Re: Trying to create a lookup table without any success
There seems no need for the 100 V source,
still less the 10 ohm load, and your .TRAN command makes no
sense, since nothing varies, and the 1ps max time step is just
bizarre.? You can't specify the output of a B source in the way
you have written it, and in fact I don't think it will do what
you want anyway. However, what you want isn't at all clear. What
do you want the look-up table for?
You wrote: 'I wish it will take
the voltage and the output of V1' . The output of V1 IS 'that
voltage', so it's impossible to tell what you meant to do.
Best wishes
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates
Rayleigh, Essex UK
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Hello,
I am trying to generate a value from a lookup table
but unfortunately I am doing something wrong and ltspice
complains. I have a V1 voltage that generates constantly
100V and I use a behavioral voltage source that I wish
it will take the voltage and the output of V1 and by
going through a table it will return a value. Any ideas
about that?
Thansk in advance!
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Re: Trying to create a lookup table without any success
Hello,
Example:
V-source V1 connected between net "abc" and net "GND".
V1 abc 0 SINE(....)
Bv-source
V=table(V(abc), -100,20, -50, 15, 0, 5, 50, 20, 100, 30)
LTspice will use linear interpolation between the table-values.
Best regards, Helmut
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I actually found this spice model?
.model D1N4733 D(Is=1.214f Rs=1.078 Ikf=0 N=1 Xti=3 Eg=1.11
+ Cjo=185p M=.3509 Vj=.75 Fc=.5 Isr=2.601n Nr=2 Bv=5.1 Ibv=.70507
+ Nbv=.74348 Ibvl=4.8274m Nbvl=6.7393 Tbv1=176.471u)
but it doesn't work.
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A simple web search gives at least two hits
for a spice model.
Best wishes
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates
Rayleigh, Essex UK
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Hello,
? ? ? ? ?I need a spice model of 1N4733A zener diode.
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Re: FFT in LTspice Mac version
Hello,
> Do you know if there are ways to fix this bug?
Yes, convince the developer to fix it. :-)
Therefore write a bug report to LTspice@....
You could additionally ask this question on the official forum of Analog Devices.
Best regards, Helmut
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Trying to create a lookup table without any success
Hello,
I am trying to generate a value from a lookup table but unfortunately I am doing something wrong and ltspice complains. I have a V1 voltage that generates constantly 100V and I use a behavioral voltage source that I wish it will take the voltage and the output of V1 and by going through a table it will return a value. Any ideas about that?
Thansk in advance!
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Re: FFT in LTspice Mac version
I have the same problem with fft on macOS Mojave 10.14.1
Do you know if there are ways to fix this bug??
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Model for F0800LC180 PUK diode
I am looking for a model for that diode or the way to obtain it. I like that diode because its price is not so high and reach 775A averaged and 1800V. The specs can be found here, appear the Trr that is important in the design of a high power rectifier:
?
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Re: Saving and restoring inductor current
>? ?A smarter way around this problem might be to select the test?> frequency points and cycles used such that the test and? > switching frequencies are always related to each other? > by whole numbers ratios (for the parametric output plot,? > there is no need that frequency points be evenly spaced).
I've experimented with an injected signal which contains the sum of all test frequencies one wants to inspect. It is then easy to? sync?to the switching frequency. The FFT of the output directly? correlates to the amplitude Bode diagram (to get the phase is a bit more work). It appears to work, but I've had no time to analyze it in depth yet.?
For the experiment I used an?experimental SPICE?that? accepts a fixed timestep.
-marcel
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Re: Saving and restoring inductor current
Hello Alexander,
Your English has improved noticeably over the years.
My great-grandfather was third generation Russian whose father became an American when Alaska was purchased.? His great-grandfather migrated to Russia from Germany and was the captain of the first ship when the Russians explored and colonized Alaska.? My great-grandfather died before I was born, but his wife (who was half Danish and half Japanese) lived well into her nineties.? She died when I was a young man in university, so she was a favorite grandmother to me when I was a boy.
