuit = 1.414 x R.

Indeed it is. But it is probably not too common in a network for
R to equal XC, and I was trying, as simply as possible to bring the
point home that the reactance of an RC conbination cannot be
calculated as if it were a pair of resistors.

In cases where R&C networks are used for example in tone controls,
amp stabilizing networks, or phono eq networks, the source resistance or
any other resistance needs to be
taken into consideration, and this immediately makes things much more
complicated to work out for the
beginner, so much so that for a wanted response outcome, beginners will
just fiddle the R&C values around by trial and error until the wanted
response
is achieved, or the wanted degree of stability is achieved, even though
the pole frequencies
of the network are not known, and not calculated.

Most beginners, and a fair percentage of experiences builders copy things
like tone stacks from published circuits, or use the PD software available
on the web.


Thanks for your comments.
Any ideas you may have for further explanation and
clarification would be appreciated.

Best regards
Iain

[Ian Thompson-Bell]

Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...alculator.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.


Best regards
Iain


Just a couple of comments as Patrick seems to have done a comprehensive
job as usual.

First, in the intro you talk about series RC circuits and then show a
picture of a parallel one. I would suggest doing the series case first.

Second, to be totally accurate when you mention the impedance and phase
of the networks you should say the 'magnitude' of the impedance.

And yes, I did understand the bit about adding vectors!

Cheers

Ian

[BretLudwig]

Nothing beats, where possible, going to school and being in a class
environment doing this. That isn't always possible and you can learn on
your own but in the US there are cheap community college classes.

One useful resource;

http://www.allaboutcircuits.com/

Also helpful:


http://www.pmillett.com/Books/Hartley_Audio.pdf
http://www.pmillett.com/Books/lauer_radio_eng.pdf
http://www.pmillett.com/Books/Happell_engineering.pdf

US Navy rate training manuals and the ARRL Handbooks are useful also.



--
Message posted using http://www.talkaboutaudio.com/group/rec.audio.tubes/
More information at http://www.talkaboutaudio.com/faq.html

[keithr]

"Patrick Turner" wrote in message
...


Iain Churches wrote:

There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...alculator.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Best regards
Iain

Right at the beginning you start with a parallel R&C network and you
say...

" The reactance X of the capacitor at any particular frequency can be
calculated with the equation:
1/(2 x Pi x F x C) "

More simply, XC in ohms = 1 / ( 6.28 x F x C ) where F is in Hertz, and
C is in Farads.

Uh, isn't 6.28 an approximation of 2*Pi? I don't think that anybody who
doesn't know what Pi is is going to get anything out of all this math
anyway.

From this you get an easier equation,

XC = 159,000 / ( F x C ) where F is in Hertz, C is in uF.

You need to state what the units are. Beginners have NO CLUE!!!!!.....

Then you have...

" The voltage is constant and the current is the sum of the vectors. "

Hands up anyone who knows what that means? Nobody? I thought so.

Teacher! Teacher! My hand is up and I suspect that a lot of others are too


"The impedance Z of the network can be calculated by (R x
Xc)/(R^2+Xc^2)^0,5"

Huh????? is that

snip

Patrick Turner

It all depends what the intent of Iain's work is - an assistance for people
designing their own circuits or a beginners introduction to electronics. Not
every work has to start from first principles.

Keith

[Iain Churches[_2_]]

"keithr" wrote in message
...


It all depends what the intent of Iain's work is - an assistance for
people designing their own circuits or a beginners introduction to
electronics. Not every work has to start from first principles.


It was originally intended for my own use, but then
given to colleagues who expressed an interest in it.

It is a tool, a calculator which can establish impedance
across the audio band (10Hz to 100kHz) and plot the
all values simultaneously, and present them as a graph
which can be printed.

I did not present it as a "black box", or hide any cells,
but gave on the web page the formulae which the sheet
uses for its calculations. These were written in the format
which the Excel spreadsheet uses. One does not
necessarily need to be familiar with the formulae to use
the spreadsheet..

Regards to all
Iain

[Iain Churches[_2_]]

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...alculator.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a feeling that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

First, in the intro you talk about series RC circuits and then show a
picture of a parallel one. I would suggest doing the series case first.

Thanks. I will take a llook at the order.

Second, to be totally accurate when you mention the impedance and phase of
the networks you should say the 'magnitude' of the impedance.

Thanks for that too. I will make the alteration today.

And yes, I did understand the bit about adding vectors!

I never for a moment suspected that you would not:-)
Did you actually run the spreadsheet?

Cheers
Iain

[Ian Thompson-Bell]

Iain Churches wrote:
"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...alculator.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a feeling that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

Neither do I have or use Excel but it loads fine into Open Office which
is free and runs on both Windows and Linux.

First, in the intro you talk about series RC circuits and then show a
picture of a parallel one. I would suggest doing the series case first.

Thanks. I will take a llook at the order.

Second, to be totally accurate when you mention the impedance and phase of
the networks you should say the 'magnitude' of the impedance.

Thanks for that too. I will make the alteration today.
And yes, I did understand the bit about adding vectors!

I never for a moment suspected that you would not:-)
Did you actually run the spreadsheet?

Yes, it seems to work fine.

Cheers

[Patrick Turner]

Iain Churches wrote:

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...alculator.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a feeling that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

What you are saying in the introduction now looks better, but technical
mumbo jumbo
nobody here understands is still there to confuse.

I tried downloading the little program and it displayed OK but when I
clicked
to position the cursor into the value boxes for different values for R
or C it wouldn't let me
type new values in.

I can't find the starter button.

I am hopelessly lost with simple things on a PC, and really only happy
with triodic farnarkulations.

Anyway, a program that tells you just what the R&C impedance is is quite
OK except that
without a lot more knowledge about networks, people will use the answers
they get wrongly
when there are more items connected besides the R and the C.

A classic example is the passive RIAA network.

Many arguments have erupted over this little item, with many saying
one cannot get a flat response with all the eq done in one go.

People want such impedance values to estimate a response curve, not
just because they are aimlessly curious.
They want to be able to build something, and measure what they have
previously calculated,
or know that if they use exactly the calculated values, the circuit will
be right without
measuring it after they have connected it up.

But I always check every darn thing, and I never assume my calculations
are perfect.
And I never assume the values of R or C out of the box is dead right
either,
so even if you do calculate perfectly, you still will have to trim the
results
with adjusted values of R and C .
RIAA and tone controls require this discipline.

In stabilizing amps unconditionally but maximizing resistive load
response
simultaneously, I rarely calculate anything because I cannot know the
many interacting
reactance values accurately. I know reactances are there though.
So stabilizing is all done by trial and error and by observation with a
CRO
and use of a radio tuning cap and a series pot to get the shelving
circuit right
to reduce HF open loop gain and phase shift.

I sometimes calculate R&C Zobel networks, and at what F the Z(R+C) =
1.41 x R, or beginning to rapidly
become mainly resistive. One doesn't want the Zobel network
begin to load the amp at too low an F.


Patrick Turner.



First, in the intro you talk about series RC circuits and then show a
picture of a parallel one. I would suggest doing the series case first.

Thanks. I will take a llook at the order.

Second, to be totally accurate when you mention the impedance and phase of
the networks you should say the 'magnitude' of the impedance.

Thanks for that too. I will make the alteration today.

And yes, I did understand the bit about adding vectors!

I never for a moment suspected that you would not:-)
Did you actually run the spreadsheet?

Cheers
Iain

[John Byrns]

In article ,
Patrick Turner wrote:

Iain Churches wrote:

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...edanceCalculat
or.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a feeling that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

What you are saying in the introduction now looks better, but technical
mumbo jumbo
nobody here understands is still there to confuse.

What "mumbo jumbo" are you talking about? I haven't read the entire
page carefully enough to say that I have proofread it, but it looks
straight forward and easy enough to understand to me. The math is quite
simple and is not rocket science.

My main complaint are the second and third sentences which introduce the
parallel RC network but then try their best to confuse us by presenting
an example of the application of a series RC network.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Iain Churches[_2_]]

"John Byrns" wrote in message
...
In article ,
Patrick Turner wrote:

Iain Churches wrote:

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...edanceCalculat
or.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a
comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a feeling
that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

What you are saying in the introduction now looks better, but technical
mumbo jumbo
nobody here understands is still there to confuse.

What "mumbo jumbo" are you talking about? I haven't read the entire
page carefully enough to say that I have proofread it, but it looks
straight forward and easy enough to understand to me.

I gave it to several people to read before posting the link. None of them
found it difficult to read. I do take Patrick's point about defining units,
and have made some additions. I would have thought that most people
interested in tube audio would be familiar with the constant Pi (not Pie,
or Pye, Patrick:-) but all the same I have added its value.

The format in which the formulae are written is that used by Excel.


The math is quite
simple and is not rocket science.

My main complaint are the second and third sentences which introduce the
parallel RC network but then try their best to confuse us by presenting
an example of the application of a series RC network.

I have now made some changes. I would be grateful if you would
take another look John, and tell me if, in your opinion, the opening
sentences are now clearer.

Thanks for your help.
Best regards

Iain

[Iain Churches[_2_]]

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...alculator.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a feeling that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

What you are saying in the introduction now looks better, but technical
mumbo jumbo
nobody here understands is still there to confuse.

I am a little confused as to what you mean by mumbo jumbo.
Please explain. I have chaged the some of the text around to improve
the readability, and taken out the cell references to the spreadsheet which
were made prematurely, before the spreadsheet concept for calculating
RC netowork values had been introduced.



