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How much fluff would be added with a line in the help like:

SpiceLine: Vt=0.5 Vh=0.1m

When someone does not use LTspice very often (in my case, intensively 2 or 3 times a year) I cannot even remember what the delimiters are between the values. I (also do programming, professionally, and I can go, in the Language Reference, and find the syntax for the language I use).

One of the big attributes of LTspice is efficiency. Any time that you have to go to some other source (a Wiki, a Pspice manual, or such) is a hit on the productivity. This COULD be significantly improved for me by including a few examples, such as the one above, particularly where you have to provide the parameters or a model (such as SWITCH) in order to get it to work. And, for me, SWITCH is the worst of the worst because there is no default operation.

Thanks
Jim

On Jul 6, 2013, at 12:40 PM, analogspiceman wrote:

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

It would REALLY help if there were just examples in the Help.
How is it that you specify a SCHMITT or a SWITCH? It would take
very few such examples to help those of us who are not frequent
users or who do not have an encyclopedic memory.

LTspice Help is written primarily as a terse reference guide (with
a few examples thrown in). Usually all the information required
to use a feature is included, albeit in a very condensed form.
Mike has written Help like working programming code - you know all
the information must be there (since it works, at least for some),
but you must interpret each word as if you yourself were a compiler
digesting the code. This often requires many read-throughs of a
topic paying attention to the logical meaning of each word.

This works well for some and is in the spirit of a pure reference
guide akin to traditional programming language reference guides.
I know Mike does not want to bloat Help with lots of "fluff"
teaching examples so that it becomes difficult to find the "meat"
thereby degrading its usefulness as a reference.

Personally, I wish he would take out more of the random fluff from
Help, so that at the top levels it would be more of a pure LTspice
reference guide. But for each and every topic, Help should also
include several clickable hotlinks to copious examples, both text
and graphical. I don't see why it couldn't also include clickable
links to open runnable schematic example files as well.

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

--- In LTspice@..., "zeeglen" <glen@...> wrote:

Too bad this information is not easily found in the Help file.

Yes, Help, although fairly extensive, is not complete. The LTwiki
documents many of the missing items.

Since you seem willing and able, here is a big hint on how to use
LTspice itself to answer questions not answered in Help. Make sure
Generate Expanded Listings is enabled in the Control Panel. Then,
after you run a simulation with puzzling results, carefully examine
and compare the netlist (drop down menu item) and the *digested*
netlist that appears in the SPICE Error Log. That (an a little
experimentation) will inform you as to how LTspice deals with all
those SpiceLines, Values, and other such parameters.

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

It would REALLY help if there were just examples in the Help.
How is it that you specify a SCHMITT or a SWITCH? It would take
very few such examples to help those of us who are not frequent
users or who do not have an encyclopedic memory.

LTspice Help is written primarily as a terse reference guide (with
a few examples thrown in). Usually all the information required
to use a feature is included, albeit in a very condensed form.
Mike has written Help like working programming code - you know all
the information must be there (since it works, at least for some),
but you must interpret each word as if you yourself were a compiler
digesting the code. This often requires many read-throughs of a
topic paying attention to the logical meaning of each word.

This works well for some and is in the spirit of a pure reference
guide akin to traditional programming language reference guides.
I know Mike does not want to bloat Help with lots of "fluff"
teaching examples so that it becomes difficult to find the "meat"
thereby degrading its usefulness as a reference.

Personally, I wish he would take out more of the random fluff from
Help, so that at the top levels it would be more of a pure LTspice
reference guide. But for each and every topic, Help should also
include several clickable hotlinks to copious examples, both text
and graphical. I don't see why it couldn't also include clickable
links to open runnable schematic example files as well.

I have found the instance parameters and Spiceline and Spiceline2 to be totally incomprehensible. I think it assumes a familiarity with ancient_spice which Mike thoroughly refuses to detail in the Help File. At that point, I usually flounder and try, sort of pseudorandomly, until something appears to work.

It would REALLY help if there were just examples in the Help. How is it that you specify a SCHMITT or a SWITCH? It would take very few such examples to help those of us who are not frequent users or who do not have an encyclopedic memory.

That said, SCHMITT is like an inverter with input hysteresis defined. I don't remember the details but I think that you specify either the high and low trip points OR the hysteresis amplitude and the midpoint of the hysteresis window, or something like that. And, yes, you have to do it in a spiceline. Please don't ask me how!

Jim Wagner
Oregon Research Electronics

On Jul 6, 2013, at 11:18 AM, zeeglen wrote:

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

--- In LTspice@..., "zeeglen" <glen@> wrote:

Can anyone explain why the difference between INV and SCHMITT?

