Alan wrote, "... they do have other parameter sets, h or y, ?and that requires conversion to S."

I think you meant to write "and that allows conversion to S."

I think Tony is still interested in the s-parameter data for the 2N3904.? Do you have a pointer to it?? Maybe when you wrote that you "gather" the s-parameters, you were speaking hypothetically?

Andy

On 23/02/2021 15:35, Andy I wrote:

For better or worse, it looks like plotting waveforms with @1 or @2 doesn't work right, but selecting them from the View > Select Steps menu does. Changing the plotwinsize option to make the timesteps smaller helps minimize the appearance of the problem, but it does not actually fix it.

It's strange, I use the @1, @2, etc. notation all the time and I very rarely see artefacts. It's essential when you need to use this feature in waveform arithmetic.

--
Regards,
Tony

While many devices do not have S, they do have other parameter sets, h or y, ?and that requires conversion to S. Finally direct measure of S may be required.?For the case of the 3904, either measure the S directly or use h parameters and convert to S. Some y parameters exist for the 3904 as well and the same process, conversion to S is required. At that point, ?with an available non linear model, the comparison to measured as well converted to S data is needed before one can trust a non linear model.?

Instances exist where no model is available, either linear or non linear. Then measured data is required. Stated previously, beginning with S measured data does provide a gateway to a reasonable first pass approach to a non linear design. ?

Regards,?
Alan?

Vlad wrote, "flat() and gauss() are also affected by the clock seed."

Thanks.? I remember experimenting with it to see if they were also affected, but that was a long time ago.

Andy

Hello Andy

Among the six, I think only mc() can be controlled by the
system clock to make it non-deterministic (if you change that setting in the
Control Panel).

flat() and gauss() are also affected by the clock seed. It has been so
since LTspice IV.

--
Vlad
______________________
ltspicegoodies.ltwiki.org v2:
quite universal analog/digital filter,
power electronics, signal processing,
easy to work with math functions,
digital models, and rants.

Michael,

You can't send messages with attachments.

Try again without the attached files or pictures.

Andy

For better or worse, it looks like plotting waveforms with @1 or @2 doesn't work right, but selecting them from the View > Select Steps menu does.? Changing the plotwinsize option to make the timesteps smaller helps minimize the appearance of the problem, but it does not actually fix it.

Andy

Tony wrote, "You actually have two accounts with?[email protected]."

Actually, Michael, you might have three.? There's the Yahoo email address, a Preh.de address, and a Micron address which might be yours too (but I can't be sure).

It's not unusual for people here to subscribe themselves multiple times from different addresses, and then they can't figure out why changes to one of them do not affect the other(s).? This gets even more confusing if you have your emails forward from one address to another.? Make sure to use the right address when making changes.? Groups.io treats every address as distinct.? Look near the end of every message from Groups.io because it tells you what address you are subscribed from.

It looks like you unsubscribed yourself from one address in December, then re-subscribed in January and made several more changes.? Then this month you made more changes again.? All these changes were made from the web by someone (presumably you) who was logged into your Groups.io account.? When making any changes, make sure to click the correct button!? ?If you don't click the Save button at the bottom, changes you thought you made won't be saved.??If you select Daily Summary or Individual Messages and then click the wrong button at the bottom, you might unsubscribe yourself.? If you use your keyboard's up/down arrow keys, note that they might change which round buttons you have already clicked, so double-check those before clicking Save.

Groups.io only uses English (I think) for its menus, so get someone to help you if your English is not good.? I have found that it always does exactly what you tell it to do, if you remember to click the Save button.? If you can't get it to do what you want, then you probably did not do that.??You have unsubscribed yourself six times so far.? That doesn't happen unless you asked to do that!? You changed yourself to the daily digest in January, and again earlier today after you sent this message.

? ? "Can you help?"

We can help; but we can't stop you from "shooting yourself in the foot".? It looks as if you keep doing that over and over.

If you have further problems, send an email to the LTspice+owner address (shown on the group's main webpage).