I tried downloading the little program and it displayed OK but when I
clicked
to position the cursor into the value boxes for different values for R
or C it wouldn't let me
type new values in.

I and others have tried it in various Excel cersions from 2003 onward.
All work correctly. Ian opened the spreadsheet in Open Office, and
reports that it worked OK. He did not say if he was able to see the
graphs. I must ask him.

I can't find the starter button.

There is no starter button. The spreadsheet has sumultaneous
combustion in all fuel cells:-)

I am hopelessly lost with simple things on a PC, and really only happy
with triodic farnarkulations.

It seemed to me that the benefit of such a spreadhseet was that it
would caculate not just one value, at a specific frequency, but a whole
range of values from 10Hz to 100kHx for a particular RC combination.


Anyway, a program that tells you just what the R&C impedance is is quite
OK except that
without a lot more knowledge about networks, people will use the answers
they get wrongly
when there are more items connected besides the R and the C.

Understood. My original idea was to find a step forward from the
empirical pair of decade boxes which most people seem to use.

A classic example is the passive RIAA network.

Many arguments have erupted over this little item, with many saying
one cannot get a flat response with all the eq done in one go.

It is a long time since I read the Lipschitz paper. Most authors seem
to be of the opinion that the "all in one" solution is not good. The good
generic studio RIAA designs had 318µS and 3180µS together with
75µS implemented separately. This was done for instance on the Decca
circuit. The only "all in one" that I have experience with is a published
RCA design. I know several people who have built it. It sounds awful.


People want such impedance values to estimate a response curve, not
just because they are aimlessly curious.

They want to be able to build something, and measure what they have
previously calculated,
or know that if they use exactly the calculated values, the circuit will
be right without
measuring it after they have connected it up.

That is precisely what the spreadsheet graphs do.

This is a useful discussion Patrick.Thanks for your comments

Regards
Iain

[Iain Churches[_2_]]

"Ian Thompson-Bell" wrote in message
...

http://www.kolumbus.fi/iain.churches...alculator.html


Neither do I have or use Excel but it loads fine into Open Office which is
free and runs on both Windows and Linux.

A colleague of mine who tried to run the spreadsheet in Open Office
reports that the sheet itself worked perfectly but he could not access
the graphs. There were no tabs at the bottom of the sheet, as there
would be in Excel. It may be that he was using an earlier version of
Open Office. Could you tell me please Ian which version you use,
and if you could open the graphs made by the calculator.

Thanks for your help.
Regards
Iain

[Ian Thompson-Bell]

Iain Churches wrote:
"Ian Thompson-Bell" wrote in message
...
http://www.kolumbus.fi/iain.churches...alculator.html


Neither do I have or use Excel but it loads fine into Open Office which is
free and runs on both Windows and Linux.

A colleague of mine who tried to run the spreadsheet in Open Office
reports that the sheet itself worked perfectly but he could not access
the graphs. There were no tabs at the bottom of the sheet, as there
would be in Excel. It may be that he was using an earlier version of
Open Office. Could you tell me please Ian which version you use,
and if you could open the graphs made by the calculator.


I am using Open Office 2.3 and the tabs show and the graphs work. I also
tried it with Gnumeric, a Linux only spreadsheet program and they all
work fine with that too.

Cheers

Ian

[Patrick Turner]

John Byrns wrote:

In article ,
Patrick Turner wrote:

Iain Churches wrote:

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...edanceCalculat
or.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a feeling that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

What you are saying in the introduction now looks better, but technical
mumbo jumbo
nobody here understands is still there to confuse.

What "mumbo jumbo" are you talking about? I haven't read the entire
page carefully enough to say that I have proofread it, but it looks
straight forward and easy enough to understand to me. The math is quite
simple and is not rocket science.

Reactive network math is anything but easily understandable.

Iain has....

"The voltage is constant and the current is the sum of the vectors."

Nobody I know ever works out vectors. Nobody I know has a clue....
I don't, as a result, and its because I don't have to.


"The impedance Z of the network can be calculated by (R x
Xc)/(R^2+Xc^2)^0,5"

This is written to appear confusing to 99% of any beginner.

"The phase angle of the impedance is given by: Theta = arctan (Xc/R)
=-90+DEGREES(ATAN(Xc/R))"

Another completely incomprehensible formula that nobody uses, or can
understand.

What ppl CAN understand is simpler.

You always must have a SIMPLE REAL WORLD MODEL and application of a
circuit before understanding is at all possible
or useful.

1. So, there MUST be a broad bandwidth signal source, so assume a
voltage source with 0.0 ohms output resistance.

2. Assume this signal source does in fact have some source resistance,
so add a series R to represent it.

3. The output of the source resistance is the input to whatever network
you have.

4. The source resistance becomes part of the network whether you like it
or not
as the input terminal resistance and must be allowed for in
calculations.

5. There is an output terminal after the network from which a frequency
response is measured
always by a CRO probe or voltmeter such high input resistabce or
impedance that
the response of the network isn't affected.

6. There will be some real value of terminating resistance and or
reactance between output and 0V
after the network output.

7. The terminating impedance also becomes part of the network and
affects the way the network operates.

8. To establish what the response is of a network its teribly difficult
to calculate correctly
taking all the above into consideration.

9. Just build the damn network, knowing what the Rout of your sig gene
is, and measure it.

10. Adjust R&C values until you can plot the response you want.

11. Prove to yourself that only a guess can be made about real responses
easily.

12. Learn that hands on real world work in the darn workshop solves
problems.

13. And don't be afraid to simulate so that the risk of making a mistake
in a calculation is eliminated.

14. This leaves the possibility of making a mistake due to non inclusion
of some
factor.

15. Something is dead right when what you measure is exactly the same as
what you correctly calculate
and what you correctly simulate.

When a textbook is attempted to be written, the author does well to
assume his readers have low IQ,
and are insufferably dumb, and need everything all spelled out in easily
applicable layman's terms.

RDH4 is halfway there in many respects.

But many text books don't teach anything; they just confuse, and assume
the poor reader
has learnt it all elsewhere by miracle.


There are some of the concerns that should be in EVERYONE'S mind when
they have to build a network
to fiddle around with an amplifier response in any way.

Patrick Turner


My main complaint are the second and third sentences which introduce the
parallel RC network but then try their best to confuse us by presenting
an example of the application of a series RC network.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Patrick Turner]

Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:

snip

I tried downloading the little program and it displayed OK but when I
clicked
to position the cursor into the value boxes for different values for R
or C it wouldn't let me
type new values in.

I and others have tried it in various Excel cersions from 2003 onward.
All work correctly. Ian opened the spreadsheet in Open Office, and
reports that it worked OK. He did not say if he was able to see the
graphs. I must ask him.

I can't find the starter button.

There is no starter button. The spreadsheet has sumultaneous
combustion in all fuel cells:-)

I am hopelessly lost with simple things on a PC, and really only happy
with triodic farnarkulations.

You didn't answer my question and I cannot use the spreadsheet as a
tool.

But I found any sort of program to simulate schematics also had me
stumped.

So **** 'em, I damn well get by very well without any of that, and I be
like
my father's generation and just work it out the old fashioned way.



Patrick Turner.

snip

[Iain Churches[_2_]]

"Ian Thompson-Bell" wrote in message
...

http://www.kolumbus.fi/iain.churches...alculator.html


I am using Open Office 2.3 and the tabs show and the graphs work. I also
tried it with Gnumeric, a Linux only spreadsheet program and they all work
fine with that too.

Thanks Ian for confirming. Your Open Office is probably the current
version. The only other compatibility problem seems to be with
Microsoft Works, where early versions can open the spreadsheet
which functions correctly, but do not show the tabs for the charts.

Regards
Iain

[Iain Churches[_2_]]

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"Patrick Turner" wrote in message
...

I tried downloading the little program and it displayed OK but when I
clicked
to position the cursor into the value boxes for different values for R
or C it wouldn't let me
type new values in.

I and others have tried it in various Excel cersions from 2003 onward.
All work correctly. Ian opened the spreadsheet in Open Office, and
reports that it worked OK. He did not say if he was able to see the
graphs. I must ask him.

I can't find the starter button.

There is no starter button. The spreadsheet has sumultaneous
combustion in all fuel cells:-)

I am hopelessly lost with simple things on a PC, and really only happy
with triodic farnarkulations.

You didn't answer my question and I cannot use the spreadsheet as a
tool.

If your question was about the starter button, then there is none.
The calculations are instantaneous, as soon as you press Enter.

You don't seem to be able to run Excel.

Did you acces the calculator from the link at the very bottom
of the page? It says:

Download at: RC Impedance Calculator


Ian reports that the spreadsheet works also in Open Office 2.3
and the tabs show and the graphs work. He also tried it with
Gnumeric, a Linux only spreadsheet program and they all
work fine with that too. The only compatibility problems seem
to be with early versions of Microsoft Works, in which the
spreadsheet opens and works correctly but the tabs which give
access to the graphics do not appear.


Regards
Iain

[Patrick Turner]

Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"Patrick Turner" wrote in message
...

I tried downloading the little program and it displayed OK but when I
clicked
to position the cursor into the value boxes for different values for R
or C it wouldn't let me
type new values in.

I and others have tried it in various Excel cersions from 2003 onward.
All work correctly. Ian opened the spreadsheet in Open Office, and
reports that it worked OK. He did not say if he was able to see the
graphs. I must ask him.

I can't find the starter button.

