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--- In LTspice@..., John Woodgate wrote:

A constructive, serious answer! Thank you.

[Y]ou have initially to forget all you know about the product,
program or application and consider ONLY what questions the
user is likely to ask.

This much I already supposed, but the reemphasis is appreciated.

Looking back at the original poster's difficulty in processing
this sentence from Help,

"A model card is required to define the behavior of the switch.",

which to me clearly indicates that the user must create a model
statement in which he assigns values to the switch parameters.
Also implied is that this model statement is usually created in
the form of a SPICE text directive and placed upon the schematic.
A complete novice probably wouldn't know this without an example
or pouring over the manual (which I did when I was brand new to
LTspice, by the way).

Also the sentence refers to a model card, which is most likely a
meaningless term to those who weren't around in the days of punch
card input (I wish Mike would expunge that term from any and all
non-historical documentation). Still, these shortcomings would
be overcome and answered by an example, a link to which Help *did*
provide in this case.

For each question, you then 'switch on' ONLY that part of your
product knowledge needed to answer the question. If you feel
compelled to add more, formulate another question to introduce
the addition.

This is really good advice, as it would tend to overcome the
problems from reading comprehension and information overload that
were mentioned earlier. I wonder if this technique can be done
in a way that is compatible with Help remaining an efficient
reference manual. Anyway, thanks for the idea.

Hundreds of questions are likely to be required. The limited
lists of up to 20 or so, offered by Microsoft and other Helps,
are pitifully inadequate.

True, but a well done wiki could offer unlimited possibilities,
both in links and graphics.

Answers should include examples wherever possible.

Well, in the switch example, Help offered,

"See the schematic file .\examples\Educational\Vswitch.asc to see
an example of a model card placed directly on a schematic as a
SPICE directive.",

which the original poster seemed not to have read (or at least
ignored, hence my legitimate question about the possibility of
there being either a reading comprehension problem or laziness at
play). Note that this example would have answered any lingering
questions about what "a model card" could mean.

Regards -- analogspiceman

In message <075FBDBF-7FC5-4AE8-921F-42D73C76DF0D@...>, dated Fri, 16 Sep 2011, Jim Wagner <wagnerj@...> writes:

As a further example, there is not a single screen snapshot in the whole documentation.

I found several. 'Adding attributes', 'Adding the pins' and 'Attached cursors', for example, all include graphics if not exactly screen-shots. 'Colour palette editor' is another.

It just says "do this... " or "do that...". For MANY people, that is simply not sufficient. That is not the way that many people learn.

Agreed; it's not always the best way to communicate.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
When I point to a star, please look at the star, not my finger. The star will
be more interesting.

In message <744FF547-789E-48F5-9AE6-A4FF04DCCB25@...>, dated Fri, 16 Sep 2011, Jim Wagner <wagnerj@...> writes:

As far as I can see, "constructive criticism" does no good. The documentation appears to be the sole perview of Mike and it will be what he wants it to be.

Mike obviously has a responsibility to ensure that the Help is completely accurate. But to extend that to saying that no improvement will be entertained is not justified.

End of story.

By no means.

I have offered several positive suggestions about documentation improvement, including the "go check PSpice documentation, its mostly the same" and put what needs to be put into single document. That was shot down by you and others. So, what else is one to do?

Simply don't accept the 'shoot down'. You can write, if you choose, your own 'Jim's Guide to LTspice' and put it on your web site or even in the Files or Files -> Tut folders on the list's web site.

I would be delighted to contribute to the Wiki, but its not clear how. The front page of the Wiki says "create an account to contribute" but there is no link or information about creating an "account".

If so, it needs to be fixed.

Clearly,j genuine input is not wanted.

Now, that is NOT a constructive criticism. I hope this message will de-frustrate you, at least a bit.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
When I point to a star, please look at the star, not my finger. The star will
be more interesting.

