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Hi RainbowSally!

Wow, you weren't kidding. OMIGOD, you should have seen the circuit I came up with while you were redoing the first one...somehow I got the notion in my head I needed to use peak detecting op amp circuits to define the top and bottom of the sawtooth, so I had both positive and negative peak detectors feeding a potentiometer going to a comparator....

....your circuit was a marvel of sophisticated elegance, I can't thank you enough.

I would post my new version of your re-do, but...I'm still waiting for LTspice to find an operating point LOL!!!

I'm going to bed now. If, in the morning, it gave an error (time-step error most likely; I think that's when it can't converge?), I'll post it asking for help getting it to run, and we can talk about design at the same time.

However, if it does finally run, then I have no reason to post it here; it would be off-topic to discuss the design elements (I've added a new section you haven't seen yet that's the point of the 1st circuit) - so am wondering where you'd like to continue the discussion...electronics_101? funwithtransistors? (both yahoo groups).

Very Best, with gratitude for your help, Maturin..errr, Gandolf LOL

Hi Helmut,

please accept my apologies; it was the end of a hard day with some unexpected blows, and I got into complaint mode (never a good idea)...and came off like a mixture of a jerk and idiot (take your pick). I promise to never complain about LTspice again (no matter how frustrated I get LOL).

Fact is, it's a gift worth its weight in diamonds, and I'm grateful to have both a spice with a very user-friendly interface and a yahoo group LTspice moderator who has displayed extraordinary patience and helpfulness for years...wow.

I'll see if I can recreate that node problem with the TI model, and if I can, post it here; maybe it'll be helpful to find out why some outside models/symbols are problematic to use. In the meantime, I'll take the suggestion of another poster to use the universal op amp model and change parameters as needed; GREAT idea, much thanks.

VB, Maturin

Andy,

The Gmail IDs can be used to login into Yahoo, the Group settings allows for using a Gmail or a Yahoo email address as the primary one. My ID, now, is the Gmail one, and I can browse, reply, upload/download files.
What's confusing about Shigematsu-san is that he can login, post, view files, but not download them. Which is really strange, indeed.

Shigematsu-san, you said that you made another account and you could login and make changes, as well. You also said you want to change/modify your Yahoo ID. Combining these two togehter, why not delete that Yahoo account and then make another one the way you wanted? Or just use the newly created ones.


Vlad

Also, I have saved the .asc file in database for your reference which i have been using/trying to modify :flyback_nom.asc

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

Hello

You may want to try the other Yahoo group, "switchmode", they may have the answers you're looking for.


Good luck,
Vlad

Hi,
i was thinking that the main component what i have used is of LT and so this group should be aiding me.

Thanks
Yoga

--- In LTspice@..., Andy <Andrew.Ingraham@...> wrote:

Getting back to the original question again ... (Is there a tool to
convert a SPICE model to a schematic?) ...

Two data points so far are:

- It might cost you $100K.

and

- None of them work well for Analog circuits.

I'd like to suggest that it might not be quite as bad as this. I
believe there are cheaper alternatives available. I ran across one a
while back (costing only around a thousand bucks?) that claims to be
able to do it. I am also led to believe that some academic research
work *might* be available for free, if you know where to find it.

As for quality, let's just say "your mileage may vary." Might be
acceptable, might be horrible, depending on the quality of the
program, and on the circuit you feed into it.

So I don't want to give you unrealistic hope ... but I also don't want
you to be so discouraged to believe that it is impossible either. As
I said earlier, converting to a schematic is NOT a trivial problem.
So far, this is one of those tasks that the human brain is much better
than a computer at doing well.

Regards,
Andy

Re: Netlist to LTspice schematic

As far as I know LTspice does not support a schematics to schematics conversion program, SO even if you love the schematics that you get by netlist conversion with whatever tool, you will not be able to move these schematics into LTspice automatically.