There is no starter button. The spreadsheet has sumultaneous
combustion in all fuel cells:-)

I am hopelessly lost with simple things on a PC, and really only happy
with triodic farnarkulations.

You didn't answer my question and I cannot use the spreadsheet as a
tool.

If your question was about the starter button, then there is none.
The calculations are instantaneous, as soon as you press Enter.

You don't seem to be able to run Excel.

I don't have a clue if I can or not.

My PC is a 2003 model with standard domestic Windows XP.

I do not want to have to pay for a special program ability to calculate
RC network Z values, because the formulas I have are from old books and
my brain combined with a
pocket calculator does very well thank you.



Did you acces the calculator from the link at the very bottom
of the page? It says:

Download at: RC Impedance Calculator

That's what I did and the PC went through motions of instalation
and saving in my audio technical folder in a newly created file for it.

I open up the downloaded file and the window displayed as it should
have, but
It wasn't active. Just as useful as a dead cat.


Ian reports that the spreadsheet works also in Open Office 2.3
and the tabs show and the graphs work. He also tried it with
Gnumeric, a Linux only spreadsheet program and they all
work fine with that too. The only compatibility problems seem
to be with early versions of Microsoft Works, in which the
spreadsheet opens and works correctly but the tabs which give
access to the graphics do not appear.

If its too much trouble, I delete the damn thing, and
carry on as I have for years without it....

I like mucking around with amps or being out on my bicycle.

Sitting glued to the PC to perform in hours what i do
in 20 seconds in the workshop doesn't make my life easier.

The PC is a slave to me; I am not its slave.

Patrick Turner.

Regards
Iain

[John Byrns]

In article ,
"Iain Churches" wrote:

"John Byrns" wrote in message
...
In article ,
Patrick Turner wrote:

Iain Churches wrote:

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...ImpedanceCalcu
lat
or.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a
comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a feeling
that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

What you are saying in the introduction now looks better, but technical
mumbo jumbo
nobody here understands is still there to confuse.

What "mumbo jumbo" are you talking about? I haven't read the entire
page carefully enough to say that I have proofread it, but it looks
straight forward and easy enough to understand to me.

I gave it to several people to read before posting the link. None of them
found it difficult to read. I do take Patrick's point about defining units,
and have made some additions. I would have thought that most people
interested in tube audio would be familiar with the constant Pi (not Pie,
or Pye, Patrick:-) but all the same I have added its value.

The format in which the formulae are written is that used by Excel.

The math is quite
simple and is not rocket science.

My main complaint are the second and third sentences which introduce the
parallel RC network but then try their best to confuse us by presenting
an example of the application of a series RC network.

I have now made some changes. I would be grateful if you would
take another look John, and tell me if, in your opinion, the opening
sentences are now clearer.

They haven't changed as far as I can see. What I object to are the
following two sentences, "Let's start with the parallel combination. A
common example seeen often in schematics*is the series RC combination in
parallel with the anode (plate) resistor on the first stage." It starts
talking about "the parallel combination", then cites as an example "the
series RC combination", then shows the diagram of a "RC Parallel
Network" before going into the discussion of parallel RC networks. What
I find confusing is the example given of a series RC network in the
middle of the discussion of parallel RC networks. A better example to
cite at that point would be that of a parallel RC network used as a low
frequency gain stepping network.

You also present the following formula:
"Theta = arctan (Xc/R)* =-90+DEGREES(ATAN(Xc/R))"
This formula is wrong on the face of it as the second equality sign
equates two quantities that are obviously not equal by inspection. This
equation essentially makes the claim that 0 = 90.

IIRC the first part of the equation, "Theta = arctan (Xc/R)" is correct
for the phase angle of an impedance, but the rest is not correct.

By the way I found one slight bug in your spread sheet. When I entered
Zero for the resistance value, the spread sheet blew up with errors.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Doug Bannard]

"Patrick Turner" wrote in message
...


John Byrns wrote:

In article ,
Patrick Turner wrote:

Iain Churches wrote:

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...edanceCalculat
or.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a
comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a feeling
that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

What you are saying in the introduction now looks better, but technical
mumbo jumbo
nobody here understands is still there to confuse.

What "mumbo jumbo" are you talking about? I haven't read the entire
page carefully enough to say that I have proofread it, but it looks
straight forward and easy enough to understand to me. The math is quite
simple and is not rocket science.

Reactive network math is anything but easily understandable.

Iain has....

"The voltage is constant and the current is the sum of the vectors."

Nobody I know ever works out vectors. Nobody I know has a clue....
I don't, as a result, and its because I don't have to.


"The impedance Z of the network can be calculated by (R x
Xc)/(R^2+Xc^2)^0,5"

This is written to appear confusing to 99% of any beginner.

"The phase angle of the impedance is given by: Theta = arctan (Xc/R)
=-90+DEGREES(ATAN(Xc/R))"

Another completely incomprehensible formula that nobody uses, or can
understand.

What ppl CAN understand is simpler.

You always must have a SIMPLE REAL WORLD MODEL and application of a
circuit before understanding is at all possible
or useful.

1. So, there MUST be a broad bandwidth signal source, so assume a
voltage source with 0.0 ohms output resistance.

2. Assume this signal source does in fact have some source resistance,
so add a series R to represent it.

3. The output of the source resistance is the input to whatever network
you have.

4. The source resistance becomes part of the network whether you like it
or not
as the input terminal resistance and must be allowed for in
calculations.

5. There is an output terminal after the network from which a frequency
response is measured
always by a CRO probe or voltmeter such high input resistabce or
impedance that
the response of the network isn't affected.

6. There will be some real value of terminating resistance and or
reactance between output and 0V
after the network output.

7. The terminating impedance also becomes part of the network and
affects the way the network operates.

8. To establish what the response is of a network its teribly difficult
to calculate correctly
taking all the above into consideration.

9. Just build the damn network, knowing what the Rout of your sig gene
is, and measure it.

10. Adjust R&C values until you can plot the response you want.

11. Prove to yourself that only a guess can be made about real responses
easily.

12. Learn that hands on real world work in the darn workshop solves
problems.

13. And don't be afraid to simulate so that the risk of making a mistake
in a calculation is eliminated.

14. This leaves the possibility of making a mistake due to non inclusion
of some
factor.

15. Something is dead right when what you measure is exactly the same as
what you correctly calculate
and what you correctly simulate.

When a textbook is attempted to be written, the author does well to
assume his readers have low IQ,
and are insufferably dumb, and need everything all spelled out in easily
applicable layman's terms.

RDH4 is halfway there in many respects.

But many text books don't teach anything; they just confuse, and assume
the poor reader
has learnt it all elsewhere by miracle.


There are some of the concerns that should be in EVERYONE'S mind when
they have to build a network
to fiddle around with an amplifier response in any way.

Patrick Turner


My main complaint are the second and third sentences which introduce the
parallel RC network but then try their best to confuse us by presenting
an example of the application of a series RC network.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

Well Iain, your spreadsheet works well for me and I think that you've done a
fine job subject to the changes that both Patrik and John Byrns have
suggested regarding defining your units.

As far as the remainder of Patrick's comments are concerned however, I'd
like to make a few of my own:

1) Reactive network math is really not at all difficult. The key to
understanding it is to be able to draw the vector (actually called phasor)
diagram for the circuit under consideration. If you find this difficult to
do, it is simply because you have not received the appropriate instruction
on the subject, and this is easily rectified. There are many books
available, but IMHO, one of the better ones is entitled "Introduction to
Electric Circuits" by Herbert W Jackson. This is still in print, is written
(unlike so many EE texts) to be easily understood, and is ideal for
self-study. Another excellent book which should be bought at the same time
is "Electric Circuits" by Joseph A Edminister, also still in print I
believe. This second book is a Schaum's Outline Series book and contains
hundreds of solved example problems.

2) Iain's spreadsheet is a very useful tool which allows you to evaluate
these networks without the need to resort to the math, and without having to
look up some "cookbook" formula to solve a problem. Take advantage of it.
The use of tools like spreadsheets on your PC should actually speed up your
calculations, minimize the chances of errors, and free you up to spend more
time in your shop!


Regards: Doug Bannard

[Paul[_11_]]

On Fri, 23 May 2008 09:39:34 GMT, Patrick Turner
wrote:

.....snip!....

You don't seem to be able to run Excel.

I don't have a clue if I can or not.

My PC is a 2003 model with standard domestic Windows XP.

I do not want to have to pay for a special program ability to calculate
RC network Z values, because the formulas I have are from old books and
my brain combined with a
pocket calculator does very well thank you.


