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Hello everyone,

I have a problem with ac analysis of my circuit (can be found in Files > Temp > AC Analysis > TEC-Model.asc). The overall circuit consists of two separate circuits which are connected with each other by behaviourale sources. Transient analysis seems to work flawlessly as expected, however ac analysis doesn't unfortunately. My goal is to get the transfer function of this particular circuit with input being voltage (net name = V_input) and output being temperature (net name = T_h_TC).
To begin with I had tried the laborious way of manually determining the bode diagram by performing transient analysis at several frequencies (0.001 0.01 0.1 1)Hz with sinusoidal excitation. I then compared amplitudes and phases of input and output at each frequency to get the bode plots of my system. It works but the process takes up too much time...
All I want is to apply a ac sweep from 0.001 to 1 Hz on my system to see how the output responds, however, the output is steady with absolut no changes when doing so (as a matter of fact, there are no changes anywhere within the circuit). It seems as the output is not dependent on the input anymore when performing ac analysis and I was wondering for quite a while now why that is the case? I suspect that the behaviourale sources are the cause for this phenomenon as they connect input and output.
I was hoping an LTspice expert could help me with this issue?

Many thanks in advance already.

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

got 300+ emails for two days...

As few as that:-)

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

I don't know if the LTspice List has been hacked but I'm suddenly barraged with spam, like ~100 E-mails per day... sent to an address I use only for LTspice. So I changed my address. (Easy for me, I maintain ~200 different E-mail addresses just to cope with such situations :-)

Seriously I note from the Yahoo Group Managers Forum



(you can all drop by, the messages are open to any one to read)

that recent Yahoo problems whereby many folks could not post, upload photos, or add members to groups by the web interface have been have been attributed to flaws with its "defensive" software that I guess, stops among other things "spam submissions", "guessing on passwords" and "bot networks" from creating dummy ids, making multiple postings and harvesting e-mails etc.

Perhaps another side effect was that in order to fix the problems they had to lower the defenses for a while hence the bursts of spam.

Dave
G4UGM

PS If any one thinks this is a fairy story, then I'll happily discuss off list. From time to time I have to look at the fire wall logs for a small UK town council. (My employer). If we are deemed worthy of attack I can't conceive the onslaught that must be thrown at Yahoo.

In message <k1f6b3+f6lm@...>, dated Mon, 27 Aug 2012, Richard <riscy00@...> writes:

###Sorry I should make myself clear, I was referring to independent Y-axis scale of 2,3,4 type, ie one y-axis -1V to +1V and other y-axis -50V to +10V and so on. When doing noise/interference analysis, one axis show uV scale while the PSU O/P with ripple on V scale.

You can use waveform arithmetic to do that. To plot a microvolt value Vu with tens-of-volt values, click on 'Vu' at the top of the plot and enter 'Vu*1E7' in the dialogue box.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
Instead of saying that the government is doing too little, too late or too
much, too early, say they've got is exactly right, thus throwing them into
total confusion.
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

Sorry I was referring to independent Y-axis scale link to the waveform. The current arrangement is too limited.

Hi Helmut thank for the reply, it is much appericated.

One thing I found in LTSpice is the documentation, I was reading about .measure feature which is very difficult to understand them until I went to LTSpice forum which point to example which make sense this way, then I look back to document and sorry it did not work out.

My comment under ###

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

--- In LTspice@..., "Richard" <riscy00@> wrote:

I was curious if there is any prospect or plan for upgrade to,
enchance LTspice or are u being restricted by LTC company.

Hello Riscy,

LTspice is SPICE. You can use any SPICE model from any
component vendor.
Why do you think it's restricted?

### I do not say Spice is restricted but feature of the LTSPice appears to be restricted because LTC, I fear only interest in supporting their products and model.

I do not see much upgrade for some time now but it is very bug
free.

I am sure Mike will add new features in the future.