Try reading the Help file next time before spamming the group with
your needlessly ignorant drivel. Quoting Help:

Actually, the Help file was the first place I went hunting and found this:

The Schmitt trigger devices have similar output characteristics as
the gates. Their trip points are specified with instance parameters
Vt and Vh. The low trip point is Vt-Vh and the high trip point is
Vt+Vh.

At that point I searched for "instance parameters", and one of the several pages I investigated was titled "Adding Attributes". That led to "General Attribute Editor" which displays a "Component Attribute Editor". Nowhere does it state what is meant by "Spiceline" or "Spiceline2".

That is when, as I described, I tried driving both INV and SCHMITT from the same sine wave voltage source and noted their switching voltage was identical. If so, why the difference in the circuit? That was my question.

I have since found more information online that actually clearly states how to input instance parameters using the Spiceline in the Component Attribute Editor. Too bad this information is not easily found in the Help file. Do not assume that those who come to this forum seeking assistance have not already attempted to find the answer. The reason they come to this forum is that have tried but not been able to find the answer.

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

--- In LTspice@..., "zeeglen" <glen@...> wrote:

Hi all. I've just uploaded a file "Monostable VCO Schmitt problem.asc". The simulation works when a INV is used, but has problems when a SCHMITT inverter is used instead. Both use default values, and as far as I can tell they are identical other than the SCHMITT is about 4 usec more delay. The SCHMITT has no visible hysteresis when driven from a sine source.

V2 on the far left is the VCO control voltage. Up top there is a choice between INV A1 and SCHMITT A2. As long as INV A1 is in the circuit it oscillates with V2 as low as 0 volt. But if A1 is disconnected and SCHMITT A2 connected in its place the circuit does not oscillate when V2 is below 1 volt. The falling ramp from opamp U2 appears to get too small to cross an assumed lower trip point, yet there doesn't seem to be any difference between trip points; I have not changed Vt and Vh from the SCHMITT default values (not sure how).

I am trying to replicate the Schmitt action of the trigger input of a 74HC221 monostable with the LTC6993-1 and the INV along with Q1. R10 and R11 are there to divide the opamp U2 output by 5 to switch at the A1 A2 threshold of 0.5 volt when U2 is 2.5 volt.

Can anyone explain why the difference between INV and SCHMITT? Maybe I do need to set a value of 0 for Vh. Also tried SCHMTINV (A3), it has the same problem

Thanks in advance.

Hello,

I just tried your example.

Right-mouse-click on the Schmitt-inverter.

SpiceLine: Vt=0.5 Vh=0.1m

I remember a case where I additionally needed a small delay.

SpiceLine: Vt=0.5 Vh=0.1m Td=10n


Best regards,
Helmut

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

--- In LTspice@..., "zeeglen" <glen@> wrote:

Can anyone explain why the difference between INV and SCHMITT?

Try reading the Help file next time before spamming the group with
your needlessly ignorant drivel. Quoting Help:

Actually, the Help file was the first place I went hunting and found this:

The Schmitt trigger devices have similar output characteristics as
the gates. Their trip points are specified with instance parameters
Vt and Vh. The low trip point is Vt-Vh and the high trip point is
Vt+Vh.

At that point I searched for "instance parameters", and one of the several pages I investigated was titled "Adding Attributes". That led to "General Attribute Editor" which displays a "Component Attribute Editor". Nowhere does it state what is meant by "Spiceline" or "Spiceline2".

That is when, as I described, I tried driving both INV and SCHMITT from the same sine wave voltage source and noted their switching voltage was identical. If so, why the difference in the circuit? That was my question.

I have since found more information online that actually clearly states how to input instance parameters using the Spiceline in the Component Attribute Editor. Too bad this information is not easily found in the Help file. Do not assume that those who come to this forum seeking assistance have not already attempted to find the answer. The reason they come to this forum is that have tried but not been able to find the answer.

--- In LTspice@..., Jim Thompson "jtanalog" wrote:

Is there any way, in a LTspice plot, to _display_ the average
of a waveform over a specified interval? Something like the
AVGX mechanism in PSpice's Probe?

Mike Engelhardt has stated that he is philosophically opposed to
such imprecise functions. What is average? Is it an analog low
pass filter function or a numerical sliding average? What order
is it and what is its corner frequency/period? Is it a fixed
percentage of the total simulation run time or perhaps some
percentage the time interval as currently displayed within the
Waveform viewer (thus changing every time the zoom level is
changed)?