Hi Patrick, I know how you feel. I have taught AC and DC electronics
(plus semiconductors, digital, Linux, networking, soldering, etc) to
1st and 2nd year college students for about 8 years, now. In my
opinion, yes, you can get away with the old formulae, a handy
calculator, and having a "feel" for the circuits (if you've been
building them long enough).
The question is, at what point to do you have to go through the
agony of learning vectors, complex numbers, reactance, etc? Every year
my students go through the same misery. It's tough if you have never
seen this stuff before. I would say the AC course is the toughest we
put the students through. It's not tough mathematically, it's just
that it is so weird, and difficult to relate to.
You do have to take "little baby steps" when you learn AC circuits.
Having to deal with some of the final formulas and concepts are just
too alien to really understand without the basic background.
What's in it if you finally understand the stuff? First off, simple
phase and amplitude problems are easy to solve. (They were before if
you used your textbook formulae). More complex circuits, especially
when inductance is thrown in, are now easier to deal with. You can
make sense out of Zoebel networks. Things like power factor, leakage
inductance, resonance, RF circuits, tank circuits , filters, make
sense. with this you can design feedback circuits, and calculate
stability, determine if the thing will oscillate, and what to do to
make it stop, FROM FIRST PRINCIPLES. You could calculate based on
fairly simple measurements, frequency and phase response of
transformers....Best of all, you can design from scratch, without
relying on a previous build, and have the pleasure of creating your
own solution to a problem that is thrown at you.
It's just another tool....
I had been building tube amps way back, starting in the '60's. At
that time I could design, but they were pretty crappy, and trial and
error was the only tool I had for design (other than replicating
someone elses stuff). Then, I had close to zero formal electronics
training. Some 40 years later, now as an engineer and instructor, I
can build up circuits using all the tools I've learned. Some of them
aren't much better than the ones I made from way back, but now I can
design to match the requirements of performance, cost, complexity,
safety, without going overboard on any one criteria.
Could I build up an audio transformer from scratch? ....no, I'd be
looking over your site real careful, and it would take me a few tries
before I got the necessary experience. I'm sure it would take me up to
a few hundred hours, and I'd expect you would take a similiar amount
of time to master AC electronics. The nice thing about the
transformers is that there's a lot of hands-on, whereas by yourself,
AC requires a lot of text reading.
And that brings me back to my experience as an instructor.... if
you want to "get" this stuff, you must have a lot of playing with
circuits before it makes sense. The trick as an instructor was to set
up a course so that "play" reinforced all the very basic concepts.
It's not that easy to do! Trying to show Kirchhoff's voltage laws,
Nyquist criteria, complex current made hands-on experiments a bit of a
challenge!
Our students with DC under their belt, and no basic math, no
previous experience (or love) of electronics would take 90-120 hrs to
master AC. I doubt you have any of those shortcomings, you could
probably pick it up pretty quickly. Whatever method you use to learn
this stuff, make sure it includes a LOT of hands-on stuff! Try to find
someone who LIKES this stuff to help you (in person).


....snip!....

If its too much trouble, I delete the damn thing, and
carry on as I have for years without it....

I like mucking around with amps or being out on my bicycle.

Sitting glued to the PC to perform in hours what i do
in 20 seconds in the workshop doesn't make my life easier.

The PC is a slave to me; I am not its slave.

Patrick Turner.

Hear, hear ! What you need is to have someone show you how to use
the damn thing, instead of going through countless documents. With
someone right there, and able to demonstrate how it works, you can cut
through endless hours of tedium. Find someone who knows well what
they're doing, and get 'em to show it to you in person. It will cut
the time enormously, and be a fun experience too.
Having to learn in a vaccuum is a really tough thing to do.

-Paul

[Andre Jute[_2_]]

On May 23, 3:30*pm, "Doug Bannard" wrote:
"Patrick Turner" wrote in message

...





John Byrns wrote:

In article ,
*Patrick Turner wrote:

Iain Churches wrote:

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches.../ImpedanceCalc...
or.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a
comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. *Also, I have a feeling
that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

What you are saying in the introduction now looks better, but technical
mumbo jumbo
nobody here understands is still there to confuse.

What "mumbo jumbo" are you talking about? *I haven't read the entire
page carefully enough to say that I have proofread it, but it looks
straight forward and easy enough to understand to me. *The math is quite
simple and is not rocket science.

Reactive network math is anything but easily understandable.

Iain has....

"The voltage is constant and the current is the sum of the vectors."

Nobody I know ever works out vectors. Nobody I know has a clue....
I don't, as a result, and its because I don't have to.

"The impedance Z of the network can be calculated by (R x
Xc)/(R^2+Xc^2)^0,5"

This is written to appear confusing to 99% of any beginner.

"The phase angle of the impedance is given by: Theta = arctan (Xc/R)
=-90+DEGREES(ATAN(Xc/R))"

Another completely incomprehensible formula that nobody uses, or can
understand.

What ppl CAN understand is simpler.

You always must have a SIMPLE REAL WORLD MODEL and application of a
circuit before understanding is at all possible
or useful.

1. So, there MUST be a broad bandwidth signal source, so assume a
voltage source with 0.0 ohms output resistance.

2. Assume this signal source does in fact have some source resistance,
so add a series R to represent it.

3. The output of the source resistance is the input to whatever network
you have.

4. The source resistance becomes part of the network whether you like it
or not
as the input terminal resistance and must be allowed for in
calculations.

5. There is an output terminal after the network from which a frequency
response is measured
always by a CRO probe or voltmeter such high input resistabce or
impedance that
the response of the network isn't affected.

6. There will be some real value of terminating resistance and or
reactance between output and 0V
after the network output.

7. The terminating impedance also becomes part of the network and
affects the way the network operates.

8. To establish what the response is of a network its teribly difficult
to calculate correctly
taking all the above into consideration.

9. Just build the damn network, knowing what the Rout of your sig gene
is, and measure it.

10. Adjust R&C values until you can plot the response you want.

11. Prove to yourself that only a guess can be made about real responses
easily.

12. Learn that hands on real world work in the darn workshop solves
problems.

13. And don't be afraid to simulate so that the risk of making a mistake
in a calculation is eliminated.

14. This leaves the possibility of making a mistake due to non inclusion
of some
factor.

15. Something is dead right when what you measure is exactly the same as
what you correctly calculate
and what you correctly simulate.

When a textbook is attempted to be written, the author does well to
assume his readers have low IQ,
and are insufferably dumb, and need everything all spelled out in easily
applicable layman's terms.

RDH4 is halfway there in many respects.

But many text books don't teach anything; they just confuse, and assume
the poor reader
has learnt it all elsewhere by miracle.

There are some of the concerns that should be in EVERYONE'S mind when
they have to build a network
to fiddle around with an amplifier response in any way.

Patrick Turner

My main complaint are the second and third sentences which introduce the
parallel RC network but then try their best to confuse us by presenting
an example of the application of a series RC network.

Regards,

John Byrns

--
Surf my web pages at, *http://fmamradios.com/

Well Iain, your spreadsheet works well for me and I think that you've done a
fine job subject to the changes that both Patrik and John Byrns have
suggested regarding defining your units.

As far as the remainder of Patrick's comments are concerned however, I'd
like to make a few of my own:

1) Reactive network math is really not at all difficult. *The key to
understanding it is to be able to draw the vector (actually called phasor)
diagram for the circuit under consideration. *If you find this difficult to
do, it is simply because you have not received the appropriate instruction
on the subject, and this is easily rectified. *There are many books
available, but IMHO, one of the better ones is entitled "Introduction to
Electric Circuits" by Herbert W Jackson. *This is still in print, is written
(unlike so many EE texts) to be easily understood, and is ideal for
self-study. *Another excellent book which should be bought at the same time
is "Electric Circuits" by Joseph A Edminister, also still in print I
believe. *This second book is a Schaum's Outline Series book and contains
hundreds of solved example problems.

2) Iain's spreadsheet is a very useful tool which allows you to evaluate
these networks without the need to resort to the math, and without having to
look up some "cookbook" formula to solve a problem. *Take advantage of it.

[Patrick Turner]

Doug Bannard wrote:

"Patrick Turner" wrote in message
...


John Byrns wrote:

In article ,
Patrick Turner wrote:

Iain Churches wrote:

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...edanceCalculat
or.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a
comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a feeling
that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

What you are saying in the introduction now looks better, but technical
mumbo jumbo
nobody here understands is still there to confuse.

What "mumbo jumbo" are you talking about? I haven't read the entire
page carefully enough to say that I have proofread it, but it looks
straight forward and easy enough to understand to me. The math is quite
simple and is not rocket science.

Reactive network math is anything but easily understandable.

Iain has....

"The voltage is constant and the current is the sum of the vectors."

Nobody I know ever works out vectors. Nobody I know has a clue....
I don't, as a result, and its because I don't have to.


"The impedance Z of the network can be calculated by (R x
Xc)/(R^2+Xc^2)^0,5"

This is written to appear confusing to 99% of any beginner.

"The phase angle of the impedance is given by: Theta = arctan (Xc/R)
=-90+DEGREES(ATAN(Xc/R))"

Another completely incomprehensible formula that nobody uses, or can
understand.

What ppl CAN understand is simpler.

You always must have a SIMPLE REAL WORLD MODEL and application of a
circuit before understanding is at all possible
or useful.

1. So, there MUST be a broad bandwidth signal source, so assume a
voltage source with 0.0 ohms output resistance.

2. Assume this signal source does in fact have some source resistance,
so add a series R to represent it.

3. The output of the source resistance is the input to whatever network
you have.

4. The source resistance becomes part of the network whether you like it
or not
as the input terminal resistance and must be allowed for in
calculations.

5. There is an output terminal after the network from which a frequency
response is measured
always by a CRO probe or voltmeter such high input resistabce or
impedance that
the response of the network isn't affected.

6. There will be some real value of terminating resistance and or
reactance between output and 0V
after the network output.

7. The terminating impedance also becomes part of the network and
affects the way the network operates.

8. To establish what the response is of a network its teribly difficult
to calculate correctly
taking all the above into consideration.

9. Just build the damn network, knowing what the Rout of your sig gene
is, and measure it.

10. Adjust R&C values until you can plot the response you want.

11. Prove to yourself that only a guess can be made about real responses
easily.

12. Learn that hands on real world work in the darn workshop solves
problems.

13. And don't be afraid to simulate so that the risk of making a mistake
in a calculation is eliminated.

14. This leaves the possibility of making a mistake due to non inclusion
of some
factor.

15. Something is dead right when what you measure is exactly the same as
what you correctly calculate
and what you correctly simulate.

