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

feabyl wrote:

How to implement an expression D(t)=D(t-1)+ a ?

Is that D(t-1) as in D(t - 1sec)?

If so, you can implement a 1 second time delay in either of two ways:

1. A (properly terminated) lossless transmission line (T-element) with a
delay of 1 second.

2. A behavioral source (B-element) with a delay of 1 second.

If the '-1' is supposed to represent the previous internal timestep in
LTspice, I don't think there is a way to do that. (But I'm not saying it
is impossible.)

Regards,
Andy

Thank you for the options suggested.Could you give an idea how to implement 1 sec delay using B-element.

jason.vanryan <andrewc.russell@...> wrote:

Hello, have not posted here for quite a while!

Didn't you post here just this morning?

I have a number of schematic files that have a small lock icon just to the

left of them when I display the files in a folder. When I select all the
files and drag them into a USB memory stick folder, only the unlocked files
copy across. Any idea what I am doing wrong?

Please don't post the same question multiple times without bothering to
read what has already been posted in response to your question.

What is your computer operating system / version? In what folder are the
schematic files you are copying? Are any programs running when you attempt
to do the copy?

Andy

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

Hello,

I am trying to make a power supply using a 3722-1.

The input is 18 to 30Vdc and output is 165V@...

The issue that I am having is that at low input voltages like 24V or 18V the power supply is not able to reach full output level. At 30V the output level is reached but regulation is poor.

There's nothing wrong with the model, as such, but there seems to be a couple of issues with the circuit that you're simulating.

If you overcompensate it, you'll get a better idea about what is going on in the power train, as the control circuit will not be responsible for cycle by cycle variations.

There should be an overcompensated example posted in the temp files shortly.

In the working model, there is a shoot-through current occurring quite regularly. I don't know whether this is the result of intentional values placed in the drive delay circuits.

In real life, such spikes would invoke irregular limiting behavior in the 3722 that you'll want to avoid.

As to power throughput with reducing input voltage, you should take a look at the current waveforms and decide for yourself where the limitation lays.

RL

Hello, have not posted here for quite a while!

I have a number of schematic files that have a small lock icon just to the left of them when I display the files in a folder. When I select all the files and drag them into a USB memory stick folder, only the unlocked files copy across. Any idea what I am doing wrong?

Thanks

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

Herbert (<afu@...>) wrote:

Is it possible to give LTSPICE a value by a formula expression based on

a table ( interpolation???) ?

Yes you can. But the problem is that it tends to work well in .AC analysis
but not in .TRAN analysis.

Also, many inductive devices with iron-based cores are nonlinear, which
makes them difficult (impossible) to quantify in the frequency domain alone.

Andy

Andy,

Nonlinear inductor work fine in the frequency domain. The first thing LTspice does for an .AC analysis is to find the DC operating point. Then any nonlinear devices are linearized at their operating point. .AC analysis, by definition, is a small signal linear analysis and it does not deal with nonlinear devices other than noted above.

Rick

--- In LTspice@..., "highfidelityinc" <steve54@...> wrote:

Forgive me for asking such a basic question but is it possible to link several symbols (e.g. *.asy files) to the same package? I mean, say I have a quad opamp. I would like to position each of the 4 opamp individually on the schematic and maybe the power and ground to a separate symbol. Then when I export the Netlist to draw the PC layout, they are all assigned to the same package.

Currently I just make one big symbol with all four opamps and power and ground. But by doing that I cannot lay out my schematic as clearly without creating a rat nest of interconnecting wires.

Many thanks for your advice.
Steve

Hello Steve,

You could name the opamps U4A, U4B, U4C, U4D and do some
extra post-processing to modify the PCB-netlist.


Maybe this earlier discussion will help.

"pcb layout s/w for use with ltspice"

It starts with message #52018 and ends with the interesting
message/offer #52082 from Peter.

Best regards,
Helmut

Forgive me for asking such a basic question but is it possible to link several symbols (e.g. *.asy files) to the same package? I mean, say I have a quad opamp. I would like to position each of the 4 opamp individually on the schematic and maybe the power and ground to a separate symbol. Then when I export the Netlist to draw the PC layout, they are all assigned to the same package.

Currently I just make one big symbol with all four opamps and power and ground. But by doing that I cannot lay out my schematic as clearly without creating a rat nest of interconnecting wires.

Many thanks for your advice.
Steve

Hi Andy,

as the game plays in the RF ham area, the AC view will be the right way !

I will try to find out, how it will work with the a table .