Average and Integrate would be very useful visualization tools for
to help analyze data after a simulation completes (right now, if
you don't plan ahead, you must rerun after adding those functions
within the schematic), but in order to be acceptable to Mike, they
would have to be much more precisely defined (perhaps via multiple,
optional parameters) than the Pspice versions.

The LTspice waveform viewer does not currently offer a "running
average" function (it only makes available a single numeric average
for the entire data set displayed in the currently visible window).
I don't see any technical reason why the waveform viewer shouldn't
be able to generate a running average, but Mike Engelhardt seems
to think that an auto adjusting running average would be too ill
defined (dependent on window span and an arbitrary averaging
function) and therefore misleading or at best a poor general
purpose compromise to what is actually needed in a vast variety
of individual circumstances (personally, I think that Mike may
be overlooking that the value of a running average would be
more qualitative than quantitative - it would be primarily a
visualization aid).

If you really must have a running average, you could always add
into the simulation a simple low pass circuit to the signal of
interest to calculate a running average of the appropriate time
constant for your visualization needs. You would then click on
the LP output to see the running average in the waveform viewer
(of course, this requires you to set it up ahead of time or to go
back, add the LP and rerun the simulation - not very user friendly).

As a compromise, perhaps Mike could be persuaded to add the ability
to the waveform viewer (via a new waveform math function) to access
"time delayed" data points (along with the delta delay time value)
by a specified number of samples or, alternatively, access time
delayed data by a specified delay time. Then the user could make
up his own customized running average function using waveform math.

Waveform math already includes a derivative function, d(). If Mike
were to add an integrate function, something like s(x[,ic[,a]])
defined as integrate x, optional initial condition ic, reset if a
is true, then you could define a user function to build your own
"boxcar" style running average (using the built-in variable "time"
and the modulus function operator "%").

--- In LTspice@..., "jtanalog" <ltlist@...> wrote:

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

--- In LTspice@..., "jtanalog" <ltlist@> wrote:

Is there any way, in a LTspice plot, to _display_ the average of a waveform over a specified interval? Something like the AVGX mechanism in PSpice's Probe?

-Jim Thompson

Hello Jim.

Unfortunately it's not possible to directly define a formula
with integration in the waveform viewer. One has to make a
Bv-source in the schematic or netlist.

.param d=100u
.func avgx(x,d) {(idt(x)-delay(idt(x),d))/d}

BV1 avgout 0 V=avgx(V(out),d)

BV2 avg37 0 V=avgx(V(37),d)

By the way you don't need a Bv-symbol. You could directly add
these SPICE-lines from above to your schematic. You will need
one B-device SPICE-line for every item you want to average.

I tried an example and found it's necessary to define a small
max time step in .TRAN and to switch off data compression for
best results.

.options plotwinsize=0 ; data compression off

The text after ';' is only comment.

Best regards,
Helmut

Thanks, Helmut! That's what I was looking for.

Is it possible to define your own set of functions (maybe in a library somewhere) that can be used later?

(I still haven't found the VDMOS tool. Can you give me a link?)

-Jim Thompson

Hello Jim,

Only plot-formulas could be in a central file managed by LTspice,
but this is dangerous when you over-install LTspice intentionally
or by accident or when you move to another PC and have forgotten
it.You could have your functions in your own file and .lib it to
your schematic.

The VDMOS-tools you asked for is in the folder Software.

Files > Util > Files > Util > Model Tools > Board Level MOSFET (VDmos)> Software




Another program is this one.

Files > Util > vdmos171.zip




Both programs will still require hand tuning.

Best regards,
Helmut

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

--- In LTspice@..., "jtanalog" <ltlist@> wrote:

Is there any way, in a LTspice plot, to _display_ the average of a waveform over a specified interval? Something like the AVGX mechanism in PSpice's Probe?

-Jim Thompson

Hello Jim.

Unfortunately it's not possible to directly define a formula
with integration in the waveform viewer. One has to make a
Bv-source in the schematic or netlist.

.param d=100u
.func avgx(x,d) {(idt(x)-delay(idt(x),d))/d}

BV1 avgout 0 V=avgx(V(out),d)

BV2 avg37 0 V=avgx(V(37),d)

By the way you don't need a Bv-symbol. You could directly add
these SPICE-lines from above to your schematic. You will need
one B-device SPICE-line for every item you want to average.

I tried an example and found it's necessary to define a small
max time step in .TRAN and to switch off data compression for
best results.