When a textbook is attempted to be written, the author does well to
assume his readers have low IQ,
and are insufferably dumb, and need everything all spelled out in easily
applicable layman's terms.

RDH4 is halfway there in many respects.

But many text books don't teach anything; they just confuse, and assume
the poor reader
has learnt it all elsewhere by miracle.


There are some of the concerns that should be in EVERYONE'S mind when
they have to build a network
to fiddle around with an amplifier response in any way.

Patrick Turner


My main complaint are the second and third sentences which introduce the
parallel RC network but then try their best to confuse us by presenting
an example of the application of a series RC network.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

Well Iain, your spreadsheet works well for me and I think that you've done a
fine job subject to the changes that both Patrik and John Byrns have
suggested regarding defining your units.

As far as the remainder of Patrick's comments are concerned however, I'd
like to make a few of my own:

1) Reactive network math is really not at all difficult.

Oh yes it IS.

I don't know ANYONE with any clue how to calculate networks.

They all get stumped on 'j' and square root of -1, and other utterly
incomprehensible.

They use simulation programs maybe, or my seat of pants method.

understanding it is to be able to draw the vector (actually called phasor)
diagram for the circuit under consideration. If you find this difficult to
do, it is simply because you have not received the appropriate instruction
on the subject, and this is easily rectified.

I found RDH4 and a few other books quite incomprehensible.
I don't have funds or time for university.

I do have time to make very accurate RIAA networks using my simple
hands on approach.

There are many books
available, but IMHO, one of the better ones is entitled "Introduction to
Electric Circuits" by Herbert W Jackson. This is still in print, is written
(unlike so many EE texts) to be easily understood, and is ideal for
self-study. Another excellent book which should be bought at the same time
is "Electric Circuits" by Joseph A Edminister, also still in print I
believe. This second book is a Schaum's Outline Series book and contains
hundreds of solved example problems.

Maybe I read all the wrong books.

Luckily my work does not ever need me to be able to draw
vector diagrams or work through long equations with so many
pitfals for making a mistake.



2) Iain's spreadsheet is a very useful tool which allows you to evaluate
these networks without the need to resort to the math, and without having to
look up some "cookbook" formula to solve a problem. Take advantage of it.

All he had to do was present the impedance values at F for series and
parallel R&C.

What people do with this very easily calculated impedance at any F
even without an automatic spreadsheet and what the circuit function
outcome is
depends on a high standard of knowledge and practical experience.


The use of tools like spreadsheets on your PC should actually speed up your
calculations, minimize the chances of errors, and free you up to spend more
time in your shop!

But the Z of series or parallel RC is only the easy part.

Integrating the R&C and allowing for other surrounding R&C and Ra and
maybe some L et all is the hard part.

Patrick Turner.



Regards: Doug Bannard

[Iain Churches[_2_]]

"John Byrns" wrote in message
...
In article ,
"Iain Churches" wrote:

http://www.kolumbus.fi/iain.churches...ImpedanceCalcu
I have now made some changes. I would be grateful if you would
take another look John, and tell me if, in your opinion, the opening
sentences are now clearer.

They haven't changed as far as I can see. What I object to are the
following two sentences, "Let's start with the parallel combination. A
common example seeen often in schematics is the series RC combination in
parallel with the anode (plate) resistor on the first stage." It starts
talking about "the parallel combination", then cites as an example "the
series RC combination", then shows the diagram of a "RC Parallel
Network" before going into the discussion of parallel RC networks. What
I find confusing is the example given of a series RC network in the
middle of the discussion of parallel RC networks. A better example to
cite at that point would be that of a parallel RC network used as a low
frequency gain stepping network.

The phrase which starts: "Let's start with the parallel combination...."
is followed by a diagram of the parallel network. Beneath the diagram
are five sentences pertaining to the parallel case. Then comes a horizontal
separator.

After that comes the drawing for the series network, which is so labelled.
This is followed by five lines of text, and another horizontal line as a
separator
before the screen shot of the spreadsheet itself.

I have changed the weight of the separator to 3pt and the colour to dark
blue. Please have another look, John. I appreciate your comments.

You also present the following formula:
"Theta = arctan (Xc/R) =-90+DEGREES(ATAN(Xc/R))"
This formula is wrong on the face of it as the second equality sign
equates two quantities that are obviously not equal by inspection. This
equation essentially makes the claim that 0 = 90.


IIRC the first part of the equation, "Theta = arctan (Xc/R)" is correct
for the phase angle of an impedance, but the rest is not correct.

The formula was checked and also works in the spreadsheet (you will
find it in column I) perhaps you missed the minus symbol (-) after the
second equals symbol (=)


By the way I found one slight bug in your spread sheet. When I entered
Zero for the resistance value, the spread sheet blew up with errors.

I don't regard that as a bug:-)
One would have to be pretty obtuse to enter a zero
value in a combination to be calculated.

Thanks for your comments, John.

Best regards
Iain

[Iain Churches[_2_]]

"Patrick Turner" wrote in message
...


Iain Churches wrote:
You don't seem to be able to run Excel.

I don't have a clue if I can or not.

My PC is a 2003 model with standard domestic Windows XP.

Does it have Microsoft Office or Open Office installed?
Without the programmes the spreadsheet cannot run. Just as
you can't play a vinyl disc if you haven't got a turntable.

I do not want to have to pay for a special program ability to calculate
RC network Z values, because the formulas I have are from old books and
my brain combined with a
pocket calculator does very well thank you.

How long does it take you to calculate the Z of a CR network at
every F between 10Hz and 100kHz, and then draw the result on
log graph paper. The spreadsheet can do it faster than you can press
Enter select the tab and then Print.

That's what I did and the PC went through motions of instalation
and saving in my audio technical folder in a newly created file for it.

I open up the downloaded file and the window displayed as it should
have, but
It wasn't active. Just as useful as a dead cat.

Hmm. No one else seems to have had any trouble. Do you
have Microsoft Office or Open Office installed?

If its too much trouble, I delete the damn thing, and
carry on as I have for years without it....

That's a rather a Luddite attitude, but I agree with you.
I still use a bench signal generator and dedicated instruments
for test rather than any PC based software with narrow
bandwidth.

I like mucking around with amps or being out on my bicycle.

Sitting glued to the PC to perform in hours what i do
in 20 seconds in the workshop doesn't make my life easier.

Once again. The whole idea of the spreadsheet was to
give very fast printable results, that can be kept for
reference or compared.

The PC is a slave to me; I am not its slave.

Thats just as it should be:-)

Regards
Iain

[Iain Churches[_2_]]

"Patrick Turner" wrote in message
...


John Byrns wrote:

In article ,
Patrick Turner wrote:

Iain Churches wrote:

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...edanceCalculat
or.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a
comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a feeling
that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

What you are saying in the introduction now looks better, but technical
mumbo jumbo
nobody here understands is still there to confuse.

What "mumbo jumbo" are you talking about? I haven't read the entire
page carefully enough to say that I have proofread it, but it looks
straight forward and easy enough to understand to me. The math is quite
simple and is not rocket science.

Reactive network math is anything but easily understandable.

Iain has....

"The voltage is constant and the current is the sum of the vectors."


Morning Patrick. Please correct me if the above statement is not true.

Nobody I know ever works out vectors. Nobody I know has a clue....
I don't, as a result, and its because I don't have to.

You don't need to. The spreadsheet does all the work for you.
But it is important to convey the idea that the value of a CR
combination cannot be calculated as if it were a pair of resistors.

"The impedance Z of the network can be calculated by (R x
Xc)/(R^2+Xc^2)^0,5"


This is written to appear confusing to 99% of any beginner.

This is precisely the notation that Excel uses.
As I mentioned earlier, the page is probably not very useful
to beginners anyway:-) I notice also, that there seem to be
no beginners any more asking interesting questions on RAT.
They seem to have been driven away:-(


"The phase angle of the impedance is given by: Theta = arctan (Xc/R)
=-90+DEGREES(ATAN(Xc/R))"

Another completely incomprehensible formula that nobody uses, or can
understand.

Again, this is the Excel notation. Anyone familiar with spreadsheets
will recognise it. It's a tool, a means to an end, you do not need to
know the details of how it works to use it, in the same way as one does
not need to understand the workings of the internbal combustion engine
to drive a car. If one did, the roads would be pretty empty:-)

What ppl CAN understand is simpler.

You always must have a SIMPLE REAL WORLD MODEL and application of a
circuit before understanding is at all possible
or useful.

1. So, there MUST be a broad bandwidth signal source, so assume a
voltage source with 0.0 ohms output resistance.

2. Assume this signal source does in fact have some source resistance,
so add a series R to represent it.

3. The output of the source resistance is the input to whatever network
you have.

4. The source resistance becomes part of the network whether you like it
or not
as the input terminal resistance and must be allowed for in
calculations.

5. There is an output terminal after the network from which a frequency
response is measured
always by a CRO probe or voltmeter such high input resistabce or
impedance that
the response of the network isn't affected.

6. There will be some real value of terminating resistance and or
reactance between output and 0V
after the network output.

7. The terminating impedance also becomes part of the network and
affects the way the network operates.

8. To establish what the response is of a network its teribly difficult
to calculate correctly
taking all the above into consideration.