There is a common Electronics Design tool Interchange Format called (EDIF) which will allow EDIF to be used as an intermediate format however I've never heard of an EDIF=>LTspice schematics. I believe that the schematics tool on which LTspice schematics is based is now part of the "Laker" design tools package, unfortunately it underwent a major rewrite some years back so it is probably no longer compatible with LTspice (I know one of the changes was to make the schematic .asc file into a binary format).


BTW EDIF transfer hardly ever works properly because each schematic system has it's own quirks and preference for symbol size / drawing grid etc. not to mention funny constructs such as component loops (as supported in LTspice). These funny constructs do not have generic EDIF equivalents, so we re-enter by hand!

PPS: It is not by accident that no two design entry tools are really completely inter-operable. The big players like the tool Lock-In they get with incompatibility. Just to show you how cynical the industry is many tool vendors support and EDIF reader but hardly any supply an EDIF writer.

Hello again Shiggy-san,

I have already tryed the Yahoo ID asuming as mr.shigematsu@... and
mr.shigematsu.

But those are not Yahoo IDs!

"mr.shigematsu@..." is your Gmail address. "mr.shigematsu" is
your Gmail username. Both of them are for Gmail; they are not for
Yahoo.

Q1) Would you tell me the method of ascertain the yahoo ID.

Your Yahoo ID is what you picked when you originally signed up for
your Yahoo account. If you have a Yahoo email address, then you have
a Yahoo ID which is the part of the Yahoo email address before the "@"
symbol.

For example, if you have the email address "mr1.shigematsu@...",
then "mr1.shigematsu" would be the Yahoo ID for that email address.

But you might have more than one Yahoo ID (and I think you do). You
should use the same Yahoo ID that you used when you became a member of
the [LTspice] group. That is the Yahoo ID that gives you access to
the [LTspice] files.

I have tried it according to their instruction, I could not modify
it.(failure).
So I have already asked to Yahoo about modifing my profile(Yahoo ID and my
name).

I think it is not possible to modify a Yahoo ID. The Yahoo ID itself
is fixed and probably cannot be changed.

I hope I do not offend you, but I think most of the problems you are
having, are because of your understanding of English. It may be best
if you ask for help from a friend who knows English better than you
do.

Best regards,
Andy

Getting back to the original question again ... (Is there a tool to
convert a SPICE model to a schematic?) ...

Two data points so far are:

- It might cost you $100K.

and

- None of them work well for Analog circuits.

I'd like to suggest that it might not be quite as bad as this. I
believe there are cheaper alternatives available. I ran across one a
while back (costing only around a thousand bucks?) that claims to be
able to do it. I am also led to believe that some academic research
work *might* be available for free, if you know where to find it.

As for quality, let's just say "your mileage may vary." Might be
acceptable, might be horrible, depending on the quality of the
program, and on the circuit you feed into it.

So I don't want to give you unrealistic hope ... but I also don't want
you to be so discouraged to believe that it is impossible either. As
I said earlier, converting to a schematic is NOT a trivial problem.
So far, this is one of those tasks that the human brain is much better
than a computer at doing well.

Regards,
Andy

But there aren't many models or even internal schematics on the
internet.

On the contrary, there are thousands upon thousands of SPICE models on
the Internet!

Part of the difficulty is determining which ones are worthy of using
and which ones are not. For a popular IC component like a 741 or a
555, you could probably find literally hundreds if not thousands of
copies of SPICE models for them on the 'net, of which a few dozen are
distinct from one another; and then your job is to choose which one(s)
to run with.

Internal schematics, now there you may be correct that they are hard
to find on the Internet. It used to be (when an op-amp was about as
complex an IC as you could get) that equivalent schematics were often
included on the data sheet for the part. Of course the schematic
didn't show you the characteristics of the transistors and diodes, and
maybe omitted resistor values too, but at least it was a starting
point.

And I have seen and used a number of vendor-supplied SPICE models that
included schematics in the documentation that accompanied those
models.