.options plotwinsize=0 ; data compression off

The text after ';' is only comment.

Best regards,
Helmut

Thanks, Helmut! That's what I was looking for.

Is it possible to define your own set of functions (maybe in a library somewhere) that can be used later?

(I still haven't found the VDMOS tool. Can you give me a link?)

-Jim Thompson

--- In LTspice@..., "zeeglen" <glen@...> wrote:

Can anyone explain why the difference between INV and SCHMITT?

Try reading the Help file next time before spamming the group with
your needlessly ignorant drivel. Quoting Help:
________________________________________________________

The gates default to 0V/1V logic with a logic threshold of .5V,
no propagation delay, and a 1Ohm output impedance. Output
characteristics are set with these instance parameters:

Name Default Description
------------------------------
Vhigh |. 1 .| Logic high level
Vlow .|. 0 .| Logic low level
Trise |. 0 .| Rise time
Tfall |Trise| Fall time
Tau . |. 0 .| Output RC time constant
Cout .|. 0 .| Output capacitance
Rout .|. 1 .| Output impedance
Rhigh |Rout | Logic high level impedance
Rlow .|Rout | Logic low level impedance

Note that not all parameters can be specified on the same instance
at the same time, e.g., the output characteristics are either a
slewing rise time or an RC time constant, not both.

The propagation delay defaults to zero and is set with instance
parameter Td. Input hold time is equal to the propagation delay.

The input logic threshold defaults to .5*(Vhigh+Vlow) but can be
set with the instance parameter Ref. The hold time is equal to the
propagation delay.

The Schmitt trigger devices have similar output characteristics as
the gates. Their trip points are specified with instance parameters
Vt and Vh. The low trip point is Vt-Vh and the high trip point is
Vt+Vh.

The gates and Schmitt trigger devices supply no timestep information
to the simulation engine by default. That is, they don't look when
they are about to change state and make sure there's a timestep close
to either side of the state change. The instance parameter tripdt
can be set to stipulate a maximum timestep size the simulator takes
across state changes.

--- In LTspice@..., "jtanalog" <ltlist@...> wrote:

Is there any way, in a LTspice plot, to _display_ the average of a waveform over a specified interval? Something like the AVGX mechanism in PSpice's Probe?

-Jim Thompson

Hello Jim.

Unfortunately it's not possible to directly define a formula
with integration in the waveform viewer. One has to make a
Bv-source in the schematic or netlist.

.param d=100u
.func avgx(x,d) {(idt(x)-delay(idt(x),d))/d}

BV1 avgout 0 V=avgx(V(out),d)

BV2 avg37 0 V=avgx(V(37),d)

By the way you don't need a Bv-symbol. You could directly add
these SPICE-lines from above to your schematic. You will need
one B-device SPICE-line for every item you want to average.

I tried an example and found it's necessary to define a small
max time step in .TRAN and to switch off data compression for
best results.

.options plotwinsize=0 ; data compression off

The text after ';' is only comment.

Best regards,
Helmut

Hi all. I've just uploaded a file "Monostable VCO Schmitt problem.asc". The simulation works when a INV is used, but has problems when a SCHMITT inverter is used instead. Both use default values, and as far as I can tell they are identical other than the SCHMITT is about 4 usec more delay. The SCHMITT has no visible hysteresis when driven from a sine source.

V2 on the far left is the VCO control voltage. Up top there is a choice between INV A1 and SCHMITT A2. As long as INV A1 is in the circuit it oscillates with V2 as low as 0 volt. But if A1 is disconnected and SCHMITT A2 connected in its place the circuit does not oscillate when V2 is below 1 volt. The falling ramp from opamp U2 appears to get too small to cross an assumed lower trip point, yet there doesn't seem to be any difference between trip points; I have not changed Vt and Vh from the SCHMITT default values (not sure how).

I am trying to replicate the Schmitt action of the trigger input of a 74HC221 monostable with the LTC6993-1 and the INV along with Q1. R10 and R11 are there to divide the opamp U2 output by 5 to switch at the A1 A2 threshold of 0.5 volt when U2 is 2.5 volt.

Can anyone explain why the difference between INV and SCHMITT? Maybe I do need to set a value of 0 for Vh. Also tried SCHMTINV (A3), it has the same problem

Thanks in advance.

--- In LTspice@..., "jtanalog" <ltlist@...> wrote:

Is there any way, in a LTspice plot, to _display_ the average of a waveform over a specified interval? Something like the AVGX mechanism in PSpice's Probe?

