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In message <j4sde1+lkfq@...>, dated Thu, 15 Sep 2011, cukkacan <mustafa_cukka@...> writes:

Hey, i am sophomore at the university, and i have a circuit sketch and data sheet. However, i dont know how to use LT Spice effectively. i couldnt build the circuit on LT Spice perfectly. Could you help me about this issue ?

Study the examples and tutorials available on the list's web site. Read the Help. Upload your non-working schematic to the web site Files -> Temp and tell us you've done it.

Also, advices about Class D amp are welcome. i need a working class-d amp circuit about 10-20W.i have checked on the web, topics are not live.

This list is not a general design help list. A web search for 'Class D' will provide you with hundreds of good hits (and some bad ones, but you can't win them all).
--
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 LTspice@..., Mahmudul Kabir <nilonjana@...> wrote:

Dear Members,
?
Is there any chance to calculate of real or imaginary part
of impedance while doing a simulation?with any AC voltage?
?
Or is it possible to draw?a trace of real part or imaginary
part of impedace in LTspice?
?
Thank you in advance,
?
Mahmudul Kabir, Japan

Hello Mahmudul Kabir,

I assume you use .AC simulation. In this case you can plot
in Cartesian format which shows the real part with a solid
line and the imaginary part with a dashed line.

Best regards,
Helmut

--- In LTspice@..., "rug_rossi" <rrossi@...> wrote:

I need to add a noise generator to the model of a sensor
(simply a behavioral source), in order to perform some
noise analysis.

Noise is described by a noise density and a 1/f corner.

which is the best way to do that?
Add to my model a voltage follower made with the
Universal OP amp level 1, or there is a better way?

best regards,

Ruggero Rossi

Hello Ruggero,

The 1/f noise is implemented in diodes. Thus diode noise may be
the natural choice for an 1/f noise source.

Files > Tut > noisegen
Files > Tut > noisegen_with_subcircuits
Files > Tut > new_diode_noise.asc


You already mentioned the "universalopamp". It contains
parameters en and enk to set noise value and corner frequency.

Best regards,
Helmut

Dear Members,
?
Is there any chance to calculate of real or imaginary part of impedance while doing a simulation?with any AC voltage?
?
Or is it possible to draw?a trace of real part or imaginary part of impedace in LTspice?
?
Thank you in advance,
?
Mahmudul Kabir, Japan
?

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

--- In LTspice@..., "stm6823@..." <stevemorris@...> wrote:

When I try to run AD8336-2.asc in FILES&#92;AD8336 I get an error message that contains "Circuit: * C:&#92;Program Files&#92;LTC&#92;AD models&#92;AD8336&#92;AD8336-2.asc

WARNING: Node U1:U4_N24227 is floating."
But checking the .net file I do not find any NC.
Whats wrong?
Thanks in advance,
STM

Hello STM,

I have corrected your symbol and the schematic. It has been
also necessary to add some convergence help.
It has required the critical option

.options cshunt=1e-15

I have uploaded a working example.

Files > Temp > AD8336 > AD8336_1.zip.

Best regards,
Helmut

I need to add a noise generator to the model of a sensor (simply a behavioral source), in order to perform some noise analysis.

Noise is described by a noise density and a 1/f corner.

which is the best way to do that?
Add to my model a voltage follower made with the Universal OP amp level 1, or there is a better way?

best regards,

Ruggero Rossi

Hey, i am sophomore at the university, and i have a circuit sketch and data sheet. However, i dont know how to use LT Spice effectively. i couldnt build the circuit on LT Spice perfectly. Could you help me about this issue ?

Also, advices about Class D amp are welcome. i need a working class-d amp circuit about 10-20W.i have checked on the web, topics are not live.

--- In LTspice@..., "pindsen" <windven@...> wrote:

Hi,

I need an BSS138 in my LTSpice simulation.
Since I can't find that component in the program itself, I need to make it.

I have done the following steps but LTspice won't simulate:

1) Downloaded a Zetex BSS138 spice subcircuit and placed it in a "BSS138.sub" file
2) The spice file is placed in c:&#92;program files&#92;LTC&#92;LTspiceIV&#92;lib&#92;sub
3) Included a nmos symbol (nmos.asy) in the design
4) Renamed the symbol to BSS138/ZTX
5) Add a spice directive command ".inc BSS138.sub"
6) Hit the run button
7) LTspice can't simulate and says "Can't find definition of model "bss138".