Regards,
Andy

I wrote:

I think you misunderstood. The macro-model contains FAKE elements
that stand in for whole sections of transistors and stuff.

rainbowsally replied:

Understood. But they can be recreated using discretes. This truly
isn't a problem.

I hope I am neither offending, nor coming off sounding like a jerk ...
but I am still not sure you understand.

Let's say someone hands you a SPICE model for an IC, part number XYZ,
which you want to use in your circuit, and simulate in LTspice.

But being the curious type, you need to know what is in that model.
You want to see it visually in schematic form. So you spring for that
$100K conversion program which converts it into a schematic. And,
voila, it spits out a schematic consisting of:
a couple of voltage sources,
a few resistors and capacitors,
and a behavioral controlled source described by an equation.
Not a transistor in sight! In other words, it is one of those dreaded
"macro-models" that represents the behavior (rather than the
structure) of the XYZ part.

Sure, you could replace it or recreate it using discretes ... if you
knew what discretes to use! But you don't. All you have is the
macro-model. You know nothing else about the insides of this XYZ
part.

For that TLC555 that started this discussion, if the SPICE model you
have is one of these macro-models, then you might have no way to
understand why the input current is the same as it was for an old
NE555, even though the TLC555 is supposed to be a CMOS part.

Furthermore, it truly is a problem when the macro-model does not
accurately represent a certain behavior of the device that matters to
you. And that can easily happen.

Andy

Hi Andy-san!

Thanks your clear email.

How do you believe that it is blocked?

---> Blocked means bellow meanings.
1) The system blocked positively by any reason.
2) My profile information was modified by any reason which include my
operation.
-------------------------------------------------------------------------------------------------
This is my intuition which judged the surrounding situation synthetically.
------------------------------------------------------------------------------------------------

I have already tryed the Yahoo ID asuming as mr.shigematsu@... and
mr.shigematsu.
But I could not access the File of LTspice.

Q1) Would you tell me the method of ascertain the yahoo ID.

I have tried it according to their instruction, I could not modify
it.(failure).
So I have already asked to Yahoo about modifing my profile(Yahoo ID and my
name).
But I have not get the answer from them at present.

Shiggy



2012/8/30 Andy <Andrew.Ingraham@...>

**


Hi Shiggy-san,


You wrote:

My old email address (mr.shigematsu@...) is blocked in yahoo

system,

I think.
But I do not know the method of unblock.

How do you believe that it is blocked?

Yahoo has many components, including Yahoo email, Yahoo groups (like
this one), and others. My Gmail email address is not related to
Yahoo. I do not use that email address to access or download the
[LTspice] files. It seems like you were trying to use your email
address to try to download the [LTspice] files, but I don't understand
why you would do that.

But there is a Username (Yahoo calls it a "Yahoo! ID") that you need
to use when you sign in to Yahoo, which you must do before you can see
and download the [LTspice] files. You can only use a Yahoo! ID to
sign in to Yahoo. You cannot use a Gmail username to login to Yahoo
(and you can't use a Yahoo! ID to login to Gmail).

The Yahoo! ID is usually just a name. Yours might be "mr1.shigematsu"
... but Yahoo also lets you type it as "mr1.shigematsu@...".
They are not really asking for your email address when you sign in;
they are looking for your Yahoo! ID.

Andy

Ok, I see where I have to get to next.

Thank you.

RobertTalty wrote:

:-)

Looks like I'll be creating and studying asy files and libs for a while.

Jim Thompson wrote:

I wish there was. I understand Cadence claims to have such a tool...
sets you back ~$100K>:-o

So, if you want to see, you have to grunt>:-}

On the other side of the argument, though, sometimes you don't care
to see the innards. I regularly import a customer's portion of a
chip into my design, simply by connecting their netlist up as a
subcircuit. Thus I can simulate the whole enchilada proving my additions.