She taught me a few Russian phrases and I grew up eating pickled herring (the creamy kind), borscht, black caviar, black tea from a large samovar, yeast-dough piroshki, and praniki (hard, flat, white mint flavored cookies) as well as many other Russian foods without names to me (such as pickled onions, beets and cabbage).? It makes my mouth water thinking about them.? Of course I learned to like many Japanese foods as well.
---In LTspice@..., <BordodunovAlex@...> wrote : Hello analogspiceman. ? Thank you for enlightening me. I added the following to my collection of models: ? .subckt Lrememb 1 2? .param ? L=1 Rser=1m Rpar=1/Gmin ic=0 C1 3 0 {L} Rser={1/Rpar} Rpar={1/Rser} ic={ic} G1 1 2 3 0 1 G2 3 0 2 1 1 .ends Lrememb ? Bordodynov.
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Re: Saving and restoring inductor current
Hello Vlad and Alexander (and Helmut, who is always such a gentleman expert),
Thanks for noticing.? The things that interest me most about LTspice are always so arcane and often not of interest to most users so it is nice when some of the more sophisticated group members take notice (kind of like the situation with Adrian Immler and his amazing, improved tube models).
I haven't tried it yet, but thought this "dual inductor" would be useful in a improved version of LTspice's example file transient domain loop-gain analyzer that uses .measurement statements because it could perhaps save a lot of time lost recalculating steady state at each new frequency step of the analysis.
In his Ridley Works software (was Power 4-5-6), Ray Ridley uses a seemingly improved variation of the post processing loop-gain analyzer technique for switching circuits (his Excel engine generates a LTspice version of the subject schematic).? His software requires 32 bit Excel and all my machines are 64 bit, so I haven't been able to try his free, limited, but complete example (for buck converters only).? Thus I haven't been able to examine exactly what his software does to determine if it has improved upon the standard methods that are used in the LTspice example file.
If you can, please try out his free software and report back what you think of it.? It also generates superb, elegant and efficient LTspice models for winding and core loss (something I have done on a case by case basis as needed, but his software has generalized automated method of doing so).? We could probably duplicate his methods.
The transient domain loop-gain analyzer essentially performs a discrete Fourier transform at each analysis frequency point.? This can be problematic with much injected fractional cycle noise if the switching frequency and the test frequency do not both end on exactly whole periods.? The usual solution to this problem is to apply a complicated and computationally expensive tapered windowing function to minimize the deleterious effects of fractional alignment.? A smarter way around this problem might be to select the test frequency points and cycles used such that the test and switching frequencies are always related to each other by whole numbers ratios (for the parametric output plot, there is no need that frequency points be evenly spaced).
My goal is to create a transient domain frequency response analyzer for switching power supplies in LTspice that produces as clean and noise-free results as does SIMPLIS while still running reasonably quickly.
---In LTspice@..., <imbvlad@...> wrote : Hello analogspiceman
LTspice can save and restore node voltages, but not branch currents. This means that by using ".savebias time=<tstop>" and ".loadbias" a simulation with inductors is only partially saved and restored because inductor currents are ignored. It occurred to me that by making a "dual inductor" using current sources and a capacitor, one might trick LTspice into saving "inductor" currents. The inductor dual is very simple and can be a subcircuit with the inductor symbol edited to represent the dual inductor with the expected symbol.
Don't how this compares speed-wise and coupled inductors would require an extension, but this technique might prove useful in certain stepped simulations that could run much quicker if the operating point did not need to be refound each time.
That's a nice trick, thank you. The penalty shouldn't be that much if not too many inductors are used, for example a SMPS could really use that. Even filters that are not too large could benefit from this.? Coupled inductors might be trickier to set up, though. -- Vlad
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Re: Using BV exp(), log() for numerical compression ,wrong result ?
