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Re: "Official" LTspice IV blog

 

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

I would venture to suggest that many people are unaware, as I was, that Linear Technology now has an official LTspice IV blog. This covers some of the frequently asked questions we get here, and is supported by several "Howto" videos.

Perhaps a link could be put on this group's homepage, although it runs the risk of simply adding to the list of resources people don't bother to use.

Oh, you can find it here:

Regards,
Tony
Hello Tony,

Thanks for this link. I placed a link to it in our Links-section.



Best regards,
Helmut
"Official" LTspice IV blog

 

I would venture to suggest that many people are unaware, as I was, that Linear Technology now has an official LTspice IV blog. This covers some of the frequently asked questions we get here, and is supported by several "Howto" videos.

Perhaps a link could be put on this group's homepage, although it runs the risk of simply adding to the list of resources people don't bother to use.

Oh, you can find it here:

Regards,
Tony
Re: I am using LTSpice for simulation of Buck and Buck-Boost converter. Is there a

 

--- In LTspice@..., "Michael" <friendofwisdom@...> wrote:

I am using LTSpice for simulation of Buck and Buck-Boost converter. Is there a way to find the 90 percent points of the output voltage curves I obtain as I want to calculate the time delay of the output voltage stabilising as I change the input voltage

Thankyou
Hello,

You can use the MEASURE-commands to find when the time when
voltage reaches a certain value.

Please take a look .MEASURE in the help pages of LTspice.

There are some examples using .MEASURE in our Files section.

Files > Tut > MEASURE



Best regards,
Helmut
Re: Help with E and G parts

 

Hello,

LTspice understands the syntax of the arbitrary E and G sources
from PPSICE. It's not necessary to translate it to a B-source
when you want run your old PSPICE designs.I recommend to use
the B-source bv and bi for your new designs.

Best regards,
Helmut
I am using LTSpice for simulation of Buck and Buck-Boost converter. Is there a

 

I am using LTSpice for simulation of Buck and Buck-Boost converter. Is there a way to find the 90 percent points of the output voltage curves I obtain as I want to calculate the time delay of the output voltage stabilising as I change the input voltage

Thankyou
Re: Help with E and G parts

 

I found an ok solution. It is to use "B" parts, and terminate the wires that I would have used as inputs to the E parts with resistors and node names. I can address these node names in the window they give you for the B part; "V= blah". Not as intuitive to understand when someone studies my schematic, but it works.
-Andy

--- In LTspice@..., Jim Wagner <wagnejam99@...> wrote:

Hi Andy -

Yes, you can have expressions. Actually, the Help will tell you a lot about this, including syntax and available functions.

Look in the section on E parts. I find it a bit obtuse to get to but search around a bit.

Jim Wagner
Oregon Research Electronics

On Aug 2, 2013, at 6:47 PM, a2n14d63y wrote:

Hi All,
I'm transitioning from Msim Pspice to LTspice.
Is there any way to do the following:
In Pspice, I could have an E or G part and have a math expression inside which could operate on the voltages of the input pins (e.g. V(%in2) was the voltage on the 2nd input pin). Is there a way to do that in LTspice?
It seems to accept only expressions for the GAIN, applied to the voltage difference between the two input pins.

I think I can accomplish that if I were to type directly into the netlist something like
E 1 0 value=(blah)
...where "blah" is the expression for the voltage at the output. However, I'm working with a schematic, where my E part is a symbol, and I'm not sure how to tell LTspice how to take the expression "blah" I enter into its "value" line and enter it into the netlist as
E 1 0 value=(blah)
...rather than
E 1 0 c1 c2 <gain>

Any thoughts?

Thanks,
Andy



[Non-text portions of this message have been removed]
Re: Help with E and G parts

 

Hi Andy -

Yes, you can have expressions. Actually, the Help will tell you a lot about this, including syntax and available functions.

Look in the section on E parts. I find it a bit obtuse to get to but search around a bit.

Jim Wagner
Oregon Research Electronics

On Aug 2, 2013, at 6:47 PM, a2n14d63y wrote:

Hi All,
I'm transitioning from Msim Pspice to LTspice.
Is there any way to do the following:
In Pspice, I could have an E or G part and have a math expression inside which could operate on the voltages of the input pins (e.g. V(%in2) was the voltage on the 2nd input pin). Is there a way to do that in LTspice?
It seems to accept only expressions for the GAIN, applied to the voltage difference between the two input pins.