Thanks

Herbert

Am 14.07.2013 18:08, schrieb Andy:

In message <krbus2+ba2e@...>, dated Sun, 7 Jul 2013, Herbert <afu@...> writes:

dows anybody have an idea for modelling a inductance with a permeability in dependency of frequency ??

I want to go right back to the beginning. Because you gave very little information, people have assumed various things and that can make the whole thing complex and confusing.

First of all, what frequency range are we in, and what is the material whose permeability depends on frequency? Secondly, is this material significantly lossy in that frequency range or not?

For example, if you are looking at nickel-iron at audio frequencies, the losses are secondary, but if you are looking at ferrites at radio frequencies, then whether the losses are significant or not depends on which grade of ferrite you are looking at.

If the losses are NOT significant, then why bother with permeability? The inductance is proportional to it, so you can just use a table of inductance against frequency.

If the losses ARE significant, you CAN model as L and R parallel but both need a table of values against frequency.
--
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
Why is the stapler always empty just when you want it?

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

Herbert (<afu@...>) wrote:

Is it possible to give LTSPICE a value by a formula expression based on

a table ( interpolation???) ?

Yes you can. But the problem is that it tends to work well in .AC analysis
but not in .TRAN analysis.

Also, many inductive devices with iron-based cores are nonlinear, which
makes them difficult (impossible) to quantify in the frequency domain alone.

Andy

In message <krufd8+qauu@...>, dated Sun, 14 Jul 2013, jason. vanryan <andrewc.russell@...> writes:

I am trying to copy my circuit files from one computer to another. Some of the files have a little lock icon next to them. These files will not copy across to a USB drive. If I open them individually and then save them to the USB drive its ok.

What am I doing wrong?

You have probably got your files in C:&#92;Program Files&#92;... and Windows will not let you copy files from there to another computer.
--
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
Why is the stapler always empty just when you want it?

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

Hello,

I am trying to copy my circuit files from one computer to another. Some of the files have a little lock icon next to them. These files will not copy across to a USB drive. If I open them individually and then save them to the USB drive its ok.

What am I doing wrong?

Hi Alzie and aall the others which answered,

Alzie is nearly right with the way of explanation what I have seen, but
it is not possible to describe the behaviour by S?ICE just with a
parallel resistor.
On that page under B you will
find a real measured Z-Plot in vetorial notation ( with the phase on the
right side ) and the initial measurement of inductivity of 20uH. The
core is lossy in the range of the plot ( Amidon Mat 43) and the model
with jus the parallel resistance does NOT do enough or right. So my idea
was to define the permeability in its complex form and give a table of
values or artificaly evaluated polynom with permeabilty factors over
frequency.

Is it possible to give LTSPICE a value by a formula expression based on
a table ( interpolation???) ?

Thanks in advance

Herbert


Am 09.07.2013 14:48, schrieb alzie:

Hi Herbert

On 07/09/2013 12:45 AM, sawreyrw wrote:

dows anybody have an idea for modelling a inductance with a
permeability in dependency of frequency ??

A simple model would be an inductor in parallel with a resistor.

Most ferrous cores behave well up to a cross over frequency at which
the perm drops and they become very lossy.
The loss dominates above that freq and
the inductor looks pretty much like a resistor that
is flat with freq.

--

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

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

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

still requires a LOT of fussing around.

bouncing between wide band .noise and 'regular' .ac analysis and the .ac using specific values requires storing on the schematic a list so long that it makes the schematic the size of a postage stamp in auto size. perhaps a plus sign on the first of a few lines will allow wordwrap - narrow width with long list.

getting an output requires click file, export, then select real, imaginary ofrmat, and then YES overwrite existing *.txt file.

Then run a script in octave to grab all the data, do the conversion to something meaningful and evaluate whether I did what I wanted to.

But, other than all this mucking about, I CAN get my answers!! whew! it gets me there.

Are you talking about GNU Octave and are you working under windows or linux?
If you are working under linux then you may be able to write a netlist for ngspice. You would then be able to run all your analysis commands together between control statements, e.g:

.control
all analysis statements here
.endc

More examples here:



But then you would have to post on a ngspice forum.

Dear Andy and Dear Fred

Firstly, I really cannot explain my feelings when I see that you do your best for to solve my problem, I thank you very much.
Couple of days ago, I was in vacation and I was thinking that the problem can be from Voc and Isc calculators and actually when I separate the Evoc and Eisc from the main circuit and just grounded them, the distortion disappeared but again it is not working for 2 cells in series while by making two cells in series the open circuit voltage should be doubled which is not happening (it was happening before I separate the calculators but with distortion) !
For making the things more clear, I draw the circuit in Paint ( so ashamed that cannot work with schematics and SPICE good).



and corrected circuit



But solving this issue is a real challenge for me ! maybe there is only a mistake on nodes ! while it works in parallel not in series !