### I'm not convinced. There are several features that could be upgraded by obvious demands, but it has it not for a while. I would be nice to see what Mike plan for upgrade on LTSpice.

For example dual or 4 y axis scale for different readout.

LTspice a feature named "Plot Panes" and automatically plots
more vertical scales if you plot items with different units.
Are you aware of that?

###Sorry I should make myself clear, I was referring to independent Y-axis scale of 2,3,4 type, ie one y-axis -1V to +1V and other y-axis -50V to +10V and so on. When doing noise/interference analysis, one axis show uV scale while the PSU O/P with ripple on V scale.

Direct waveform measurement like scope.

I don't expect such features like scope measurements.

### It would be good feature in any cases, it more direct than .measure.

Wizard to implement models so we can implement generic
symbol with 3rd vendor.

Some help to create a symbol is already implemented.

### Please advise, maybe I missed that.

Customized short cuts keys

They are already implemented.

Control Panel -> Drafting Options
Control Panel -> Waveforms

### thanks.

Wizard to support measure feature.

OK, it's not implemented. I think this could be very helpful.
Maybe you or somebody will write one in the future.

I'm not employee of the LTC, and it does not support 3rd party extension implementation. Maybe it would be good thing to have for community to write their own feature.

Link to forums example library and discussion

Links to the Internet are always a problem.
I recommend to search in all_files.htm of this group.

### Okay np.

We happy to pay for premium release for DIY user.
Ie lower price than pspice.
Tux
Riscy

I prefer to have only one version, the free one.
You can pay money if you like. Somebody offers an
optimizer (49$?).

### What this?, link if you please?

If you have wishes for new features in LTspice, you should
send them to Mike, the author of LTspice. His address is
the email address given in the Help -> About.

Best regards,
Helmut

### I send this copy to mike, once again thank for forum.

I wish to thank as well to Helmut.
Does the company LT spice intends to make upgrade on LTSpice to improve useability?

got 300+ emails for two days...

I'm not getting ANY since I changed my E-mail address >:-}

Thanks for the suggestion, I will try this too.

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

Hi experts,

I am relatively new to LTspice, so I am trying to practice using it by checking a portion of the circuits from an existing design.

I connected up the circuit as listed as far as I can tell, but when I tried run it I got a "analysis timestep too small" error message.

Can someone take a look at how I wired it up and tell me what I did wrong?

Both the schematic (I only wired up the DFF portion on the top right corner) and my Spice file can be found here:



Thanks.

Tom

Tom,

The fundamental problem you have is that the propagation delay of the FF is zero. A simple solution is to add Td=5n to the value field of the FF in the Component Attribute Editor. Put your cursor over the FF and click right to get the editor. You could also specify other dynamics for the FF; see the help file on Special Functions. Also the default logic levels are 0 and 1 volt. Again, these can be changed.

Another problem is with your signal source. As specified it swings from -2.5 to 7.5 volts. Also M means milli; use meg to get mega Hz.

Rick

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

Hi experts,

I am relatively new to LTspice, so I am trying to practice using it by checking a portion of the circuits from an existing design.

I connected up the circuit as listed as far as I can tell, but when I tried run it I got a "analysis timestep too small" error message.

Can someone take a look at how I wired it up and tell me what I did wrong?

Both the schematic (I only wired up the DFF portion on the top right corner) and my Spice file can be found here:



Thanks.

Tom

Hello Tom,

Flipflops require at least a delay or a rise time, Td=5n.
I have also added an high level of 5V, Vhigh=5.
You can enter these values, if you right-mouse-click on a
flipflop.

SpiceLine:Td=5n
SpiceLine2:Vhigh=5

I have "repaired" your circuit (DFF_excercise1.asc).
All files are now in the Temp-folder.

Files > Temp > tomshong > DFF_excercise1.asc



You can learn more about the possible attributes for digital
devices from these examples.