The Zetex spice model can be seen here:

*ZETEX BSS138 Spice Mosfet Subcircuit Last revision 11/91
*
.SUBCKT BSS138/ZTX 3 4 5
* Nodes D G S
M1 3 2 5 5 MOD1
RG 4 2 343
RL 3 5 6E6
D1 5 3 DIODE1
.MODEL MOD1 NMOS VTO=1.109 RS=1.474 RD=1.59 IS=1E-15 KP=0.597
+CGSO=23.5P CGDO=4.5P CBD=53.5P PB=1 LAMBDA=267E-6
.MODEL DIODE1 D IS=1.254E-13 N=1.0207 RS=0.222
.ENDS

Can anyone help?

Best regards
Carsten Wind
Denmark

Hello Carsten,

4a)
Ctrl-right-mouse-click on the placed symbol nmos.
Change Prefix:MN to Prefix:X

2) I always recommend to save model files in the folder of the
schematic.

Best regards,
Helmut

Hi,

I need an BSS138 in my LTSpice simulation.
Since I can't find that component in the program itself, I need to make it.

I have done the following steps but LTspice won't simulate:

1) Downloaded a Zetex BSS138 spice subcircuit and placed it in a "BSS138.sub" file
2) The spice file is placed in c:&#92;program files&#92;LTC&#92;LTspiceIV&#92;lib&#92;sub
3) Included a nmos symbol (nmos.asy) in the design
4) Renamed the symbol to BSS138/ZTX
5) Add a spice directive command ".inc BSS138.sub"
6) Hit the run button
7) LTspice can't simulate and says "Can't find definition of model "bss138".

The Zetex spice model can be seen here:

*ZETEX BSS138 Spice Mosfet Subcircuit Last revision 11/91
*
.SUBCKT BSS138/ZTX 3 4 5
* Nodes D G S
M1 3 2 5 5 MOD1
RG 4 2 343
RL 3 5 6E6
D1 5 3 DIODE1
.MODEL MOD1 NMOS VTO=1.109 RS=1.474 RD=1.59 IS=1E-15 KP=0.597
+CGSO=23.5P CGDO=4.5P CBD=53.5P PB=1 LAMBDA=267E-6
.MODEL DIODE1 D IS=1.254E-13 N=1.0207 RS=0.222
.ENDS

Can anyone help?

Best regards
Carsten Wind
Denmark

Dear Sir,
Will you please tell us how to do it? There might be cases when it is not such a bad idea.
Best Regards
E.A.Neonakis

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

Incidentally, the registry hack method works for almost any kind of file association, and can usefully be employed to invoke the a native Linux PDF reader, for example, from within many Windows applications (running in wine) that can call PDF files, instead of using a Windows version installed in the same wine bottle.

Thanks for that, although I use the Linux version of the Adobe reader for viewing PDFs. and LTspice is now the only Windows app that I use on a regular basis.

However, I'd like to try it on .net, .cir and .log files - I don't like the appearance of Notepad (purely a personal thing) so I'll try setting up an association to use the native editor of my choice.

Cheers,

Martin

On Sep 14, 2011, at 10:24 PM, martin562284 wrote:

--- In LTspice@..., "analogspiceman"
<analogspiceman@...> > You can more or less do this now if you know
how, but it is a

really bad idea

Well, I wouldn't go so far as to say "really bad", just undesirable.
But that's precisely why I'd like to have the facility to have an
optional (with the emphasis on "optional") intermediate directory
hierarchy - something akin to the Windows/Linux $PATH environment
variable principle....

unless you are certain you will never need to share
your work with anyone else

As I'm a one-man band, sadly I very rarely have the need/opportunity
to share with others, but see below...

(including with yourself when you are
on another computer at a later date trying to go back and recreate
your now-forgotten wonder design).

I regularly (almost daily) move between two or three PCs and, with
the aid of Unison, have no problem in keeping all my stuff in sync.

I'm not so presumptuous as to consider my designs "wonderful", but
for the most part they work sufficiently well to meet my needs and I
have some simple but effective, tried and tested processes for
keeping track of them and the third-party models I use...

To share successfully, you will
have to hunt down all your custom components and symbols that you
have made to appear to *you* as just another part of standard
LTspice.

Keeping all user project files in a dedicated folder for each
project allows you to easily recognize and zip together all your
custom work for run-out-of-the-box sharing.

Most of my projects use non-standard (ie. not provided in the
standard LTspice release) models, subs or libs, not just of my own
design but also third-party models, libraries and subs. I don't want
to keep multiple copies of these in each project directory as it
gives me a version control headache. Anything which is project-
specific stays in the project directory.