I suppose you do realise that you can make one or both axes of a
plot logarithmic. You can also plot, for example log(V(out) on a
log axis, so get a log-log scale, using waveform arithmetic.
Best wishes
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates
Rayleigh, Essex UK
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Hi, Andy:
Before your explanation, I didn't notice "complex
logarithm" is a special case, maybe not supposed to be
supported by any SPICE.
About the compression application, I didn't really have
the complete idea, maybe it would be like the,....
For example, when someone reading a book, the edge on
every page often empty, and be used to sketch some thing
on, some graphs/pictures to decorate the layout of the
page. They often are not the primary parts.
To analogy, if there are some main data, which
typically are numerical values, and has its general scale
on the range of greater than 0.01, though its format could
support to very least 1e^-16, or some, such that, maybe I
could merge those loged numbers secretly into the "main
data", and leak .... to somewhere who concern it, without
interference others who typically don't care those smaller
values which is under 0.01.
Just some ignorant ideas. I didn't implement it yet.
.
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Re: Adding A Potentiometer
I have uploaded the file potenziometro.asc as an example of a
potentiometer simulation.
Regards.
Vincenzo Varoli
--
Prof. Vincenzo Varoli
Politecnico di Milano Dip. Energia
Via G. Ponzio 34/3 I20133 Milano Italia
Tel. 0223996393 FAX 0223996309
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See my reply, "How To Add Potentiometer".
Andy
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Re: Adding A Potentiometer
See my reply, "How To Add Potentiometer" .
Andy
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Re: Edge triggered b-source logic and integrated averaging in LTspice
Hello Vlad (and other group members),
Earlier today I received a message from Mike.? There is a now a new update of LTspice available in which this minor bug has been squashed. ---In LTspice@..., <analogspiceman@...> wrote : Hello Vlad,
I noticed that bug and reported it several days ago. Perhaps it would help if you reported it as well. It only is a problem for "B I=" sources that include a defined function and that specify both Rpar and Cpar. Either one alone is okay.
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"snopro.olmstead23" (Surpher) asked how to add a potentiometer in LTspice.? Your message hasn't shown up here yet.? I guess Yahoo's servers are still working on it.? Please no need to send the same question over and over.
Potentiometers don't come with LTspice.? Nor with SPICE.
Consider whether you really really need one.? Electrically, a potentiometer is just two resistors in series.? Two reasons why you might want one anyway are:? (1) You want your schematic to look pretty; or:? (2) You want to .STEP your simulation through a range of settings.? Otherwise, I can't think of a reason for needing one, but there might be one.? If your circuit has a potentiometer and you don't need to do either (1) or (2), then just calculate the two resistor values, and you're all set!? Much simpler.
However, don't give up yet.? There are a number of potentiometer symbols/models that have been uploaded to this group's Files section.? Choose one, then stick with that one.? Start here:
? ? Files > Lib > Potentiometer ? ??
or here:
? ? Files > Tut > Potentiometer ? ??
and there are others too.? As I say, pick one and go with that one.
Your next step depends on which one you downloaded and plan to use.? This might help:
If you put the symbol file (*.asy) in the same folder with your schematic, then do this: ? (a) Open the schematic. ? (b) Go to Add Component. ? (c) At the top of the pop-up, there is a "Top Directory" with two choices: LTspice's library, and the current directory.? Change it to the current directory. ? (d) Now the potentiometer symbol is a choice and can be added to the schematic.
Whether you need to add a .lib file reference, that depends on the potentiometer you've chosen.? If you need to add a .lib file yourself, add the following to your schematic (as a SPICE Directive):
? ? .inc filename.ext
where filename.ext is the actual filename of the .lib file -- so it might be something like "potentiometer_standard.lib" or "potentiometer.sub".
The next thing is to right-click on the attributes next to the potentiometer symbol, to set its value and the amount of rotation you want.? Hopefully that's obvious, because it depends on which one you've chosen.