Files > Tut > Digital A-Devices > DIGITAL_A_DEVICES_1.ASC

Files > Tut > Digital A-Devices > Initial_state_of_FF.asc



Best regards,
Helmut

Hi experts,

I am relatively new to LTspice, so I am trying to practice using it by checking a portion of the circuits from an existing design.

I connected up the circuit as listed as far as I can tell, but when I tried run it I got a "analysis timestep too small" error message.

Can someone take a look at how I wired it up and tell me what I did wrong?

Both the schematic (I only wired up the DFF portion on the top right corner) and my Spice file can be found here:



Thanks.

Tom

"WkwModels.pdf"

sawreyrw wrote:

On 8/26/2012 1:45 PM, Donald H Locker wrote:

Electronics_101 <> is
quite a suitable place to discuss such matters. We also use LTspice
(and whatever other tools are necessary or handy, up to and including
oscilloscopes and soldering irons) to achieve the understanding.

Donald.
-

In keeping with Helmut's guidance that this group is a LTspice support
group and extended electronic design discussions are discouraged I
suggest people who have electronic design questions visit
<>.

This is from the groups FAQ.

"What kind of questions can I ask here?
<>

This site is for electronics and electrical engineering professionals,
students, and enthusiasts. We ask and answer questions about electrical
and electronics engineering topics, which include electronics, physical
computing, and those working with microcontrollers, Arduinos and
embedded systems. We feel the best Electronics Design questions have a
schematic, links to pertinent datasheets or some C code in them, but if
your question generally covers …

* a specific electronics design problem
* the theory and simulation of electromagnetic forces
* a communication scheme
* the writing of firmware for bare-metal or RTOS applications

and it is not about …

* a shopping or buying recommendation
* consumer electronics such as media players, cell phones or smart
phones, except when designing these products or modifying their
electronics for other uses
* Programming software for a PC

… then you’re in the right place to ask your question!"

I believe visitors to stackExchange will find they discuss a much larger
variety of electronic design questions than the Electronics 101 mail group.


Howard

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

Great Group

Learning a lot about LTspice here. I have noticed that some symbol files use a windows designation and also get shaded or filled rectangle symbols. Like the dip 8 under misc files.

Is there any documentation about these and other drawing commands?
I using a 128K cell connection so haven't been able to do extensive searches for this info.

Thanks in advance.
Tim

Hello Tim,

Rectangles in symbols will be filled, if the symbols have the
attribute Prefix:X. The colour will be always the same(yellow).
"Prefix:X" means the symbol is for a subcircuit.

Best regards,
Helmut

You can either have quality, or quantity. It would be a shame to give up the quality this group has, especially after preserving it for such long (and, hopefully, for even longer).


Vlad

No. It should be tied directly to this one, Helmut, because the files of interest will always be here and people will surely object to a generic forum requiring LTSpice to see the principles being discussed.

Maybe we should just let the dust settle. Personally I don't think a single thing posted was any more off topic than most of the discussions around here, and if you're happy, the rest of us apparently are too... with the possible exception of Kevin himself.

How old is he? Anybody bother to ask? I wonder, because he had the collector and emitter reversed on one of his transistors but the rest of the circuit was fine. At least it was as fine as any of the other audio amps currently in our files area.


Helmut wrote:

Great Group

Learning a lot about LTspice here. I have noticed that some symbol files use a windows designation and also get shaded or filled rectangle symbols. Like the dip 8 under misc files.

Is there any documentation about these and other drawing commands?
I using a 128K cell connection so haven't been able to do extensive searches for this info.

Thanks in advance.
Tim

--- In LTspice@..., Donald H Locker <dhlocker@...> wrote:

Electronics_101 <> is quite a suitable place to discuss such matters. We also use LTspice (and whatever other tools are necessary or handy, up to and including oscilloscopes and soldering irons) to achieve the understanding.

Donald.

Hello Donald,

Thanks. That's much better than creating a new group.