9. Just build the damn network, knowing what the Rout of your sig gene
is, and measure it.

10. Adjust R&C values until you can plot the response you want.

11. Prove to yourself that only a guess can be made about real responses
easily.

12. Learn that hands on real world work in the darn workshop solves
problems.

13. And don't be afraid to simulate so that the risk of making a mistake
in a calculation is eliminated.

14. This leaves the possibility of making a mistake due to non inclusion
of some
factor.

15. Something is dead right when what you measure is exactly the same as
what you correctly calculate
and what you correctly simulate.

All agreed. But further simplification does not have the slightest effect
on the use of the sheet. You just plug in two values and Excel does the
rest. You can then see the impedance of any series or parallel combination
at any F between 10Hz and 100kHz. This of course does not dispense
with the need for "final fettling" to get the precise values required in a
particular circuit.


I take your point about the source impedance and the impedance
which the network feeds. I would like to have the option to include
these in the calculations. Any ideas, Patrick.

When a textbook is attempted to be written, the author does well to
assume his readers have low IQ,
and are insufferably dumb, and need everything all spelled out in easily
applicable layman's terms.

RDH4 is halfway there in many respects.

RDH4 is far to complex for most hobbyists. That's why Morgan
Jones' books are so popular, they are written from a practical as
opposed to a theoretical point of view. He gives just enough theory
for the reader to understand the principle being discussed.

But thanks, Patrick for your comments. I will, when time permits
add diagrems to show the phase differences in the networks, if
that will make things a little clearer.

Best regards
Iain

[Patrick Turner]

Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:
You don't seem to be able to run Excel.

I don't have a clue if I can or not.

My PC is a 2003 model with standard domestic Windows XP.

Does it have Microsoft Office or Open Office installed?
Without the programmes the spreadsheet cannot run. Just as
you can't play a vinyl disc if you haven't got a turntable.


I did a search on the PC for Windows Excel and Microsoft Office, and
no files with those names are on the PC.

No wonder the spread sheet appeared like a dead cat.



I do not want to have to pay for a special program ability to calculate
RC network Z values, because the formulas I have are from old books and
my brain combined with a
pocket calculator does very well thank you.

How long does it take you to calculate the Z of a CR network at
every F between 10Hz and 100kHz, and then draw the result on
log graph paper. The spreadsheet can do it faster than you can press
Enter select the tab and then Print.

Sure, but only for the series of parallel network.

There isn't any allowance to add in a whole circuit.

I measure and graph a typical amp response in an exercize book
with pencil and in 5 minutes.

I have to measure REAL performances.

If I do have to actually know the Z value for the series or parallel RC
I just work it out, but mostly I don't have to know the Z value
right across a band, mainly just where XC = R.

I know what happens to the Z RC above and below the F where XC = R.

Knowing what I know is enough.
I get splendid results with the networks I use.




That's what I did and the PC went through motions of instalation
and saving in my audio technical folder in a newly created file for it.

I open up the downloaded file and the window displayed as it should
have, but
It wasn't active. Just as useful as a dead cat.

Hmm. No one else seems to have had any trouble. Do you
have Microsoft Office or Open Office installed?

No.

If its too much trouble, I delete the damn thing, and
carry on as I have for years without it....

That's a rather a Luddite attitude, but I agree with you.
I still use a bench signal generator and dedicated instruments
for test rather than any PC based software with narrow
bandwidth.

I like mucking around with amps or being out on my bicycle.

Sitting glued to the PC to perform in hours what i do
in 20 seconds in the workshop doesn't make my life easier.

Once again. The whole idea of the spreadsheet was to
give very fast printable results, that can be kept for
reference or compared.

The PC is a slave to me; I am not its slave.

Thats just as it should be:-)

I try to minimize the screenization of my lifestyle.

Patrick Turner.

Regards
Iain

[Patrick Turner]

Iain Churches wrote:

"Patrick Turner" wrote in message
...


John Byrns wrote:

In article ,
Patrick Turner wrote:

Iain Churches wrote:

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...edanceCalculat
or.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a
comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a feeling
that
he did not actually download the spreadsheet to view and print some
graphs (I seem to remember him saying that he does not have or use
Excel)

What you are saying in the introduction now looks better, but technical
mumbo jumbo
nobody here understands is still there to confuse.

What "mumbo jumbo" are you talking about? I haven't read the entire
page carefully enough to say that I have proofread it, but it looks
straight forward and easy enough to understand to me. The math is quite
simple and is not rocket science.

Reactive network math is anything but easily understandable.

Iain has....

"The voltage is constant and the current is the sum of the vectors."

Morning Patrick. Please correct me if the above statement is not true.

Nobody I know ever works out vectors. Nobody I know has a clue....
I don't, as a result, and its because I don't have to.

You don't need to. The spreadsheet does all the work for you.
But it is important to convey the idea that the value of a CR
combination cannot be calculated as if it were a pair of resistors.

"The impedance Z of the network can be calculated by (R x
Xc)/(R^2+Xc^2)^0,5"


This is written to appear confusing to 99% of any beginner.

This is precisely the notation that Excel uses.
As I mentioned earlier, the page is probably not very useful
to beginners anyway:-) I notice also, that there seem to be
no beginners any more asking interesting questions on RAT.
They seem to have been driven away:-(


People learning a new trade during middle age don't **** around
learning anything that doesn't become useful or reliable.

They just learn enough as they need to.

That's what I have done.

I ain't got the time to learn the incomprehensible mathematics
and vector digramming. There is simply no need.




"The phase angle of the impedance is given by: Theta = arctan (Xc/R)
=-90+DEGREES(ATAN(Xc/R))"

Another completely incomprehensible formula that nobody uses, or can
understand.

Again, this is the Excel notation. Anyone familiar with spreadsheets
will recognise it. It's a tool, a means to an end, you do not need to
know the details of how it works to use it, in the same way as one does
not need to understand the workings of the internbal combustion engine
to drive a car. If one did, the roads would be pretty empty:-)

What ppl CAN understand is simpler.

You always must have a SIMPLE REAL WORLD MODEL and application of a
circuit before understanding is at all possible
or useful.

1. So, there MUST be a broad bandwidth signal source, so assume a
voltage source with 0.0 ohms output resistance.

2. Assume this signal source does in fact have some source resistance,
so add a series R to represent it.

3. The output of the source resistance is the input to whatever network
you have.

4. The source resistance becomes part of the network whether you like it
or not
as the input terminal resistance and must be allowed for in
calculations.

5. There is an output terminal after the network from which a frequency
response is measured
always by a CRO probe or voltmeter such high input resistabce or
impedance that
the response of the network isn't affected.

6. There will be some real value of terminating resistance and or
reactance between output and 0V
after the network output.

7. The terminating impedance also becomes part of the network and
affects the way the network operates.

8. To establish what the response is of a network its teribly difficult
to calculate correctly
taking all the above into consideration.

9. Just build the damn network, knowing what the Rout of your sig gene
is, and measure it.

10. Adjust R&C values until you can plot the response you want.

11. Prove to yourself that only a guess can be made about real responses
easily.

12. Learn that hands on real world work in the darn workshop solves
problems.

13. And don't be afraid to simulate so that the risk of making a mistake
in a calculation is eliminated.

14. This leaves the possibility of making a mistake due to non inclusion
of some
factor.

15. Something is dead right when what you measure is exactly the same as
what you correctly calculate
and what you correctly simulate.

All agreed. But further simplification does not have the slightest effect
on the use of the sheet. You just plug in two values and Excel does the
rest. You can then see the impedance of any series or parallel combination
at any F between 10Hz and 100kHz. This of course does not dispense
with the need for "final fettling" to get the precise values required in a
particular circuit.

I take your point about the source impedance and the impedance
which the network feeds. I would like to have the option to include
these in the calculations. Any ideas, Patrick.


I'll leave you to think just how you want the thing you are doing to
appear, and what to include, but for me the only
approach worth considering for the PC is the wholistic one,
where whole circuit is spelled out for a simulation
program to work on and quantify and give a response
which could be printed.

In the case of the RIAA network, the wholistic approach
is the one I use to get the effectice values of resistances
involved; there are sources on the Net to hel calculate
values at least OK enough to begin with.

Then you have to trim, trim, and trim again
until you get the response you want to measure.

So I have never ever used a simulation program or ever seen a need to
use one.

My brain and a few simple formulas get me across the line well enough.



When a textbook is attempted to be written, the author does well to
assume his readers have low IQ,
and are insufferably dumb, and need everything all spelled out in easily
applicable layman's terms.

RDH4 is halfway there in many respects.

RDH4 is far to complex for most hobbyists. That's why Morgan
Jones' books are so popular, they are written from a practical as
opposed to a theoretical point of view. He gives just enough theory
for the reader to understand the principle being discussed.

Morgan isn't as good on many things as RDH4.

He leaves a hell of a lot to be desired.

But thanks, Patrick for your comments. I will, when time permits
add diagrems to show the phase differences in the networks, if
that will make things a little clearer.

Network programs can be purchased I think.

Good ones allow for full LCR theory.

I get by without all this stuff.

Patrick Turner.

Best regards
Iain

[Iain Churches[_2_]]

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:
You don't seem to be able to run Excel.

I don't have a clue if I can or not.

My PC is a 2003 model with standard domestic Windows XP.

Does it have Microsoft Office or Open Office installed?
Without the programmes the spreadsheet cannot run. Just as
you can't play a vinyl disc if you haven't got a turntable.


I did a search on the PC for Windows Excel and Microsoft Office, and
no files with those names are on the PC.

No wonder the spread sheet appeared like a dead cat.