If you have already downloaded one of the potentiometer symbols and can't get it to work, then please provide more information.? Tell us exactly which one of the potentiometer models you chose.? Preferably, you should ZIP your schematic AND the potentiometer symbol file AND its model file, into one .ZIP file (that's .ZIP not .RAR or other!), and upload it to the group's "Temp" folder so we can see what you've done so far.? Then write another message saying that you did that.
Regards, Andy
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Re: Saving and restoring inductor current
Hello analogspiceman LTspice can save and restore node voltages, but not branch currents. This
means that by using ".savebias time=<tstop>" and ".loadbias" a simulation
with inductors is only partially saved and restored because inductor
currents are ignored. It occurred to me that by making a "dual inductor"
using current sources and a capacitor, one might trick LTspice into saving
"inductor" currents. The inductor dual is very simple and can be a
subcircuit with the inductor symbol edited to represent the dual inductor
with the expected symbol.
Don't how this compares speed-wise and coupled inductors would require an
extension, but this technique might prove useful in certain stepped
simulations that could run much quicker if the operating point did not need
to be refound each time. That's a nice trick, thank you. The penalty shouldn't be that much if not too many inductors are used, for example a SMPS could really use that. Even filters that are not too large could benefit from this. Coupled inductors might be trickier to set up, though. -- Vlad ______________________ ltspicegoodies.ltwiki.org -- holding, among others: a universal analog/digital filter, block-level models for power electronics (and not only), math blocks with a more stream-lined approach, some digital ADC, DAC, (synchronous-)counter, JKflop, etc.
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Eric asked about the file "74hc_v.lib", needed in a downloaded simulation.
I don't know if you found the answer to your question already (the replies I received might not be in order).? However, the file you were looking for is in the group's Files, here:
? ? Files > Lib > Digital 74HCxxx > 74HC_v.lib
? ?
I remind people to try the "Table of Contents" file (all_files.htm) when something like this is needed.
By the way -- the schematic uses the 74HC194 but not the original/bipolar 74194, despite the name of the schematic.? I guess that schematic was an answer to someone's question and you'd have to go back to that question (99370) if you wanted to see why the names didn't agree.
Regards,
Andy
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Re: Saving and restoring inductor current
Hello analogspiceman. ? Thank you for enlightening me. I added the following to my collection of models: ? .subckt Lrememb 1 2? .param ? L=1 Rser=1m Rpar=1/Gmin ic=0 C1 3 0 {L} Rser={1/Rpar} Rpar={1/Rser} ic={ic} G1 1 2 3 0 1 G2 3 0 2 1 1 .ends Lrememb ? Bordodynov.
27.11.2018, 04:52, "analogspiceman@... [LTspice]" <ltspice@...>:
?
LTspice can save and restore node voltages, but not branch currents.? This means that by using ".savebias time=<tstop>" and ".loadbias" a simulation with inductors is only partially saved and restored because inductor currents are ignored.? It occurred to me that by making a "dual inductor" using current sources and a capacitor, one might trick LTspice into saving "inductor" currents.? The inductor dual is very simple and can be a subcircuit with the inductor symbol edited to represent the dual inductor with the expected symbol.
.subckt L 1 2
.param L=1 Rser=1m Rpar=1/Gmin
C1 3 0 {L} Rser={1/Rpar} Rpar={1/Rser}
G1 1 2 3 0 1
G2 3 0 2 1 1
.ends L
This seems to work well and each run picks up where the previous run left off.? Here is a test simulation.
V1 1 0 1 AC 1
X1 1 2 L L=1m
C2 2 0 1
R1 2 0 1k
.tran 0 50 1u uic
.savebias bias.txt time=49.9
.loadbias bias.txt
Don't how this compares speed-wise and coupled inductors would require an extension, but this technique might prove useful in certain stepped simulations that could run much quicker if the operating point did not need to be refound each time.
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John Woodgate