I think I can accomplish that if I were to type directly into the netlist something like
E 1 0 value=(blah)
...where "blah" is the expression for the voltage at the output. However, I'm working with a schematic, where my E part is a symbol, and I'm not sure how to tell LTspice how to take the expression "blah" I enter into its "value" line and enter it into the netlist as
E 1 0 value=(blah)
...rather than
E 1 0 c1 c2 <gain>

Any thoughts?

Thanks,
Andy



[Non-text portions of this message have been removed]
Help with E and G parts

 

Hi All,
I'm transitioning from Msim Pspice to LTspice.
Is there any way to do the following:
In Pspice, I could have an E or G part and have a math expression inside which could operate on the voltages of the input pins (e.g. V(%in2) was the voltage on the 2nd input pin). Is there a way to do that in LTspice?
It seems to accept only expressions for the GAIN, applied to the voltage difference between the two input pins.

I think I can accomplish that if I were to type directly into the netlist something like
E 1 0 value=(blah)
...where "blah" is the expression for the voltage at the output. However, I'm working with a schematic, where my E part is a symbol, and I'm not sure how to tell LTspice how to take the expression "blah" I enter into its "value" line and enter it into the netlist as
E 1 0 value=(blah)
...rather than
E 1 0 c1 c2 <gain>

Any thoughts?

Thanks,
Andy
Re: Shot Noise Contributions From DC Currents

cbayona
 

No problems here;

Win7 X64
Chrome browser, the latest version.

At 03:21 PM 8/2/2013, you wrote:
When I try to download any of the files from I get a document not found message. Any ideas?

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

Hello All,

I have a simple amplifier model using a voltage controlled
voltage source with a parallel combination of R and C in the feedback. The noise analysis in LTSpice gives me the expected voltage noise spectral density due to the Johnson noise of the resistance. But I'm trying to add a DC bias current and see the shot noise that results, and it's not working. For example, if I put a 1 Amp DC bias at the negative node of the VCVS, I don't see the output noise change. I also tried using a behavioral model of the current using the white function, and that doesn't produce any noise at the output either.

Does anyone know how to simulate shot noise such as I'm trying to do?

Thanks in advance,
Darren O'Connor
--
Cecil - k5nwa
< > < >

Never take life seriously. Nobody gets out alive anyway.
Re: Comparison between TI's Filterpro and LTSpice

 

Hello Jerry,

The opamp's output was in the saturated region instead of the
linear region. I tried his example with the additional negative
supply voltage and discovered that the opamps oscillate.
I have then used the 4 digit values for all the resistors as
shown in the datasheet. Now it seems to be OK.

Files > Temp > bandpass1750.asc

Best regards,
Helmut

--- In LTspice@..., Jerry Lee Marcel <jerryleemarcel@...> wrote:

You must run an AC analysys to see the frequency response.
Your settings for transient analysis must be wrong - showing huge spikes
at the output.

Le 02/08/2013 11:08, resetpin a ¨¦crit :

Hi,

I uploaded the files into files/temp folder.

hope someone can give me a hint

Thanks in advance

Resetpin

--- In LTspice@... <mailto:LTspice%40yahoogroups.com>,
"resetpin" <resetpin@> wrote:

Hello,

I used Filter Pro from Texas instruments to get a Filter design from
my specifications. They are:
Gain: 5V/V (13,97dB)
Part: Ideal Opamp: Order 4 Stages: 2
Corner frequency Attenuation: 10,979dB
Allowable PassBand Ripple 1dB
Center Frequency: 1,75 kHz
Stopband Attenuation: -30dB
Passband Bandwidth: 100Hz
Stopband Bandwith: 600Hz

Filterpro proviced a schematic and Values for the parts and a
Gain-Frequency plot.

When I try to redo this in LTSpice the frequency corner freqency of
the filter is at the right positon but the gain is about -40db.

I wonder where the differences are and would like to show the
LTSpice *.asc File compared with the Texax Results but don't know how
to post them here in the group.

Maybe someone is willing to help me out and show me the differences
or the problem.