Andy

? ? "Don't forget that there is a Control Panel setting to randomise the mc() function by using the system clock to seed the generator."

That's right.

LTspice has six different random functions.? Rand(), random(), and white() can be used with B-sources to generate noisy signals in transient simulations.? They are unaffected by the system clock and are always deterministic when used with the same arguments.? Flat(), gauss(), and mc() can be used with .PARAM assignments.? This means they can't change during a .tran simulation.??Among the six, I think only mc() can be controlled by the system clock to make it non-deterministic (if you change that setting in the Control Panel).

The trick here is that you can use a randomized mc() function to alter the argument of a rand(), random(), or white() function, and then make your noisy B-source generate different noise every time you run the simulation -- if that is something you really need.? I don't see a need for it, but maybe you do.

Andy

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On 23/02/2021 13:26, Kerim via groups.io wrote:

I uploaded a simple circuit of multi vibrator (NE555-v1.zip).
It seems that V(clk)@1 (or @2) is plotted as 2 traces instead of one. I am just curious why this is the case.

This will largely eliminate the issue:

.options plotwinsize=0

If a residue of the issue remains, add a sensible maximum timestep:

.tran 0 200u 140u 10n

This was discussed some weeks (or months) ago. It seems to be related to waveform compression and the timesteps on each of the stepped traces not being the same.

-- 
Regards,
Tony

I uploaded a simple circuit of multi vibrator (NE555-v1.zip).
It seems that V(clk)@1 (or @2) is plotted as 2 traces instead of one. I am just curious why this is the case.

Thanks,
Kerim

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On 23/02/2021 11:14, haubmi1 via groups.io wrote:

I have a problem with this groups.io thing!
I always received all messages to my business email account.
For some time this?mysteriously changed and I only receive a daily digest.
This is bad, as I always tried to learn something new?from some mails I find interesting by scan through it's text.
So yesterday I changed my subscription back to "Individual Messages".
Today I received following mail:

Hello,

You have been unsubscribed from [email protected]. You will receive no more emails from that group. If this was a mistake, you can resume your subscription within the next 7 days by clicking the following link:

Resume Subscription

Cheers,
The Groups.io Team

I'm fed up with this groups.io thing.
Can you help?

It doesn't look like you set it back to "Individual Messages" - it was still set to digest.

I have set it to "Individual Messages". I hope that works out OK.

You actually have two accounts with [email protected]. Your original membership of the Yahoo! group remains with your yahoo.com email address - it's not been used since being automatically transferred to groups.io in 2019. This is currently set to "no email".

-- 
Regards,
Tony

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On 23/02/2021 11:14, haubmi1 via groups.io wrote:

I have a problem with this groups.io thing!
I always received all messages to my business email account.
For some time this?mysteriously changed and I only receive a daily digest.
This is bad, as I always tried to learn something new?from some mails I find interesting by scan through it's text.
So yesterday I changed my subscription back to "Individual Messages".
Today I received following mail:

Hello,

You have been unsubscribed from [email protected]. You will receive no more emails from that group. If this was a mistake, you can resume your subscription within the next 7 days by clicking the following link:

Resume Subscription

Cheers,
The Groups.io Team

I'm fed up with this groups.io thing.
Can you help?

It doesn't look like you set it back to "Individual Messages" - it was still set to digest.

I have set it to "Individual Messages". I hope that works out OK.

-- 
Regards,
Tony

Hello,

I have a problem with this groups.io thing!
I always received all messages to my business email account.
For some time this?mysteriously changed and I only receive a daily digest.
This is bad, as I always tried to learn something new?from some mails I find interesting by scan through it's text.
So yesterday I changed my subscription back to "Individual Messages".
Today I received following mail:

Hello,

You have been unsubscribed from [email protected]. You will receive no more emails from that group. If this was a mistake, you can resume your subscription within the next 7 days by clicking the following link:

Resume Subscription

Cheers,
The Groups.io Team

I'm fed up with this groups.io thing.
Can you help?