That would seem to be the reason. Just like a vinyl pressing without
a turntable:-)



I do not want to have to pay for a special program ability to calculate
RC network Z values, because the formulas I have are from old books and
my brain combined with a
pocket calculator does very well thank you.

How long does it take you to calculate the Z of a CR network at
every F between 10Hz and 100kHz, and then draw the result on
log graph paper. The spreadsheet can do it faster than you can press
Enter select the tab and then Print.

Sure, but only for the series of parallel network.

There isn't any allowance to add in a whole circuit.

Perhaps it would be an interesting option to add the source and
the load components. Can you suggest how this can be done?

Regards
Iain

[Iain Churches[_2_]]

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:
You don't seem to be able to run Excel.

I don't have a clue if I can or not.

My PC is a 2003 model with standard domestic Windows XP.

Does it have Microsoft Office or Open Office installed?
Without the programmes the spreadsheet cannot run. Just as
you can't play a vinyl disc if you haven't got a turntable.


I did a search on the PC for Windows Excel and Microsoft Office, and
no files with those names are on the PC.

No wonder the spread sheet appeared like a dead cat.

You should be able to find them if youy click "Start" bottom left,
and then "All programs"


I do not want to have to pay for a special program ability to calculate
RC network Z values, because the formulas I have are from old books and
my brain combined with a
pocket calculator does very well thank you.

How long does it take you to calculate the Z of a CR network at
every F between 10Hz and 100kHz, and then draw the result on
log graph paper. The spreadsheet can do it faster than you can press
Enter select the tab and then Print.

Sure, but only for the series of parallel network.

There isn't any allowance to add in a whole circuit.

Perhaps it would be an interesting option to add the source and
the load components. Can you suggest how this can be done?

Regards
Iain

[Patrick Turner]

Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:
You don't seem to be able to run Excel.

I don't have a clue if I can or not.

My PC is a 2003 model with standard domestic Windows XP.

Does it have Microsoft Office or Open Office installed?
Without the programmes the spreadsheet cannot run. Just as
you can't play a vinyl disc if you haven't got a turntable.


I did a search on the PC for Windows Excel and Microsoft Office, and
no files with those names are on the PC.

No wonder the spread sheet appeared like a dead cat.

That would seem to be the reason. Just like a vinyl pressing without
a turntable:-)



I do not want to have to pay for a special program ability to calculate
RC network Z values, because the formulas I have are from old books and
my brain combined with a
pocket calculator does very well thank you.

How long does it take you to calculate the Z of a CR network at
every F between 10Hz and 100kHz, and then draw the result on
log graph paper. The spreadsheet can do it faster than you can press
Enter select the tab and then Print.

Sure, but only for the series of parallel network.

There isn't any allowance to add in a whole circuit.

Perhaps it would be an interesting option to add the source and
the load components. Can you suggest how this can be done?

You don't do anything yourself.

Just by a good full CAD program with full LCR networking and it'll be
better than anything
you'll ever have time for.

The wheel has already been invented....

Patrick Turner.

Regards
Iain

[Patrick Turner]

Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:
You don't seem to be able to run Excel.

I don't have a clue if I can or not.

My PC is a 2003 model with standard domestic Windows XP.

Does it have Microsoft Office or Open Office installed?
Without the programmes the spreadsheet cannot run. Just as
you can't play a vinyl disc if you haven't got a turntable.


I did a search on the PC for Windows Excel and Microsoft Office, and
no files with those names are on the PC.

No wonder the spread sheet appeared like a dead cat.

You should be able to find them if youy click "Start" bottom left,
and then "All programs"

Yeah, well, Microsoft Office is lsted in the list of my programs.

Searching for it said it wasn't there.

Patrick Turner.

[Iain Churches[_2_]]

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:
You don't seem to be able to run Excel.

I don't have a clue if I can or not.

My PC is a 2003 model with standard domestic Windows XP.

Does it have Microsoft Office or Open Office installed?
Without the programmes the spreadsheet cannot run. Just as
you can't play a vinyl disc if you haven't got a turntable.


I did a search on the PC for Windows Excel and Microsoft Office, and
no files with those names are on the PC.

No wonder the spread sheet appeared like a dead cat.

You should be able to find them if youy click "Start" bottom left,
and then "All programs"

Yeah, well, Microsoft Office is lsted in the list of my programs.

Searching for it said it wasn't there.


And the fact that the spreadsheet didn't run,
is probably confirmation of that.

But just to be sure, click Start, then All Programs.
You should see a list of programs including
Microsoft Office. Hold the cursor over
this to open a pull-down list which should
include Excel.

Regards
Iain

[John Byrns]

In article ,
"Iain Churches" wrote:

"John Byrns" wrote in message
...
In article ,
"Iain Churches" wrote:

http://www.kolumbus.fi/iain.churches...ts/ImpedanceCa
lcu
I have now made some changes. I would be grateful if you would
take another look John, and tell me if, in your opinion, the opening
sentences are now clearer.

They haven't changed as far as I can see. What I object to are the
following two sentences, "Let's start with the parallel combination. A
common example seeen often in schematics is the series RC combination in
parallel with the anode (plate) resistor on the first stage." It starts
talking about "the parallel combination", then cites as an example "the
series RC combination", then shows the diagram of a "RC Parallel
Network" before going into the discussion of parallel RC networks. What
I find confusing is the example given of a series RC network in the
middle of the discussion of parallel RC networks. A better example to
cite at that point would be that of a parallel RC network used as a low
frequency gain stepping network.

The phrase which starts: "Let's start with the parallel combination...."
is followed by a diagram of the parallel network. Beneath the diagram
are five sentences pertaining to the parallel case. Then comes a horizontal
separator.

After that comes the drawing for the series network, which is so labelled.
This is followed by five lines of text, and another horizontal line as a
separator
before the screen shot of the spreadsheet itself.

I have changed the weight of the separator to 3pt and the colour to dark
blue. Please have another look, John. I appreciate your comments.

Either my browser is retrieving an old version of your page, or you
aren't following what I am saying. What I am objecting to is the
mention of a series RC as an example when you are discussing the
parallel RC. In the parallel RC discussion you say "A common example
seeen often in schematics*is the series RC combination in parallel with
the anode (plate) resistor on the first stage." This is not an example
of a simple parallel RC network, it is an example of a series RC network
in parallel with the plate resistor, a more complex combination that you
haven't yet addressed.

You also present the following formula:
"Theta = arctan (Xc/R) =-90+DEGREES(ATAN(Xc/R))"
This formula is wrong on the face of it as the second equality sign
equates two quantities that are obviously not equal by inspection. This
equation essentially makes the claim that 0 = 90.

IIRC the first part of the equation, "Theta = arctan (Xc/R)" is correct
for the phase angle of an impedance, but the rest is not correct.

The formula was checked and also works in the spreadsheet (you will
find it in column I) perhaps you missed the minus symbol (-) after the
second equals symbol (=)

I thought you would see where I was going without my being too explicit,
the point is that "Theta = arctan (Xc/R) =-90+DEGREES(ATAN(Xc/R))" is
incorrect as it stands.

"Theta = arctan (Xc/R) is correct for the series RC combination.
and
"Theta =-90+DEGREES(ATAN(Xc/R))" is correct for the parallel RC
combination, but that doesn't make them equivalent as your equation with
two equal signs implies.

By the way I found one slight bug in your spread sheet. When I entered
Zero for the resistance value, the spread sheet blew up with errors.

I don't regard that as a bug:-)
One would have to be pretty obtuse to enter a zero
value in a combination to be calculated.

I am pretty obtuse. Setting C = 0.0 uF is even worse than setting R = 0
Ohms. It is easy enough to change the formulas to fix most of the
problems, although a conditional test would be needed for the Xc formula
to show symbol for infinity when c = 0.0 uF.

Also what do you intend the "capacitive reactance Xc" to represent in
the parallel case? I would expect Xc to be the capacitive reactance to
represent the equivalent series reactance part of the parallel
combination, but that isn't what you calculate. Your intention here is
both unconventional, and quite obtuse.

Further your column headings for the two "dB" columns are misleading and
wrong in some of their implications, I would change the column headings
to more correctly reflect the quantity you are actually calculating.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Iain Churches[_2_]]

"John Byrns" wrote in message
...
In article ,
"Iain Churches" wrote:

"John Byrns" wrote in message
...
In article ,
"Iain Churches" wrote:

http://www.kolumbus.fi/iain.churches...ts/ImpedanceCa

Either my browser is retrieving an old version of your page, or you
aren't following what I am saying. What I am objecting to is the
mention of a series RC as an example when you are discussing the
parallel RC. In the parallel RC discussion you say "A common example
seeen often in schematics is the series RC combination in parallel with
the anode (plate) resistor on the first stage." This is not an example
of a simple parallel RC network, it is an example of a series RC network
in parallel with the plate resistor, a more complex combination that you
haven't yet addressed.

This is now changed


I thought you would see where I was going without my being too explicit,
the point is that "Theta = arctan (Xc/R) =-90+DEGREES(ATAN(Xc/R))" is
incorrect as it stands.

The second " =" should have been "Or for the parallel case"
This too is changed.

By the way I found one slight bug in your spread sheet. When I entered
Zero for the resistance value, the spread sheet blew up with errors.

I don't regard that as a bug:-)
One would have to be pretty obtuse to enter a zero
value in a combination to be calculated.

I am pretty obtuse.

:-))

Setting C = 0.0 uF is even worse than setting R = 0
Ohms. It is easy enough to change the formulas to fix most of the
problems, although a conditional test would be needed for the Xc formula
to show symbol for infinity when c = 0.0 uF.