- Jim Thompson

That's a bit advanced for me, but I'd like to get to the point where I can do that too.

Thank you! :-)

Andy wrote:
<snip>

Nope. Not a problem. Those can be replaced by actual transistors once
the connections are identified.

I think you misunderstood. The macro-model contains FAKE elements
that stand in for whole sections of transistors and stuff.

Understood. But they can be recreated using discretes. This truly isn't a problem.

<snip>

And making use of these macro-models, can create problems (these are
the "problems" I alluded to before). A simple VCVS used as a
macro-model does not clip. A real op-amp does.

Precisely. :-)

But there aren't many models or even internal schematics on the internet. So I thought I'd start... and after I did one xx339 comparator with some degree of success (from an image of the schematic).

Someone around here did the entire NE555 chip and that has been extremely useful to me. I'd like to do the same with a few opamps and stuff.

And no... not going to search old message in this forum. Yow!

Well then you are missing out on a TON of useful information! This
group has a decade's worth of experience in them thar' archives.

I'm not a very good reader. I can parse a schematic MUCH better than I can parse words, but if you give me some realistic search terms, I'd give it a whirl.

I don't think I'd want to wade through all the results for "subcircuit", for example because as you say, in "ten years" most of the hits are going to be non-useful and I have dialup which is prohibitively slow for this kind of thing even using Ctrl-F to locate possible hits.

But never mind, Andy.

I'll figure it out myself eventually. I was just hoping there was an easier way.

If your approach is to say, "Give me the answers now, I don't want to
see the answer to the same question you wrote last (week, year,
whatever)", then I'm not so sure I'd want to help. Hopefully you will
reconsider.

Currently spending all "searching" time using datasheetcatalogs.com to find data sheets and manufacturers that I like and mouser.com to look up the same parts to get pricing. Took several hours to find some good prospects for the power output stage for kevin's amp (4th hack with realistic parts).

I don't have time.

But I'm willing to share the methods and results with everyone here. Hope that's not a problem. ;-)

Do you ever use the Internet? Google? Wikipedia? So if you are
willing to find an answer to something on the Internet that was
written two years ago, why won't you do the same here in this forum?

Good luck with your project.

It's not my project. It's Kevin's. And it's Gandolf's. And it's going to blow the doors off and come in at 1/4th the price of a cookbook solution.

--- In LTspice@..., rainbowsally <rainbowsally@...> wrote:

I love the scematics (especially analogspiceman's.. :-) they are
beautiful. I can even read my own!

But I'd like to literally see how some of these subcircuits are modeled
so I can see why things behave as they do. For example I got TLC555
which I believe is a CMOS 555 timer (and they're cheap and giving 'em
away right now), but when I measure the input currents they are
identical to the old NE555 model we have in our lib folders somewhere.

So what I'm asking is this. How do I get a visual representation of the
components MINUS the *.asy file. And I don't care how many steps it
might take. Might even write a converter program if there isn't a way
to do this inside ltspice.

Drawing them component by component is on my don't-do list.

:-)

Over MANY years I've tried lots of netlist to Schematic conversion programs. To be honest none of them work well for Analog circuits.

For digital schematics the best I ever saw was from a company called Veiwlogic, but this company has long since faded from the scene. Many professional IC design packages include netlist to Schematic conversion because it is sometimes needed when you are debugging digital Logic that was auto generated from Verilog code.

Unfortunately the tool you are searching for does not exist, so save yourself time searching and learn to read Spice netlists and draw the schematic by hand, then reenter it into LTspice and compare the schematic's netlist with the original netlist. There are automatic tools for comparing netlists, typically I'd use the Layout Vs Schematic (LVS) comparison tool BUT enter two netlists instead of a Layout and schematic.

-Robert

Your are right, but i am looking toward extracting the results from a text
file which is directly obtained by executing scad3.exe from the command
window! I mean, I want to bypass the waveform window!