It's the stuff that I use time and time again that I want to find a
home for, preferably separate from the LTspice lib directory, which
is what my suggestion is all about. This would apply to models, also
- at present LTspice has the facility to add third-party models into
the standard.* files (ref. scad3.pdf, p187, para 3c) - I believe it
would also be better to keep these separate.

Unless Mike were to
a "Ferret & Zip" tool that discretely bundled up all your dangling
custom bits with a single button click, this idea is better left
as an unfulfilled wish. -- a.s.

I neither expect nor need Mike to provide any such tool - I'm happy
to look after that for myself. It's actually quite simple. Due to
the elegance of LTspice's file formats, all the information is
readily available. I'd be more than willing to assist in producing
an "official" tool, should the opportunity arise.

I'm not demanding nor even requesting that you or anyone else change
your way of working, I'm just requesting a facility to give me, and
any one else who wishes it, the freedom to work in the way we
choose. In the meantime, I'm happy to share my experience with
others who wish to tread the same path.

I really do agree with Martin. The simple idea that one way fits all
is simply not productive. Many of us have different styles of file
management. The idea that our user environment must be exactly that
which facilitates sharing over the internet is constraining. And, it
is really at odds with the idea of giving the user many ways to hang
him or her self. If we need to share a design, then why not a "share
design" or "export" menu item that packages all of the needed files
together and zips them in an appropriate hierarchy of folders (and
adjusts directive-based model references)?

The inclusion of a "project file" that references all of the project
files would make file management quite straight forward. I am really
quite surprised that such a strategy has not been adopted. It need not
get in the way of using legacy netlists or model files. After all,
virtually every software development environment allows inclusion of
library files of all sorts. LTspice need not be any different!

Jim Wagner
Oregon Research Electronics

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

--- In LTspice@..., "analogspiceman" <analogspiceman@...> > You can more or less do this now if you know how, but it is a

really bad idea

Well, I wouldn't go so far as to say "really bad", just undesirable. But that's precisely why I'd like to have the facility to have an optional (with the emphasis on "optional") intermediate directory hierarchy - something akin to the Windows/Linux $PATH environment variable principle....

unless you are certain you will never need to share
your work with anyone else

As I'm a one-man band, sadly I very rarely have the need/opportunity to share with others, but see below...

(including with yourself when you are
on another computer at a later date trying to go back and recreate
your now-forgotten wonder design).

I regularly (almost daily) move between two or three PCs and, with the aid of Unison, have no problem in keeping all my stuff in sync.

I'm not so presumptuous as to consider my designs "wonderful", but for the most part they work sufficiently well to meet my needs and I have some simple but effective, tried and tested processes for keeping track of them and the third-party models I use...

To share successfully, you will
have to hunt down all your custom components and symbols that you
have made to appear to *you* as just another part of standard
LTspice.

Keeping all user project files in a dedicated folder for each
project allows you to easily recognize and zip together all your
custom work for run-out-of-the-box sharing.

Most of my projects use non-standard (ie. not provided in the standard LTspice release) models, subs or libs, not just of my own design but also third-party models, libraries and subs. I don't want to keep multiple copies of these in each project directory as it gives me a version control headache. Anything which is project-specific stays in the project directory.

It's the stuff that I use time and time again that I want to find a home for, preferably separate from the LTspice lib directory, which is what my suggestion is all about. This would apply to models, also - at present LTspice has the facility to add third-party models into the standard.* files (ref. scad3.pdf, p187, para 3c) - I believe it would also be better to keep these separate.

Unless Mike were to
a "Ferret & Zip" tool that discretely bundled up all your dangling
custom bits with a single button click, this idea is better left
as an unfulfilled wish. -- a.s.

I neither expect nor need Mike to provide any such tool - I'm happy to look after that for myself. It's actually quite simple. Due to the elegance of LTspice's file formats, all the information is readily available. I'd be more than willing to assist in producing an "official" tool, should the opportunity arise.

I'm not demanding nor even requesting that you or anyone else change your way of working, I'm just requesting a facility to give me, and any one else who wishes it, the freedom to work in the way we choose. In the meantime, I'm happy to share my experience with others who wish to tread the same path.

Thanks.. I usually count on only 40 db from differential stuff or 1%
matching.. 0.1% is achievable with a lot of attention to layout When I
get time I will read his postings in detail. It reinforces my thesis
that simpler models will suffice.. Why the unnecessary device level
complexity..?
Cheers
AG

Hi AG,
You may want to read through a series of articles by Kendall

see post# 30118

I know that he wrote a test suite for opamp models that tried to include PSRR / CMRR etc. I think this was about 2007 time frame.