No one using the spreadsheet in a practical application will
set either value to zero. Neither will they try to use negative quantities.

Also what do you intend the "capacitive reactance Xc" to represent in
the parallel case? I would expect Xc to be the capacitive reactance to
represent the equivalent series reactance part of the parallel
combination, but that isn't what you calculate. Your intention here is
both unconventional, and quite obtuse.

What do you mean by "the equivalent series reactance part
of the parallel combination"?

Xc in both cases is simply the reactance of the cap at the frequency
Hence the values E10 and M10 are the same. This is true right down
to E46 and M46.

Further your column headings for the two "dB" columns are misleading and
wrong in some of their implications, I would change the column headings
to more correctly reflect the quantity you are actually calculating.

No-one I have asked can suggest a better heading. Do you have a
suggestion?

Thanks for your comments.

Iain

[Patrick Turner]

Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:
You don't seem to be able to run Excel.

I don't have a clue if I can or not.

My PC is a 2003 model with standard domestic Windows XP.

Does it have Microsoft Office or Open Office installed?
Without the programmes the spreadsheet cannot run. Just as
you can't play a vinyl disc if you haven't got a turntable.


I did a search on the PC for Windows Excel and Microsoft Office, and
no files with those names are on the PC.

No wonder the spread sheet appeared like a dead cat.

You should be able to find them if youy click "Start" bottom left,
and then "All programs"

Yeah, well, Microsoft Office is lsted in the list of my programs.

Searching for it said it wasn't there.


And the fact that the spreadsheet didn't run,
is probably confirmation of that.

But just to be sure, click Start, then All Programs.
You should see a list of programs including
Microsoft Office. Hold the cursor over
this to open a pull-down list which should
include Excel.

Yes, I have Microsoft Office Excel 2003.

It appears to start, so I will try saving your program, and
opening it in Excel.

It now works. You didn't tell me that to enter new R&C values etc at the
top of the sheet
after you have clicked on the item you want to change.

Patrick Turner.



Regards
Iain

[Iain Churches[_2_]]

"Patrick Turner" wrote in message
...

Yes, I have Microsoft Office Excel 2003.

It appears to start, so I will try saving your program, and
opening it in Excel.

It now works. You didn't tell me that to enter new R&C values etc at the
top of the sheet
after you have clicked on the item you want to change.


At the top of the sheet itself are two broad green arrows, and
the request to enter values into the cells G3 ande G4.

Below the lo-res screen shot of the spreadsheet, it states:
The value of C (the capacitor) is entered in µF in cell G3.
The value of R (the resistor) is entered in cell G4. These
are the only two entries required to see the impedance (Z)
of the parallel or series combination.

Glad you have got it working:-) I am grateful for the
comments from members of RAT.

Regards
Iain

[Doug Bannard]

"Patrick Turner" wrote in message
...


Doug Bannard wrote:

"Patrick Turner" wrote in message
...


John Byrns wrote:

In article ,
Patrick Turner wrote:

Iain Churches wrote:

"Ian Thompson-Bell" wrote in message
...
Iain Churches wrote:
There has been some discussion on RAT recently
about amplifier stability and RC networks.

Most of us find the values for these by empirical methods,
using a rule-of-thumb or two and a couple of decade boxes.

I thought it might be useful to have these values calculated
from 10Hz to 100kHz in an Excel spreadsheet which would
also plot the impedance, Z, the phase, and the dB changes
for both parallel and series combinations.

http://www.kolumbus.fi/iain.churches...edanceCalculat
or.html

It is still under development. Please have a look, and
download the spreadsheet (Excel 2003 or later) to put it
through its paces.

Any (constructive) comments will be greatly appreciated.

Just a couple of comments as Patrick seems to have done a
comprehensive
job as usual.

Yes. I was grateful for his comments although it was not obvious
to him what was the intention of this page. Also, I have a
feeling
that
he did not actually download the spreadsheet to view and print
some
graphs (I seem to remember him saying that he does not have or use
Excel)

What you are saying in the introduction now looks better, but
technical
mumbo jumbo
nobody here understands is still there to confuse.

What "mumbo jumbo" are you talking about? I haven't read the entire
page carefully enough to say that I have proofread it, but it looks
straight forward and easy enough to understand to me. The math is
quite
simple and is not rocket science.

Reactive network math is anything but easily understandable.

Iain has....

"The voltage is constant and the current is the sum of the vectors."

Nobody I know ever works out vectors. Nobody I know has a clue....
I don't, as a result, and its because I don't have to.


"The impedance Z of the network can be calculated by (R x
Xc)/(R^2+Xc^2)^0,5"

This is written to appear confusing to 99% of any beginner.

"The phase angle of the impedance is given by: Theta = arctan (Xc/R)
=-90+DEGREES(ATAN(Xc/R))"

Another completely incomprehensible formula that nobody uses, or can
understand.

What ppl CAN understand is simpler.

You always must have a SIMPLE REAL WORLD MODEL and application of a
circuit before understanding is at all possible
or useful.

1. So, there MUST be a broad bandwidth signal source, so assume a
voltage source with 0.0 ohms output resistance.

2. Assume this signal source does in fact have some source resistance,
so add a series R to represent it.

3. The output of the source resistance is the input to whatever network
you have.

4. The source resistance becomes part of the network whether you like
it
or not
as the input terminal resistance and must be allowed for in
calculations.

5. There is an output terminal after the network from which a frequency
response is measured
always by a CRO probe or voltmeter such high input resistabce or
impedance that
the response of the network isn't affected.

6. There will be some real value of terminating resistance and or
reactance between output and 0V
after the network output.

7. The terminating impedance also becomes part of the network and
affects the way the network operates.

8. To establish what the response is of a network its teribly difficult
to calculate correctly
taking all the above into consideration.

9. Just build the damn network, knowing what the Rout of your sig gene
is, and measure it.

10. Adjust R&C values until you can plot the response you want.

11. Prove to yourself that only a guess can be made about real
responses
easily.

12. Learn that hands on real world work in the darn workshop solves
problems.

13. And don't be afraid to simulate so that the risk of making a
mistake
in a calculation is eliminated.

14. This leaves the possibility of making a mistake due to non
inclusion
of some
factor.

15. Something is dead right when what you measure is exactly the same
as
what you correctly calculate
and what you correctly simulate.

When a textbook is attempted to be written, the author does well to
assume his readers have low IQ,
and are insufferably dumb, and need everything all spelled out in
easily
applicable layman's terms.

RDH4 is halfway there in many respects.

But many text books don't teach anything; they just confuse, and assume
the poor reader
has learnt it all elsewhere by miracle.


There are some of the concerns that should be in EVERYONE'S mind when
they have to build a network
to fiddle around with an amplifier response in any way.

Patrick Turner


My main complaint are the second and third sentences which introduce
the
parallel RC network but then try their best to confuse us by
presenting
an example of the application of a series RC network.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

Well Iain, your spreadsheet works well for me and I think that you've
done a
fine job subject to the changes that both Patrik and John Byrns have
suggested regarding defining your units.

As far as the remainder of Patrick's comments are concerned however, I'd
like to make a few of my own:

1) Reactive network math is really not at all difficult.

Oh yes it IS.

I don't know ANYONE with any clue how to calculate networks.

They all get stumped on 'j' and square root of -1, and other utterly
incomprehensible.

They use simulation programs maybe, or my seat of pants method.

understanding it is to be able to draw the vector (actually called
phasor)
diagram for the circuit under consideration. If you find this difficult
to
do, it is simply because you have not received the appropriate
instruction
on the subject, and this is easily rectified.

I found RDH4 and a few other books quite incomprehensible.
I don't have funds or time for university.

I do have time to make very accurate RIAA networks using my simple
hands on approach.

There are many books
available, but IMHO, one of the better ones is entitled "Introduction to
Electric Circuits" by Herbert W Jackson. This is still in print, is
written
(unlike so many EE texts) to be easily understood, and is ideal for
self-study. Another excellent book which should be bought at the same
time
is "Electric Circuits" by Joseph A Edminister, also still in print I
believe. This second book is a Schaum's Outline Series book and contains
hundreds of solved example problems.

Maybe I read all the wrong books.

Luckily my work does not ever need me to be able to draw
vector diagrams or work through long equations with so many
pitfals for making a mistake.



2) Iain's spreadsheet is a very useful tool which allows you to evaluate
these networks without the need to resort to the math, and without having
to
look up some "cookbook" formula to solve a problem. Take advantage of
it.

All he had to do was present the impedance values at F for series and
parallel R&C.

What people do with this very easily calculated impedance at any F
even without an automatic spreadsheet and what the circuit function
outcome is
depends on a high standard of knowledge and practical experience.


The use of tools like spreadsheets on your PC should actually speed up
your
calculations, minimize the chances of errors, and free you up to spend
more
time in your shop!

But the Z of series or parallel RC is only the easy part.

Integrating the R&C and allowing for other surrounding R&C and Ra and
maybe some L et all is the hard part.

Patrick Turner.



Regards: Doug Bannard

Well Patrick, I guess that we'll just have to agree to disagree about the
difficulty of the math involved. I'm no math lover, but I don't find it too
onerous...and I too am one of these guys who spends a lot of time building
and testing stuff on the bench.
Contrary to poular belief, I do not own a pair of pajamas with phasor
diagrams, Bode plots, Nyquist plots or even inverse Laplace transforms on
them (but I'd sure like to).

Best Regards : Doug Bannard