The netlist for a subcircuit is essentially a "directed graph" (not a Cartesian graph, nor radial graph like you drew in high school) See the "tutorial/GraphDrawing" in the Mathematica help.

Mathematica has plotting tools for "graphs" and "directed graphs". Any edge and any vertex can be given a name. Beyond that, Mathematica has built in the ability to use any Mathematica object for a node label or edge label (or more generally for any legend entry, plot point, etc.) and such functionality can be nested arbitrarily deep.

There are 7 precanned "Methods" for organizing the drawing. None of these are likely to pretty like analogspiceman pretty, but if you got lucky, one of the methods might provide an aha! perspective. The most obvious problem is that a human wants to see functionally related nodes clumped together and the functional information is generally not available in the LTSpice netlist.

Using BFI, you could look at your first attempt, and decide that it would be smart to assign each connection to node zero in the LTSpice subcircuit netlist to a separate vertex in the output graph and use a little image of a ground symbol for each of those vertices. Similarly for each node YOU judge to be worthy of being given a netlist name as opposed to a netlist number.

To fully automate the process you'd probably want to use LISP or Prolog and plan on spending the rest of your life writing code to run on a cluster.

I wish there was. I understand Cadence claims to have such a tool... sets you back ~$100K >:-o

So, if you want to see, you have to grunt >:-}

On the other side of the argument, though, sometimes you don't care to see the innards. I regularly import a customer's portion of a chip into my design, simply by connecting their netlist up as a subcircuit. Thus I can simulate the whole enchilada proving my additions.

- Jim Thompson

I wrote:

It is NOT trivial to convert a netlist of one form or another, into a
human-readable schematic.

rainbowsally wrote:

Not talking about a netlist.... I don't think. (???)

There are all kinds of netlists. A netlist is generically just a file
that has all the information about connectivity of your circuit.

Most people who inquire about converting a SPICE model to a schematic,
are starting with a subcircuit, which IS a SPICE netlist. It is a
text file that lists all the components as well as how they are
interconnected. I thought that was what you were starting with.

By the way, the *.asy file is just the symbol you see on your
schematic. It itself has NONE of the information about the schematic
it represents.

Many IC models are macro-models and contain functional equivalents for
whole blocks of circuitry. Some IC macro-models don't even contain a
single transistor! And that can give rise to various problems.

Nope. Not a problem. Those can be replaced by actual transistors once
the connections are identified.

I think you misunderstood. The macro-model contains FAKE elements
that stand in for whole sections of transistors and stuff.

Say you've got an IC op-amp. Someone can replace the whole op-amp
with a VCVS, which is just an E-element in SPICE. Doing so loses all
of the components that made up that IC! You would not be able to come
along later and restore the actual transistors to the schematic,
unless you (somehow) also had a schematic in your other hand for the
insides of the IC op-amp that was used.

So I'm saying the SPICE model you have for (say) that TLC555 you have,
*might* not even have any transistors in it! It might be just a
functional equivalent of a generic '555. (Hopefully not!)

And making use of these macro-models, can create problems (these are
the "problems" I alluded to before). A simple VCVS used as a
macro-model does not clip. A real op-amp does.

And no... not going to search old message in this forum. Yow!

Well then you are missing out on a TON of useful information! This
group has a decade's worth of experience in them thar' archives.

If your approach is to say, "Give me the answers now, I don't want to
see the answer to the same question you wrote last (week, year,
whatever)", then I'm not so sure I'd want to help. Hopefully you will
reconsider.

Do you ever use the Internet? Google? Wikipedia? So if you are
willing to find an answer to something on the Internet that was
written two years ago, why won't you do the same here in this forum?

Good luck with your project.

Andy

BTW, that wasn't really the problem with the url I posted. When I joined the copied url from the actual file (which contains the user's id and isn't the real path) and the path to the files area, I accidentally left an extra '//' in the path.

I'll be more careful in the future.

Andy wrote: