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How do you measure frequency of an oscillator accurately in LTspice..( I probably need this for .disto to work well)
cheers
AG

Hiya Heinz

I am sorry but I have to disagree.

My approach is to have the databases loaded with all the possible parts that
I may use. The only time that I hand draw a circuit diagrams now, is on a
bus, train or aeroplane, when I do not have my lap top with me. If I need to
copy an existing circuit diagrams, I am as likely to photograph it with my
mobile phone and transfer it to my computer net.

I find that Ltspice is an excellent tool creating circuits and then refining
them.

I have just done a proper check and my diodes database has grown to 279
entries including some 150 Zener diodes selecting the right one is quite a
drag. The power rating is not immediately visible and very little clues when
using one from the 1nxxxx ranges

The same can be said for varactors. I have some 50 of them in the database.
Do you keep the specs in your head? I most certainly don't.

It's just a different way of working that's all.

I also do MYSQL, PHP, C and C++ programming so I am very well aware of how
dialogue boxes work in windows, both plain vanilla and MFC. I did clone
dbaseII in C so that C programs could access and manipulate dbase files. (I
have a pathological hatred of proprietary data formats. Q what happens if
the company goes bust. A. The data becomes useless.)

I was not asking for a parametric search. A much more simple approach

Presumably the dialogue box reads the database on creation, extracts the
data that it can display and shrinks the whitespaces of the text based
model, into an array of structures. Then displays it.

Adding a select box for type would not add that much complexity. Plus it
would allow the space where type was displayed to be replaced with say power
rating or varactor capacitance or whatever.

Adding a simple filter using partial entry name is not that major either.
It's just a matter of creating a secondary array that matches the filter
term then displaying that. Thankfully C and C++ both have case less
comparison functions.

So selecting Zener in the select box and 1n in the filter would display all
the 1n series zener diodes plus a bit more of their spec


Best regards

Suusi Malcolm-Brown

PP Mike please don't think that I am trying to teach you how to suck eggs.

Hi,
thanks so much for helping me solving the problem.. But both solution
(adding Roff and changing the ground position) are giving different results.
So I wonder which one should I use.

Also Tony, can you please explain to me what's actually Roff do in the
diode?

Thanks so much everyone..

Kind regards,
Micheline

On Tue, Sep 20, 2011 at 9:46 AM, Ian <iw1904@...> wrote:

**


Hi,

The GND is in the wrong place.

Please see corrected circuit in TEMP folder

Regards

_____

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SPAMfighter has removed 3438 of my spam emails to date.

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

Hi,



The GND is in the wrong place.

Please see corrected circuit in TEMP folder



Regards


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I didn't know Helmut was Italian! Thanks.

--- In LTspice@..., John Fields <jbfields3@...> wrote:

Helmut bottom posts, and it's his group.

In Rome, shouldn't we do what the Romans do?

--
JF

Some clients make it very hard to bottom post. Others make it hard to
top-post. Some make it hard to do one for html and the other for non-html.
Please don't assume that every one else's e-mail client works just like
yours.

Sorry, bottom posting simply will not work for everyone.

Jim Wagner
Oregon Research Electronics

On Fri, 16 Sep 2011 19:12:35 +0100, you wrote:

In message <j500ob+lpdp@...>, dated Fri, 16 Sep 2011,
analogspiceman <analogspiceman@...> writes:

Well, people keeping complaining about Help, but so far no one,
including the complainers, has been willing or able to offer any
concrete constructive criticism. It remains a puzzle. -- a.s.

It needs a complete re-write, but the necessary combination of skills is
extremely rare - a way to put over intricate concepts in simple language
AND a deep understanding of LTspice. I have had some success in the
first, but I am nowhere in the second.

To do the first, you have initially to forget all you know about the
product, program or application and consider ONLY what questions the
user is likely to ask. For each question, you then 'switch on' ONLY that
part of your product knowledge needed to answer the question. If you
feel compelled to add more, formulate another question to introduce the
addition.

Hundreds of questions are likely to be required. The limited lists of up
to 20 or so, offered by Microsoft and other Helps, are pitifully
inadequate. Answers should include examples wherever possible.

---
Indeed.

But, in all fairness, earlier Microsoft stuff, like their 80XXX
assembler, Qbasic compiler, and BASIC interpreter provided excellent
documentation and, samples of code.

---
In the case of LTspice, however, since the software's free, one can't
(or shouldn't) expect the authors to jump at anyone's beck and call.

--
JF

I didn't know Helmut was Italian! Thanks.

Helmut bottom posts, and it's his group.

In Rome, shouldn't we do what the Romans do?

--
JF

Ok, that was a good thing to learn...

Thanks everyone!