Best regards,
Helmut

--
*Plain Text* email -- it's an accessibility issue
() no proprietary attachments; no html mail
/&#92; ascii ribbon campaign - <www.asciiribbon.org>

----- Original Message -----

From: "rainbowsally" <rainbowsally@...>
To: LTspice@...
Sent: Sunday, August 26, 2012 10:35:53 AM
Subject: Re: [LTspice] Re: Kevin -- Tip: a cheap full load resistor

Received and understood, Helumut.

But it would be nice to be able to have a place to discuss this kind
of
stuff. We can get resistors, caps, and transistors, etc. from vendors,
which is supported here, and in fact we have libraries full of stuff
that includes how to get these things. But no pricing info (which
likely changes all the time so it's no biggie).

What we don't have is crosses for various components that are easy to
look up (from comparisons of power, max voltage, gain where
applicable,
etc) and what if a toaster or a waffle iron ends up being a very
affordable cross for a thousand watt 4 ohm resistor.

If we make that a Spice model, would it suddenly be on topic?

I'm not trying to make problems, Helmut, it should be obvious that I'm
trying to make solutions. Sorry if this topic is aggravating to you in
this forum, but if you created a spinoff group and listed it
officially
on the main page, maybe we could share these interesting plug in
compatible, non commercial crosses and save enough money to buy a
gazillion 2n4401's (200 bucks can buy a lot of zits) from whatever
corporate vendors we have spice libraries for.

This is probably the third or fourth appeal to you on this subject of
where we might share this kind of info and you have not offered a
suggestion or a subforum (like LTSpiceFiles).

Can we compromise on this somehow? The folks here are very interesting
and helpful but keeping track of LTSpice forum members that want to
talk
off list is very inconvenient.


Helmut wrote:

--- In LTspice@..., "aurora_viii"<aurvii@> wrote:

--- In LTspice@..., Dana Myers<dana.myers@> wrote:

BTW, LCR meter applied to Sony SS-5000F speaker showed a *very*
reactive load over the audio range, likely largely influenced by
the
crossover network. At 1KHz, I saw 14.93 + j 7.851 ohms, at 5KHz
I saw 11.6 - j4.62 ohms. etc.

Cheers.

Dana K6JQ

Be very careful believing what LCR meters say, try disconnecting
the speaker drive unit and measuring that. I predict could be
several hundred uH, or at least a couple

Hello,
Please stop on these threads:

...a cheap full load resistor
...Power Supply Ripple
...audio amp...

Every further message and many of the previous posting may
be deleted soon due to be off-topic.

Best regards,
Helmut




------------------------------------

Yahoo! Groups Links

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Yahoo! Groups Links

--- In LTspice@..., "Shadow" <shadowvpr123@...> wrote:

I also tried searching for it, and you were right, it was the first one on the search list.. sorry about that.. but uhhm, how do you convert that information to a spice model?

--- In LTspice@..., John Woodgate <jmw@> wrote:

In message <k1ddm4+i2u8@>, dated Sun, 26 Aug 2012, Shadow
<shadowvpr123@> writes:

I need to simulate a circuit involving a dual npn transistor,
specifically 2N2920 transistor,.. Well I can't find a model here...
Could you help me out... Maybe i didn't search enough... Do you guys
know where i can find that transistor? or any transistor model similar
to 2N2920? Thanks..

Maybe you didn't search enough. The first hit I get from Google leads
to:



Scroll down. The model looks very basic to me, but may be enough.

Hello,

This model is only useful, if you are interested in DC or very low frequency operation, because the only daynamic parameter included is Tf. Cje, Cjc and Tr are required to get reasonable results at higher frequencies or if the transistor saturates (Tr). The LTspice help file lists the parameters for a BJT model. In many cases the defaults are ok, but the ones I listed above are required. Google for WkwMmodels.pdf for good information on device modeling. It explains how to determine device parameters from typical datasheet information.

Rick