On Sep 16, 2011, at 11:12 AM, John Woodgate wrote:

In message <j500ob+lpdp@...>, dated Fri, 16 Sep 2011,
analogspiceman <analogspiceman@...> writes:

Well, people keeping complaining about Help, but so far no one,
including the complainers, has been willing or able to offer any
concrete constructive criticism. It remains a puzzle. -- a.s.

It needs a complete re-write, but the necessary combination of
skills is
extremely rare - a way to put over intricate concepts in simple
language
AND a deep understanding of LTspice. I have had some success in the
first, but I am nowhere in the second.

To do the first, you have initially to forget all you know about the
product, program or application and consider ONLY what questions the
user is likely to ask. For each question, you then 'switch on' ONLY
that
part of your product knowledge needed to answer the question. If you
feel compelled to add more, formulate another question to introduce
the
addition.

Hundreds of questions are likely to be required. The limited lists
of up
to 20 or so, offered by Microsoft and other Helps, are pitifully
inadequate. Answers should include examples wherever possible.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
When I point to a star, please look at the star, not my finger. The
star will
be more interesting.

As a further example, there is not a single screen snapshot in the
whole documentation. It just says "do this... " or "do that...". For
MANY people, that is simply not sufficient. That is not the way that
many people learn.

Another example: the documentation has few REAL examples. Step-by-
step, picture-by-picture, of how you add a model, or a sub-circuit.
Again, words are fine, words are necessary, but words are not
sufficient.

Jim Wagner
Oregon Research Electronics

[Non-text portions of this message have been removed]

On Sep 16, 2011, at 10:24 AM, analogspiceman wrote:

--- In LTspice@..., John Woodgate wrote:

--- In LTspice@..., analogspiceman wrote:

How to make Help continue to function as a compact and efficient
reference while also being able to effectively provide answers
that neophytes can actually see, process and put to use?

This is, in my experience, a problem with ALL Helps. I could write
a 3-screen post but I won't.

Well, people keeping complaining about Help, but so far no one,
including the complainers, has been willing or able to offer any
concrete constructive criticism. It remains a puzzle. -- a.s.

As far as I can see, "constructive criticism" does no good. The
documentation appears to be the sole perview of Mike and it will be
what he wants it to be.

End of story.

I have offered several positive suggestions about documentation
improvement, including the "go check PSpice documentation, its mostly
the same" and put what needs to be put into single document. That was
shot down by you and others. So, what else is one to do?

I would be delighted to contribute to the Wiki, but its not clear how.
The front page of the Wiki says "create an account to contribute" but
there is no link or information about creating an "account".

Clearly,j genuine input is not wanted.

Jim Wagner
Oregon Research Electronics

[Non-text portions of this message have been removed]

In message <j500ob+lpdp@...>, dated Fri, 16 Sep 2011, analogspiceman <analogspiceman@...> writes:

Well, people keeping complaining about Help, but so far no one, including the complainers, has been willing or able to offer any concrete constructive criticism. It remains a puzzle. -- a.s.

It needs a complete re-write, but the necessary combination of skills is extremely rare - a way to put over intricate concepts in simple language AND a deep understanding of LTspice. I have had some success in the first, but I am nowhere in the second.

To do the first, you have initially to forget all you know about the product, program or application and consider ONLY what questions the user is likely to ask. For each question, you then 'switch on' ONLY that part of your product knowledge needed to answer the question. If you feel compelled to add more, formulate another question to introduce the addition.

Hundreds of questions are likely to be required. The limited lists of up to 20 or so, offered by Microsoft and other Helps, are pitifully inadequate. Answers should include examples wherever possible.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
When I point to a star, please look at the star, not my finger. The star will
be more interesting.

Agree whole-heartedly, Helmut.

--- In LTspice@..., John Woodgate wrote:

--- In LTspice@..., analogspiceman wrote:

How to make Help continue to function as a compact and efficient
reference while also being able to effectively provide answers
that neophytes can actually see, process and put to use?