/Johan

--- In LTspice@..., "Suusi M-B" <smalcolmbrown@...> wrote:

Now that I have well over 100 different diode types in Ltspice I think that something that I would find useful would be a selector box for diode type "All, Germanium, Silicon, ZENER, SCHOTTKY, VARACTOR, LED" above the select window.

LTspice is not intended as a parametric search for all possible diodes. You setup your schematic, choose the approriate parts and put them into LTspice. LTspice is only for simulating an existent schematic.

BTW: when you open "pick new diode" click on e.g. "type" in the header. The colum will be sortet alphabetically: first all germanium, following LED, then ... up to type Zener .. :-)

hws

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

In message <j57d86+fkkg@...>, Charly Engineering
<charly020664@...> writes

my LTspice-version has problems with that circuit :-)

You need to .lib arachnid.mod, which you can download from the Web.
--
This is my travelling signature, adding no superfluous mass.
John M Woodgate

Thanx John, I will spend the rest of this day with searching the lib .lib ararchnid.mod.

I think the best is to search in www3.

best regards ...

--- In LTspice@..., "Tony Casey" <tony@...> wrote:

You might investigate whether GaN FETs would do the job for you. Check out:


.. for example.

Regards,
Tony

Yes, GaN FETs are perhaps godd for that. I've thought about that. They are good, if they have a large input resistance and low input capacity.

I will check that.

best regards ...

--- In LTspice@..., "Tony Casey" <tony@...> wrote:

<snip>

Hi Tony and others,
Three more questions:
1) If prefix for an nmos.asy symbol is stated as MN, what does that mean?
2) Could you also try to explain what an intrinsic model is, I don't think I exactly understand that?
3) Is it possible to place a model elsewhere than under the &#92;lib&#92;sub folder or schematic folder besides from an website?

Regards
Carsten

</snip>
Hello Carsten,

1. The MN prefix tells SPICE that the device is an N-channel MOSFET.
2. An intrinsic device is a fancy name for a circuit element that is built in to the SPICE code. Please read the LTspice>Circuit Elements section of the Help for a complete list.
3. It is frequently recommended to avoid placing any user files in any part of installation tree, particularly if you expect to have to share simulation files with co-workers etc (it may also be overwritten in an update if Mike introduces a file of the same name - unlikely, but possible). This is because you cannot everyone else will have the same files there; you should only assume they will have the installation defaults. The advice is therefore to place any user files (.models, subcircuits, .meas scripts) in the folder containing the top level schematic. LTspice will always find them there. In principle, you can place a model anywhere if you provide an absolute path to the file in the .inc statement, but it's asking for trouble. Nevertheless, people continue to ignore the advice.

Regards,
Tony

Hi Tony,
Thank you for your fine and quick answer. I don't have any further questions, I think I understand :-).
Regards
Carsten

In message <j57d86+fkkg@...>, Charly Engineering <charly020664@...> writes

my LTspice-version has problems with that circuit :-)

You need to .lib arachnid.mod, which you can download from the Web.
--
This is my travelling signature, adding no superfluous mass.
John M Woodgate

--- In LTspice@..., "Charly Engineering" <charly020664@...> wrote:

Hi folks,

my LTspice-version has problems with that circuit :-)

help!

best regards Leo ...

Hello Leo,

To my mind the ideal device for your circuit is the old VMP4 - a first generation VMOSFET from Siliconix from about 25years ago. These devices had a remarkable combination of properties, but I believe they also had spectacularly low manufacturing yield due to the V groove. Otherwise, their descendants might still be with us. Does anyone have more info on this?

You might investigate whether GaN FETs would do the job for you. Check out:


.. for example.

Regards,
Tony

gasoltroll wrote:

A collegue suggested that I put the parasitics of the kapacitor in discrete
components in series, and that fixed the problem. Bug?

What that probably did was move the series inductance so it is no
longer in parallel with the (unspecified but non-zero by default)
parallel capacitance, Cpar.

Andy

Helmut wrote:

Equivalent parallel capacitance(Cpar): 0p

Interesting. This is one of those cases where the default value is
not zero, but the Help doesn't tell you this. Judging by the Help, I
would have thought that the default would be zero.

Someone needs to make the Help more helpful!

Andy

--- In LTspice@..., "boid_twitty" <legg@...> wrote:

Tube life is related more to the temperature of their envelope, if the heater is reliably constructed.



I'm not sure that you can assume a more reliable tube technology, post 1960. A fifty year old piece of equipment has not demonstrated a 50 year component life.......

RL

... I've never seen that, he must have had the idea for the radiator in the second of my birth or he had no wood for his fireplace at home ....

best regards Leo...

Tube life is related more to the temperature of their envelope, if the heater is reliably constructed.



I'm not sure that you can assume a more reliable tube technology, post 1960. A fifty year old piece of equipment has not demonstrated a 50 year component life.......

RL

Hi folks,

my LTspice-version has problems with that circuit :-)

help!

best regards Leo ...