-Jim Thompson

Jim,

I'm surprised you haven't looked at the LTspice help file. This is in the help under Waveform Viewer>Waveform Arithmetic.

Rick

Is there any way, in a LTspice plot, to _display_ the average of a waveform over a specified interval? Something like the AVGX mechanism in PSpice's Probe?

-Jim Thompson

Hello Jesper,

However, to be honest I still don't understand/know how the
"complete" import of a component with a different pin layout
and/or a new symbol is done.

My examples are for a universal symbol and a specific symbol.
Please open the symbol files(.asy) with the symbol editor of
LTspice and view the obvious differences in the attributes of
both symbols.

Edit -> Attributes -> Edit Attributes


The netlist order in the pins start from 1 and ends with the
number of pins of the subcircuit definition. The netlist order
will be from 1 to 5 for a .subckt with 5 pins.

Best regards,
Helmut

mario.chillemi wrote:

I update my version of multistage inverter in Ac analysis. Can you tell me if
it's okay with gain and V2-V3 value?

Most often, people set the AC source amplitude to 1V. With your
differential source, I'd use 0.5V for each of the two sources, to get
1V differential input voltage.

The reason is that it makes it easier to see the voltage gain. Gain =
Vout/Vin, and when Vin=1, Gain = Vout. So looking at the plot of
Vout, it IS the voltage gain too.

AC analysis is a "small-signal" linear (linearized) analysis, which
means signal amplitudes don't actually matter. You could drive it
with an AC amplitude of 100V and the analysis would be the same as if
you had used 1uV.

I suppose you might want to play with the DC offset voltage a bit (the
DC voltage of V2), to see what effect it has on AC gain.

Regards,
Andy

I went looking on the eagle forums for answers on this too only to find that it looks like the eagle forums are no longer there.

what link are you using to get to the eagle forums now ? even if unanswered ?

thanks,
boB

Hi again Helmut,

& thanks for uploading the new files :-) Incidentally, you've actually helped me with a challenge I've had on how to make a tiny circuitry to measure HF noise in DAC/ADC supply rails: With a few modifications it looks as if the circuitry you've drawn up can be used for this ... Thank you!

However, to be honest I still don't understand/know how the "complete" import of a component with a different pin layout and/or a new symbol is done. Might you be able to point me to a description of this - maybe here in this forum - that describes this for a sort of newbie, i.e. in an intuitive way and maybe step by step? I've been using LTSpice for some years now and know how to perform some setups and analyses but sometimes still need to take things step by step.

Also, I am looking for an LTspice/spice model of one of those lamps that are used in oscillator designs to adjust the AGC of the feedback loop. I've searched the files here and found some but am unsure which one to use. I'm considering building an oscillator similar to the one shown in the LT1007 spec sheet (ultrapure sinewave oscillator):



but at a higher frequency (1 - 10 MHz if possible). Would you off the bat know which of the lamp files to use?



Once again, thanks for your previous help, Helmut. And BTW if the simulations LMH6629 simulations are realistic it looks as if it's a quite well-designed component - not easy to make unstable. Impressive actually ...

Greetings,

Jesper

Basier philippe <basier.philippe@...> wrote:

Should I have to understand you have still problems with opening all_files.htm ?

Yes. The problem has not gone away.

I am seeing similar problems with many other Yahoo!groups too.
Ordinary text files and HTML files that used to open when clicked on,
now can only be downloaded.

Regards,
Andy

Some background, not intended to be criticism, then the question.

Cadsoftusa's Eagle 6.4 introduced an interface to link schematics with LTSpice IV for simulation. Unfortunately, the link does not seem to be fully functional. There is no documentation from Cadsoftusa about this link that I have been able to find. Cadsoftusa's website points to Newark (Element 14) for technical support. Newark (Element 14) has a number of Eagle Webcasts but these have provided limited help. Also, their forum questions go un-answered. In fairness, Newark (Element 14) is in the business of selling, not providing implementation details of a product; they do provide LTSPice IV models and Eagle symbols and placement data for many components.

I have been able to create a link Eagle 6.4 to LTSpice IV but have not been able to transfer a schematic for simulation.


Separately, I have been able to download spice models and symbols and integrate them into LTSpice IV for simulation.

Separately, I have been able to download and integrate schematic symbols and placement data into Eagle 6.4.

Getting the two products to work an play together seem to be problematic.

The Question: Has anyone in the forum had any experience with using the Eagle 6.4 link to LTSpice IV and can provide any guidance or point to potential information.

Using a link like this seems to be a good idea and I would like to take advantage of it. I'll keep trying different things as time permits.