This is, in my experience, a problem with ALL Helps. I could write
a 3-screen post but I won't.

Well, people keeping complaining about Help, but so far no one,
including the complainers, has been willing or able to offer any
concrete constructive criticism. It remains a puzzle. -- a.s.

--- In LTspice@..., Tony "ttakeshian" wrote:

I need to model the coupling coefficient of two inductors as
a function of time. I tried using combination of .func and
.param statements to pass a time varying variable to the
SPICE K component without success.

As you have noted, K must be a fixed value. However, LTspice
includes a behavioral inductor that may be a function of time.
I suppose you could set up a T-network of three such inductors
to vary with time the percentage of inductance shared between
each side of the "T" while keeping the total inductance "seen"
from each side fixed (this is what K effectively does). If
you require other than a one-to-one turns ration, you could
add an ideal transformer to one side of the T. -- a.s.

PS: The behavioral inductor is well described in Help and in the
many examples available here in the group archive, both in past
messages and in files posted.

In message <j4vu3g+ano2@...>, dated Fri, 16 Sep 2011, analogspiceman <analogspiceman@...> writes:

How to make Help continue to function as a compact and efficient reference while also being able to effectively provide answers that neophytes can actually see, process and put to use?

This is, in my experience, a problem with ALL Helps. I could write a 3-screen post but I won't. It's a good PhD project on communication for someone.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
When I point to a star, please look at the star, not my finger. The star will
be more interesting.

An emphatic yes. In one of my courses, Network Synthesis, one learns that for minimum phase networks (no zeros in the right half plane), the phase response of the network can be determined from the magnitude frequency response. As to A.S.'s remarks, I do not believe you have a physically realizable circuit by replacing a Laplace transform by its magnitude response. Complex poles and zeros need to occur in pairs in order for the time function to be a real valued function -- and to have a physically realizable circuit.

Hubert

--- In LTspice@..., Helmut Sennewald wrote:

We shouldn't attack users when we don't know about their
knowledge and capabilities. Please keep that in mind.

Hello Helmut,

I think you have mistakenly interpreted my response as an attack
when it was not. In fact, a reading or comprehension problem was
one of several reasonable possibilities to ask about, given that
the original poster claimed to have read the Help topic on the
switch element, yet was unable to see that it clearly stated the
he must provide a model statement.

This section of the Help topic is very short and includes a clear
link to an example schematic, something that would have answered
his questions. Yet for some reason, he did not run the example.
I truly would like to know the reason why not (and why so many
other people seem to have trouble with Help). This really is a
puzzle to me.

I am gradually coming to the conclusion that written words, even
if short and simple, are not always "seen." It may be because
the reader is not a native speaker of English, it may be because
they are faced with an information overload, or it may be that
the "Twitter" generation can't always effectively process
traditional "dry" textbook-style information (i.e., a reading
comprehension problem), or it may be simple laziness (which, I
suppose a person has the right to be - as long as they don't try
to steal the labor of others).

Anyway, I wonder if Help would be more effective if it included
graphical examples or at least hot links to graphical examples
or hotlinks to launch example schematics. The question remains:

How to make Help continue to function as a compact and efficient
reference while also being able to effectively provide answers
that neophytes can actually see, process and put to use?

Regards -- analogspiceman

In message <4E736E3F.4040008@...>, dated Fri, 16 Sep 2011, Bhakakhan <bhakakhan@...> writes:

Indeed, we should attack users, who attack users - it seems that this is the only language, those pseudo-masters will understand.

Johannes Herrmann / Yahoo Micbuilders Group

P.S. In our group, such an incident is unthinkable. that'll be worth a strike.

On the other hand, is a 'me too' post to a moderator's post in any way helpful? Isn't it liable to make things worse?
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
When I point to a star, please look at the star, not my finger. The star will
be more interesting.