Thanks in advance

Resetpin


[Non-text portions of this message have been removed]
Re: Comparison between TI's Filterpro and LTSpice

 

You must run an AC analysys to see the frequency response.
Your settings for transient analysis must be wrong - showing huge spikes
at the output.

Le 02/08/2013 11:08, resetpin a ¨¦crit :

Hi,

I uploaded the files into files/temp folder.

hope someone can give me a hint

Thanks in advance

Resetpin

--- In LTspice@... <mailto:LTspice%40yahoogroups.com>,
"resetpin" <resetpin@...> wrote:

Hello,

I used Filter Pro from Texas instruments to get a Filter design from
my specifications. They are:
Gain: 5V/V (13,97dB)
Part: Ideal Opamp: Order 4 Stages: 2
Corner frequency Attenuation: 10,979dB
Allowable PassBand Ripple 1dB
Center Frequency: 1,75 kHz
Stopband Attenuation: -30dB
Passband Bandwidth: 100Hz
Stopband Bandwith: 600Hz

Filterpro proviced a schematic and Values for the parts and a
Gain-Frequency plot.

When I try to redo this in LTSpice the frequency corner freqency of
the filter is at the right positon but the gain is about -40db.

I wonder where the differences are and would like to show the
LTSpice *.asc File compared with the Texax Results but don't know how
to post them here in the group.

Maybe someone is willing to help me out and show me the differences
or the problem.

Thanks in advance

Resetpin


[Non-text portions of this message have been removed]
Re: Plans for more directories on search path? (I know, tired old subject)

 

Hello Andy,

I agree with Alzie regarding the problem with the place of the symbols. They have to be in the folder of the the design or
anywhere below lib&#92;sym at the moment.
One would not only need a path to the models. One would also
need a path to the symbols to conveniently solve your "problem".

Best regards,
Helmut

--- In LTspice@..., "a2n14d63y" <andydraudt@...> wrote:

Thanks Helmut,
I'll write to Mike.
Let's see, your solution (..speaker.lib) would require that the netlists of my models be placed in a .lib text file, yes? That would prohibit the viewing of the parts schematics by right-clicking on their symbol in the top level schematic, yes? If I'm wrong, please let me know!

rgds,
Andy

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

Hi Andy / Helmut

Ive had a similar issue, example:

I put my libs into:
c:&#92;users&#92;username&#92;LTspice4&#92;lib

My ckt sub dirs are just below
c:&#92;users&#92;username&#92;LTspice4

c:&#92;users&#92;username&#92;LTspice4&#92;cktname

Then i use .include ..&#92;lib&#92;libname.lib
up one dir and down into the lib dir for the lib files / search.
That way i can have all of my models / subckts in one place.

Doesnt for for symbols :-(
they still want to be in the program files path.

Al D.


On 08/02/2013 03:32 PM, Helmut wrote:
If you don't need that everybody can run your designs out
of the box, you could use an absolute path for your includes.

.lib C:&#92;mymodels&#92;speaker&#92;speaker1.lib

I admit that this is not a really good solution.
You could send an email to Mike with your wish. His email
address is given in the Help -> About of the LTspice program.
--


AC2CL

I do not think there is any thrill that
can go through the human heart like that felt by the inventor as
he sees some creation of the brain unfolding to success...
Such emotions make a man forget food, sleep, friends, love, everything.

- Nikola Tesla
Re: Comparison between TI's Filterpro and LTSpice

 

Are you still having problems after replacing the opamp with the generic
type?

Le 02/08/2013 11:08, resetpin a ¨¦crit :

Hi,

I uploaded the files into files/temp folder.

hope someone can give me a hint

Thanks in advance

Resetpin

--- In LTspice@... <mailto:LTspice%40yahoogroups.com>,
"resetpin" <resetpin@...> wrote:

Hello,

I used Filter Pro from Texas instruments to get a Filter design from
my specifications. They are:
Gain: 5V/V (13,97dB)
Part: Ideal Opamp: Order 4 Stages: 2
Corner frequency Attenuation: 10,979dB
Allowable PassBand Ripple 1dB
Center Frequency: 1,75 kHz
Stopband Attenuation: -30dB
Passband Bandwidth: 100Hz
Stopband Bandwith: 600Hz

Filterpro proviced a schematic and Values for the parts and a
Gain-Frequency plot.