Again I should say that I really appreciate your helps so far thank you thank you and thank you again.

Kind regards
Hamed

I don't recall giving initial conditions for the cap, so if I did not
shouldn't the cap start



In a fully discharged state?

No, it would not.

The first thing LTspice does is find the initial operating point. Voltage
sources are set to their DC values, and effectively LTspice "waits" until
everything stabilizes, before proceeding.

Remember that a DC voltage source is unchanging. Ever. It's as if your 6V
battery was created with the Big Bang and has been sitting at exactly 6V
ever since that time. In effect you got what you asked for. If you wanted
the circuit to start at 0V you should have set your battery to that.

There are a few ways to tell LTspice to behave differently. One is to set
the voltage source to start at 0V and turn on at slightly after t=0.
Another is to instruct LTspice to not find that initial operating point.

Andy

On Sat, 13 Jul 2013 23:01:59 -0400, Julio wrote:

I am looking at simple RC circuit with a time constant of 1 sec and a 6 V
battery.

Doing a transient analysis, at t=0 the capacitor is already fully charged
at 6.0 volts!

I don't recall giving initial conditions for the cap, so if I did not
shouldn't the cap start

In a fully discharged state?

Look at the .tran card (it's on the schematic.) Right click
it and look near the bottom of the dialog box to find "skip
initial operating point solution" and check it so that this
step will be skipped. Then re-run the solution.

Jon

I am looking at simple RC circuit with a time constant of 1 sec and a 6 V
battery.







Doing a transient analysis, at t=0 the capacitor is already fully charged
at 6.0 volts!



I don't recall giving initial conditions for the cap, so if I did not
shouldn't the cap start



In a fully discharged state?





Sincerely,





Julio

--- In LTspice@..., "haubmi1" <Michael.Haub@...> wrote:

--- In LTspice@..., "Helmut" <helmutsennewald@> wrote:

--- In LTspice@..., "haubmi1" <Michael.Haub@> wrote:

Hello,

there was a feature to have a resistor with different value for .ac and .tran .

e.g.:

R 1 2 1u AC 1Gig

That was a resistor that was 1uOhm in .TRAN and 1GOhm in .AC.
This does not work anymore?

That was a very handy feature to switch in a loop gain probe in .AC which is not fisible in .TRAN .

Was this feature removed by accident or is that intended?
Did the syntax change?
Or is it my error?

michael

Hello Michael,

It's still working. Trust me.
Please show me your example and I will repair your schematic.

Best regards,
Helmut

Hello Helmut,

i have uploaded Files>Temp>loopgain-probe-test.zip.

I don't know what was the exact problem as a similar spice desk at work did not run as expected. Here at home the loop-gain probe did run in the new spice desk i made, but only with the alternate solver.
If you like you can have a look at it and tell me why it needs the alternate solver for DC bias point.

I will check on Monday why it did not run correctly at work.

Cheers,
Michael

Hello Michael,

You have used resistance values of 1f. That's a very bad idea.
Change it to 1u and the simulation will run with the normal
solver. Lesson from today: never use femto-Ohms.

.subckt simple-openloopgain1 in out params: reakt=100Gig
L1 in out {reakt} Rser=0
C1 2 1 {reakt} Rpar=0
R1 in 2 100G AC 1u
R2 out in 1u AC 100G
V1 1 0 0 AC 1
.ends simple-openloopgain1


Best regards,
Helmut

hmmm...maybe I was too quick to dismiss this
IF I use three 'different' text files, one for each analysis type, then bounce between them!
Now if there is just some way to include the the command strings:
'file'
'export'
select style of output,
overwrite, yes

is there a way to add command strings like this??

If so, you have REALLY automated this for me!


--- dwh@... wrote:

From: David Hawkins <dwh@...>
To: LTspice@...
Cc: Macy <macy@...>
Subject: Re: [LTspice] Re: Help! How do I do find maximum signal easily!
Date: Fri, 12 Jul 2013 16:07:44 -0700

[snip] and the .ac using specific values requires storing on the
schematic a list so long that it makes the schematic the size of a
postage stamp in auto size. perhaps a plus sign on the first of a few
lines will allow wordwrap - narrow width with long list.

Why not put all the relevant text into file, and then .include it.
It makes the schematic look nicer, and allows you to add
header comments to the file along with relevant comments
throughout the file.

Cheers,
Dave