However everything that he is writing about is for regular single ended opamps. PSRR and CMRR in Fully differential opamps is very different to PSRR in single ended opamps. Most simulations, even with input pair mismatch, will show very very low PSRR for a fully differential opamps. The PSRR of the first stage becomes CMRR of the following stage, so if you just measure one stage fully diff out, you get almost infinite PSRR.

Unfortunately the system PSRR for a fully diff system is often worse than a regular opamp (especially at low frequencies) because mismatch and asymmetry cause PSRR in fully diff opamps and this is hard to model properly.

Most fully differential opamps have about 60db to 70dB PSRR that is fairly constant for most of the frequency band, this is VERY different from the PSRR of a regular opamp.

You might want to play around with some PSRR measurements for fully differential opamp filters / PGA stages etc and get an idea about how Power supply variation / noise actually translates (over frequency) to an output error. The process is not that simple.

regards
Robert

Could someone let me know where I can find spice models for both 1N5811 and
1N6618?



Thanks,



Dan

--- In LTspice@..., "stm6823@..." <stevemorris@...> wrote:

When I try to run AD8336-2.asc in FILES&#92;AD8336 I get an error message that contains "Circuit: * C:&#92;Program Files&#92;LTC&#92;AD models&#92;AD8336&#92;AD8336-2.asc

WARNING: Node U1:U4_N24227 is floating."
But checking the .net file I do not find any NC.
Whats wrong?
Thanks in advance,
STM

Hello Steve,

Apologies for the earlier comment. I found your files in Files>Temp>AD8336, but there was no announcement or indication from you that they were there.

You schematic wouldn't run, but not due to the reason you gave. You had hard-coded the absolute path of the model file into the symbol, and of course when it is downloaded by someone else, it will, in general, not have the same path that you used. If you put the .included file into the .asc directory, you don't need any absolute path, as LTspice will always look there.

The error I got was "timestep too small... etc", which sometimes means the model is dodgy, but the schematic is probably at least syntactically OK.

I changed your schematic to something resembling the ADI application circuit, but still got a convergence error with an .op analysis, so I think the model file is the problem, but I'm afraid I don't have the time or inclination to debug it. Sorry.

Regards,
Tony

A suggested starting point is the following pdf. See:
<>

Howard

I know about time step control and its deviousness...! I think minimum
time step size puts an u necessary computational burden when little or
no activity is present.. it is better to have variable time step
resolution which is user guided...
Thanks
cheers
AG

--- In LTspice@..., Ganesan <dg1@...> wrote:

Thanks Nice idea...

This will work for transient analysis too, if LIST is supported in .tran....
Is list supported in .TRAN ?? This would allow you to have lot of data
points during fast edges and few during flat portions of the clock.
Cheers
AG
================================================================================================================
On 9/14/2011 2:48 PM, Tony Casey wrote:

<snip>
--- In LTspice@... <mailto:LTspice%40yahoogroups.com>,
Ganesan <dg1@> wrote:

I can run different ac simulations with different frequency resolutions
and range..
Is there a way to merge the plot files.?
Cheers
A. Ganesan

</snip>
Hello Ganesan,

I just thought of another, more direct way for you to do exactly what
you want without messing with raw files.

You need to use the .ac list... syntax; but why not put your
(unequally-spaced or indeed random) frequencies in an external file?

1. Calculate, or determine your list of frequencies in Excel and
export as a space delimited text file. Open the file in a text editor
and prepend ".ac list ". (Don't forget the space)
2. Save file as Frequency_list.txt
3. Add a SPICE directive .inc Frequency_list.txt
4. Add .op analysis directive (this will be ignored when the text file
is read).

Job done. I have uploaded a working example to Files>Temp.

I even surprised myself with this one. :-)

I guess this would work with a .dc list analysis too, but I don't see
any point in this.

Regards,
Tony




No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.914 / Virus Database: 271.1.1/3896 - Release Date: 09/14/11 01:34:00

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

Hello Ganesan,

This kind of interference is not needed or even desirable in .tran analyses because SPICE itself determines the step size depending on circuit activity.

Sometimes it needs some help, though, in deciding what's really important. For this we can set the minimum step size; or the cunning designer might put tripdt/tripdv limits into a bogus B source to force the step size reduction just in the areas in most interest. Another means of doing this is to have a high(er) frequency source that drives the variable step size algorithm. This could be gated to run only when it's necessary to increase the resolution.

Regards,
Tony