Greetings Michael

Hello Neil

That's what I was trying to achieve, perfect.

I'm glad it worked out for you, but there's no need to open up new
threads just to thank someone. Editing the title counts as a new
thread. Please do not rename the threads, there's no need to add
"solved".

Besides, there wasn't only one person replying, which means more than
one person helped, so thanking only one is dismissing the others'
contributions. So if you're going to say "thank you all", do so in the
same, unaltered thread. You're welcome, BTW.

--
Vlad
______________________
ltspicegoodies.ltwiki.org v2:
quite universal analog/digital filter,
power electronics, signal processing,
easy to work with math functions,
digital models, and rants.

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Vlad,

That's what I was trying to achieve, perfect.

Many thanks

Neil

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On 23/02/2021 02:24, alan victor wrote:

I am afraid you missed my point. First, I never said I would use s parameters to emulate a non linear aspect of the model. However, the point of the validation exercise is to satisfy the criteria that the s parameters of the non linear model... Spice model... operating in a linear manner meet the s parameters of the measured device. Many of them do... spot on. And other models fail miserably.

While we're missing points, you forgot to point to where S-parameters for the 2N3904 can be found. Of the thousands of different types of transistors in existence, probably fewer than 1% of them have published S-parameters.

Second point, the use of s parameters actually can produce a very excellent STARTING point for successful non linear design. I have applied such techniques to both power amplifiers and one and two port oscillators.

I agree about a starting point in the absence of non-linear parameters. But since these designs can only really be optimised by non-linear analysis, you need the non-linear parameters anyway - S-parameter analysis provides no information relating to how much power you're going to get, for example. Having said that, the great advantage of design by S-parameters is that linear analysis is orders of magnitude faster than non-linear analysis.

Again, I emphasize they provide an excellent initialized starting condition. That is to say, ?find embedding networks, matching elements and resonator development in oscillator applications.

-- 
Regards,
Tony

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On 23/02/2021 06:36, Andy I wrote:

WHS wrote, "There were reports at one time that 2 or more rand() functions were random but very well correlated with each other. Has this been corrected?"

What is there to correct?

The rand() function is a deterministic function.? That is by design.? You give it an argument, and it converts it to a semi-random result.? It is not a random-sequence generator, like a linear-feedback-shift-register.? No, not like that.? Given the same argument x, rand(x) always returns the same result, every time.? That's how it should work, and that's how it does work.

The way to use two rand() functions in the same simulation and have them different, is to assure that their arguments are significantly different.? For example, use rand(time) and rand(-time).? Or rand(time+1e6).? Or rand(time*1e6).? Or something else.? Use your head to choose something that is different for each function's argument.

As another simple example, if one rand() function uses argument values between 1.0 and 1e9, make the second rand()'s argument go from 1e9 to 2e9.? Now the two functions generate a different sequence of semi-random values.

Don't forget that there is a Control Panel setting to randomise the mc() function by using the system clock to seed the generator. This is a sticky setting, so it stays set or unset until you change it.

Control Panel > Hacks! > "Use the clock to reseed..."

-- 
Regards,
Tony

WHS wrote, "There were reports at one time that 2 or more rand() functions were random but very well correlated with each other. Has this been corrected?"

What is there to correct?

The rand() function is a deterministic function.? That is by design.? You give it an argument, and it converts it to a semi-random result.? It is not a random-sequence generator, like a linear-feedback-shift-register.? No, not like that.? Given the same argument x, rand(x) always returns the same result, every time.? That's how it should work, and that's how it does work.

The way to use two rand() functions in the same simulation and have them different, is to assure that their arguments are significantly different.? For example, use rand(time) and rand(-time).? Or rand(time+1e6).? Or rand(time*1e6).? Or something else.? Use your head to choose something that is different for each function's argument.

As another simple example, if one rand() function uses argument values between 1.0 and 1e9, make the second rand()'s argument go from 1e9 to 2e9.? Now the two functions generate a different sequence of semi-random values.

Andy