When I try to redo this in LTSpice the frequency corner freqency of
the filter is at the right positon but the gain is about -40db.

I wonder where the differences are and would like to show the
LTSpice *.asc File compared with the Texax Results but don't know how
to post them here in the group.

Maybe someone is willing to help me out and show me the differences
or the problem.

Thanks in advance

Resetpin


[Non-text portions of this message have been removed]
Re: Plans for more directories on search path? (I know, tired old subject)

 

Thanks Helmut,
I'll write to Mike.
Let's see, your solution (..speaker.lib) would require that the netlists of my models be placed in a .lib text file, yes? That would prohibit the viewing of the parts schematics by right-clicking on their symbol in the top level schematic, yes? If I'm wrong, please let me know!

rgds,
Andy

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

Hi Andy / Helmut

Ive had a similar issue, example:

I put my libs into:
c:&#92;users&#92;username&#92;LTspice4&#92;lib

My ckt sub dirs are just below
c:&#92;users&#92;username&#92;LTspice4

c:&#92;users&#92;username&#92;LTspice4&#92;cktname

Then i use .include ..&#92;lib&#92;libname.lib
up one dir and down into the lib dir for the lib files / search.
That way i can have all of my models / subckts in one place.

Doesnt for for symbols :-(
they still want to be in the program files path.

Al D.


On 08/02/2013 03:32 PM, Helmut wrote:
If you don't need that everybody can run your designs out
of the box, you could use an absolute path for your includes.

.lib C:&#92;mymodels&#92;speaker&#92;speaker1.lib

I admit that this is not a really good solution.
You could send an email to Mike with your wish. His email
address is given in the Help -> About of the LTspice program.
--


AC2CL

I do not think there is any thrill that
can go through the human heart like that felt by the inventor as
he sees some creation of the brain unfolding to success...
Such emotions make a man forget food, sleep, friends, love, everything.

- Nikola Tesla
Re: Shot Noise Contributions From DC Currents: Oops!

 

Hmm, I reworked my way through the files directory and it worked this time.

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

Hello All,

I have a simple amplifier model using a voltage controlled voltage source with a parallel combination of R and C in the feedback. The noise analysis in LTSpice gives me the expected voltage noise spectral density due to the Johnson noise of the resistance. But I'm trying to add a DC bias current and see the shot noise that results, and it's not working. For example, if I put a 1 Amp DC bias at the negative node of the VCVS, I don't see the output noise change. I also tried using a behavioral model of the current using the white function, and that doesn't produce any noise at the output either.

Does anyone know how to simulate shot noise such as I'm trying to do?

Thanks in advance,
Darren O'Connor
Re: Shot Noise Contributions From DC Currents

 

When I try to download any of the files from I get a document not found message. Any ideas?

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

Hello All,

I have a simple amplifier model using a voltage controlled voltage source with a parallel combination of R and C in the feedback. The noise analysis in LTSpice gives me the expected voltage noise spectral density due to the Johnson noise of the resistance. But I'm trying to add a DC bias current and see the shot noise that results, and it's not working. For example, if I put a 1 Amp DC bias at the negative node of the VCVS, I don't see the output noise change. I also tried using a behavioral model of the current using the white function, and that doesn't produce any noise at the output either.

Does anyone know how to simulate shot noise such as I'm trying to do?

Thanks in advance,
Darren O'Connor
Re: Plans for more directories on search path? (I know, tired old subject)

 

Hi Andy / Helmut

Ive had a similar issue, example:

I put my libs into:
c:&#92;users&#92;username&#92;LTspice4&#92;lib

My ckt sub dirs are just below
c:&#92;users&#92;username&#92;LTspice4

c:&#92;users&#92;username&#92;LTspice4&#92;cktname

Then i use .include ..&#92;lib&#92;libname.lib
up one dir and down into the lib dir for the lib files / search.
That way i can have all of my models / subckts in one place.

Doesnt for for symbols :-(
they still want to be in the program files path.

Al D.

On 08/02/2013 03:32 PM, Helmut wrote:
If you don't need that everybody can run your designs out
of the box, you could use an absolute path for your includes.