I need to model the coupling coefficient of two inductors as a function of time. I tried using combination of .func and .param statements to pass a time varying variable to the spice K component without success. I also have tried the trick used for defining a time varying resistor using a voltage of a node in the schematic.

Any suggestion would be greatly appreciated.

tony

I think a distinction needs to be made between attacking the issue and
attacking the user..
Cheers
AG

Indeed, we should attack users, who attack users - it seems that this
is the only language, those pseudo-masters will understand.

Johannes Herrmann / Yahoo Micbuilders Group

P.S. In our group, such an incident is unthinkable. that'll be worth a
strike.

best regards...

The "Pick New Transistor" function is wonderful, allowing me to sort by key features for an easy selection of the available library of parts. Is there any way to access a selector menu like this for the wide selection of LT opamps? I really want to use LT opamps in my current design, but I'm getting tired of going up to the LT site and using their feature selection tool to find an appropriate opamp. If I think I need an amplifier with a faster slew rate to solve my immediate problem, it would be nice to get into the LTspice opamp selection menu, sort by slew rate, then select a device that has the proper range of features. I often find myself running simulations in places where I don't have access to the LT website, so this feature would be really nice to have. Is it already there and I just don't know about it?

--- In LTspice@..., "analogspiceman" <analogspiceman@...> wrote:

--- In LTspice@..., Michael Stuarts wrote:

The model for SW appears to missing. If anyone can help me
create a .model statement for schematic that would be great.
I could not figure out how to do it from the help file alone.

Why not? Do you have a reading comprehension problem?

Hello analogspiceman and all others,

We shouldn't attack users when we don't know about their
knowledge and capabilities. Please keep that in mind.

Best regards,
Helmut
Moderator

PS:
Especially using the switch sw is often the first time
where a new user has to define a model.

Tony

You should have taken the hint by now that my query on modelling frequency dependence was done in total oblivion of Shivesh's original thread over which for some reason you keen wanting to remind me about. Shivesh's several specfiic replies have been infinitely more helpful and constructive...

George

_____

From: Tony Casey [mailto:tony@...]
To: LTspice@...
Sent: Fri, 16 Sep 2011 12:08:42 +0100
Subject: [LTspice] Re: Freqeucny Dependent resistor






<snip>
--- In LTspice@..., "George Evans" <george.evans@...> wrote:

Guys all this is first year circuit theory. We all know and come across series to paarllel convertions of reactive networks that introduce FDR effects where the real part of the immitance function varies with freq and these are LINEAR circuits. And as no real device is devoid of inductive/capacitive parasitics ,no matter how small, freq dependancy should not be a mistery.

Nonlinear effects were the reason I started this thread for modeling such things as ferrite cores. Manufactures rountinely supply spice parameters for these devices which involve freq dependant effects related to nonlinear loss mechanisms ( hysterisis etc ) .
George

</snip>
George,

It's no more trivial than referring to the help file to find the correct syntax for using Laplace in dependent sources, which was the subject of your original question in this thread, which as far as I can determine, was actually started by Shivesh.

Regards,
Tony








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--- In LTspice@..., "Tony Casey" <tony@...> wrote:

<snip>

However some transient simulations take 20-30 minutes to run, and when you reload the plot settings, it gets rid of the cursors. Plus every 5-10 seconds, the plot re-autoscales as more results are added to it. I am having a fighting battle. I have also considered using min/max, but I like the scales I've chosen with 55V on the left and 550A on the right, and I'm not sure I'd get them to match as nicely.

I really want to rant, and I'm sure I want to connect someone to the output of the power supply, but to be honest, I am so thankful for LT Spice that I can only manage "Thank you Mike" :)

</snip>
Hello Alan,

Part of your problem can be sorted by disabling marching waves, either from the Simulation menu, or by adding:
.option nomarch
in the schematic. This speeds up long .tran simulations considerably.

Regards,
Tony

I mean the "View>Marching Waves" menu.