Installing and using LTspice IV (now including LTXVII), From beginner to advanced

[kees52]

I have the same version, I get this with a model while it did work before. I did send previous post to mike so he can look.

 

[kees52]

Hi all

Can someone tell me if I can do a intermodulation sweep and a PSRR measurement with ltspice, and how to do that?.

thanks in advance.

 

[Mooly]

PSSR can be done by adding a simulated PSU and calculating in the normal way the amplitude of any ripple on the output. See attached file for the PSU details.


Bob C has an excellent write up in his book on how to do the CCIF 19kHz + 20kHz intermodulation test in a sim and how to infer the results.

 

[kees52]

Hi Mooly Thank you very much, I had try a extra voltage source with 1 volts 100 hz sinus in series with the normal 40 volts source, I did get a ripple.

But I go try your setup and read the bob c.

Oh yes almost forgotten I do sim class D, maybe these are more difficult.

have a nice and sunny weekend, earth warming up do not look so bad, summer here.

 

[Hans Polak]

I've noticed that my indexed files keeps growing and growing. This behaviour has been going on for months and I suspect LTXVII might be the culprit with its duplicate lib files appearing in documents and the program files.

I checked the number of indexed files this morning and it was over 19,000 in size. I get W10 to rebuild the index and sure enough, that total drops by over 7000. Now, through the course of the day the total is slowly increasing again. It will take a week or two (or three ) to get back to where it was. That number of 7000 or so seems to approximate to the number of items in the documents .lib folder, at least that is the number of items I see clock up if I copy the folder to a USB drive.

Hi Mooly,

You're a lucky guy with only 19.000 indexes.
When I checked my W10 system, I had over 90.000 indexes !

Hans

 

[Mooly]

That's a fair few files you have there I wonder what your total would be if the index was rebuilt ?

 

[FdW]

Here 191799 files

 

[kees52]

Hi Mooly Thank you very much, I had try a extra voltage source with 1 volts 100 hz sinus in series with the normal 40 volts source, I did get a ripple.

But I go try your setup and read the bob c.

Oh yes almost forgotten I do sim class D, maybe these are more difficult.

have a nice and sunny weekend, earth warming up do not look so bad, summer here.

I presume, this is what I must see when simulation with a supply like you say? because I see clearly a ripple on the output signal looks like this works fine.

So I learn again some more ltspice tricks.

thanks

 

[Hans Polak]

Just as a piece of information.

I have a complex model with over 60 transistors, lots of Leds and Diodes and 8 OPA's.
In LTspice XVII a .tran takes 36 seconds to process a square wave.
Processing a copy of this very model in LTspice IV takes 164 seconds for the same calculation.
That's a factor 4.5 faster in favour of LTSpice XVII !!

Hans

 

[Mooly]

I presume, this is what I must see when simulation with a supply like you say? because I see clearly a ripple on the output signal looks like this works fine.

So I learn again some more ltspice tricks.

thanks

That's it

This shows the amp with just 100uF reservoir caps when delivering around 1 watt at 1kHz. Second shot is with the input signal removed. It is valuable to also look at each rail in turn to see where the worst injection points are.

 

[kees52]

That's it

This shows the amp with just 100uF reservoir caps when delivering around 1 watt at 1kHz. Second shot is with the input signal removed. It is valuable to also look at each rail in turn to see where the worst injection points are.

I did with higher output power, because it is a class d, now making a hysteric window for open loop class D probing supply ripple making high PSRR.

THanks for your help..

regards

 

[kees52]

Just as a piece of information.

I have a complex model with over 60 transistors, lots of Leds and Diodes and 8 OPA's.
In LTspice XVII a .tran takes 36 seconds to process a square wave.
Processing a copy of this very model in LTspice IV takes 164 seconds for the same calculation.
That's a factor 4.5 faster in favour of LTSpice XVII !!

Hans

It is also 64 bit, and can calculate faster. If all is good crashes do not occur anymore in .RAW window, I did find the bug and writer has correct it.

 

[kees52]

You guys may tell me why I get the triangle output on the amp output resistor 8 ohms, and the amp output from the triangle generator??? these kind of strange behavior the 64 bit ltspice has in more ocassions getting strange outputs.

it is not such a problem but can be a bug ore more bugs.

 

[merlin el mago]

How to install "tubelibrary.txt"?

 

[euro21]

How to install "tubelibrary.txt"?

Include it.
Press "S" button (Spice directive) and write:
.inc tubelibrary.txt

 

[merlin el mago]

I couldn't find the "S" button?

 

[euro21]

I couldn't find the "S" button?

Between "A" and "D" in the keyboard. pp

 

[kees52]

Hi All

Because of the simulation with a integrator who is capacitive coupled the dc do change slowly in simulation until it is set, therefore I need to set a 3 mS before sim starts, is it possible to let ltspice now cap is already charged?, the dc output of integrator do got to seting very slow making long sim time.

thanks.

 

[kees52]

This afcouse is not possible!!! these are the signals on output, upper trace is A middle is B and lower is C.

This behavior is really annoying, making long sims useless, because needs to restart ltspice before it is oke again, so much bugs in 64 bit version? happenly most go oke, but it this is quite common.

it needs to be as in pic two, the two upper levels, upper is B and middle is B and C as that is oke..

regards

 

[kees52]

Do someone now how to include a 90 degree delay in the ltspice voltage sources? in mine case a triangle. Thanks.