.lib C:&#92;mymodels&#92;speaker&#92;speaker1.lib

I admit that this is not a really good solution.
You could send an email to Mike with your wish. His email
address is given in the Help -> About of the LTspice program.
--


AC2CL

I do not think there is any thrill that
can go through the human heart like that felt by the inventor as
he sees some creation of the brain unfolding to success...
Such emotions make a man forget food, sleep, friends, love, everything.

- Nikola Tesla

Re: Plans for more directories on search path? (I know, tired old subject)

 

--- In LTspice@..., "a2n14d63y" <andydraudt@...> wrote:

Hi All,
I'm new and trying to migrate from Msim Pspice over to LTspice. My big problem is with part libraries and directory search paths.

I do electro-mechanical-acoustic (thermal?) lumped element models using spice, and have many schematics I've made for parts (e.g. combustion model, speaker, alternator, nonlinear springs etc.). These get added to designs of larger systems.

In Pspice I could put my models into a directory and tell the program where to look for those parts. This is convenient, since my system-level projects were in many different project directories, and it would be absurd to copy all my part schematic files (about 50 parts) into each project directory. It seems that is not possible in LTspice, and I'd have to dump all my parts into the "sub" directory of the LT install tree?

So, my question is - are there plans to allow LTspice to address schematics stored in directories other than the current one or the LT install tree?

Thanks!
-Andy

p.s. I want the parts to remain as schematics, rather
than being just stored as netlists in a lib, because
they need to be graphically presented and tweaked regularly.
Hello Andy,

If you don't need that everybody can run your designs out
of the box, you could use an absolute path for your includes.

.lib C:&#92;mymodels&#92;speaker&#92;speaker1.lib

I admit that this is not a really good solution.
You could send an email to Mike with your wish. His email
address is given in the Help -> About of the LTspice program.

Best regards,
Helmut
Plans for more directories on search path? (I know, tired old subject)

 

Hi All,
I'm new and trying to migrate from Msim Pspice over to LTspice. My big problem is with part libraries and directory search paths.

I do electro-mechanical-acoustic (thermal?) lumped element models using spice, and have many schematics I've made for parts (e.g. combustion model, speaker, alternator, nonlinear springs etc.). These get added to designs of larger systems.

In Pspice I could put my models into a directory and tell the program where to look for those parts. This is convenient, since my system-level projects were in many different project directories, and it would be absurd to copy all my part schematic files (about 50 parts) into each project directory. It seems that is not possible in LTspice, and I'd have to dump all my parts into the "sub" directory of the LT install tree?

So, my question is - are there plans to allow LTspice to address schematics stored in directories other than the current one or the LT install tree?

Thanks!
-Andy

p.s. I want the parts to remain as schematics, rather than being just stored as netlists in a lib, because they need to be graphically presented and tweaked regularly.
Re: How to change plot dimensions?

 

That did it! Thanks.

a simple 1e6*V(inoise)/1V*sqrt(1Hz) does make the plot 'dimensionless' with magnitudes in the expected range

Small remaining point, if I try to shift the plot by adding, doesn't work as expected.
for example,
1e6*V(inoise)/1V*sqrt(1Hz)
and then
1e6*V(inoise)/1V*sqrt(1Hz)+10
does NOT shift the display upwards by 10 instead shifts upward by sqrt(sum(squares)), which makes sense, but doesn't do exactly what I expected.

even adding parantheses to offset the calculation
(1e6*V(inoise)/1V*sqrt(1Hz)) +10
still maintains the sqrt(sum)

not a deal breaker, just interesting.


--- helmutsennewald@... wrote:

From: "Helmut" <helmutsennewald@...>
To: LTspice@...
Subject: [LTspice] Re: How to change plot dimensions?
Date: Fri, 02 Aug 2013 14:49:49 -0000



--- In LTspice@..., Macy <macy@...> wrote:

Plot noise vs frequency and the plot comes out in dimensions of
V/sqrt(Hz)
which is correct.

However, in my circuit I would like to have it plot in another dimensions [same number value, different name]

How to change?

I successfully get rid of V by dividing by 1V, but there doesn't seem to be any equivalent to get rid of sqrt(Hz)

Anybody made a noise plot 'dimensionless'?

Hello Macy,

I didn't know how it works before. I tried and had luck.

V(onoise)*sqrt(1Hz)

Best regards,
Helmut
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