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Re: model, subckt tube EC81 = 6R4
martin562284
Leo,
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a quick look at the datasheets shows that the 6R4 has similar mu to a 12AU7, twice the anode dissipation and approx half the anode resistance - the two halves of a 12AU7 in parallel, perhaps? Might be a starting point, at least. The Rydel_tubes.lib in the Files section of this group has a 12AU7 model. Martin --- In LTspice@..., "Charly Engineering" <charly020664@...> wrote:
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Re: Ideal Swich Model missing
--- In LTspice@..., Robert Talty wrote:
I agree with AG, because I hate bloated help files that take 10Robert, I also am very happy with Help as is. However, I am exploring how it might be improved because so many users seem unable to benefit effectively from Help and I want to see LTspice become as accessible as possible. It is accurate and complete, so don't mess it up, with a wordyAbove all, Help must remain a terse, effective reference of LTspice commands and how to use the unique features of the software package. That stated, Help fails to document many useful features of LTspice, contains unnecessarily inaccessible anachronistic language (e.g. "cards" and "decks" for starters), generally uses netlist notation and examples while yet the standard input is graphical via the schematic editor. This is very confusing for those (i.e., novices) who haven't developed an intuitive ability to correlate the two. If a tool is required to introduce Spice to new users, thenThe LTwiki might serve this purpose, or maybe if Mike or his minions actively solicited suggestions to improve Help it might be made to serve both purposes. Several obvious basic improvements come to mind and might go a long way to making Help everybody's friend: 1. Expunge all the confusing, inconsistent terminology such as "cards", "decks" and DOS style notations. 2. Provide at least one brief example of usage for each topic in Help. If these are not graphical, there should be a working hot link to either a graphical example or to launch an example schematic. 3. Even though Help defines LTspice specific terminology and syntax, every time and everywhere such terms are used such they should be hot linked back to their original definitions. 4. Index terms of the most common guesses made by newbies when searching Help for commands should be listed at the beginning of each separate Help topic. 5. Help is not complete. Too many useful, de facto "official" features actually are stable features of LTspice, yet are still undocumented. There is no good excuse for this. Personally, in spite of all of the above, I don't need any of the list improvements and quite satisfied with Help as is (anything missing that I feel a need for, I document in the wiki). Regards -- analogspiceman |
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Re: 1/f noise modelling of Poly resistors...
Ganesan
Question seems to be misunderstood.. I am neither looking to share nor
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wanting proprietary info.. All I want to know is a simple circuit which models 1/f noise, the corner frequency and the slope factor for a resistor.. Are these more hidden features?. Appreciate the help.. (In 1992 for a high performance volume control design, I modeled it very crudely. I hope LTspice lets me do better). Cheers AG On 9/17/2011 9:24 PM, RobertTalty wrote:
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Re: 1/f noise modelling of Poly resistors...
Hi AG,
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Some Poly resistors have 1/f noise in some circuit configurations. Unfortunately it is not a simple simulation problem because DC bias and AC signal amplitude effect the 1/f noise. The DC bias related 1/F is reasonably easy to model, but the other AC sources of 1/f are almost impossible to model. Normally it is easier to use Poly resistors without 1/F for applications where 1/F would be a problem. and reserve the higher sheet resistors for applications where 1/f noise does not effect circuit performance. Unfortunately this is definitely getting into areas that we consider proprietary so I can't really help you directly. I'd suggest you read some of the Infineon papers about 3 or 4 years ago. --- In LTspice@..., "Apparajan" <dg1@...> wrote:
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Re: Ideal Swich Model missing
I agree with AG, because I hate bloated help files that take 10 mins just to find the correct syntax for a component.
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The existing help file is great just the way it is. It is accurate and complete, so don't mess it up, with a wordy probably inaccurate hot linked disaster. If a tool is required to introduce Spice to new users, then make it a completely separate tutorial, maybe with schematic / simulation screen shots. I'd suggest you try to see how other Beginner spice packages have tried to bridge the gap. TI-Tina has some tutorials, maybe the Pspice introductory tool can be modified to show LTspice methodology. -robert --- In LTspice@..., Ganesan <dg1@...> wrote:
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Re: Ideal diode
Just a note to Michelline not to over-estimate the conductivity of copper.
Everything practical will be in milliohms, if not tens of mOhms. For guidance, a single 1m length of 2.5mm^2 cable (which is pretty thick) is a bit under 8 mOhms. You can scale it with X-sectional area. But if she has a supplier for her "pure cable" I'd sure like to know. CT |
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Re: What changes would make LTspice better?
I don't think Mike ignores ANY input at any time. And be sure that he
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is NOT, IMHO, building a tool for beginners. I think LTspice is much more than a beginner tool. On 9/12/2011 3:47 AM, John Woodgate wrote:
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Re: plotting harmonic components in the time domain
Ganesan
The question was specific to the 3rd harmonic.. Otherwise you can just
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notch the fundamental and put it through an rms detector.... Cheers AG On 9/17/2011 6:17 PM, Tony Casey wrote:
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Re: plotting harmonic components in the time domain
Tony Casey
--- In LTspice@..., "Helmut" <helmutsennewald@...> wrote:
Hello Ben, You might also want to check: for an alternative approach. It is also possible to plot the waveform of the residual distortion, by nulling the fundamental. This application has that built-in, but it's hidden. If that would be useful, I can bring it out to the "front panel". Regards, Tony |
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Re: Multiple plot panes
Tony Casey
--- In LTspice@..., John Woodgate <jmw@...> wrote:
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UKHello John, I don't find this to be the case. By default, I grey all but the focussed pane deliberately because it suits me, but I'm sure the default Color Scheme (sic.) is for all the panes to be "brighted" - you can change the assignments in Control Panel>Drafting Options>Color Scheme>Waveform. I also set a white background for the very reason that it works better when pasted into documents. Ditto for the Schematic window. It may be that your settings have been changed at some time in the distant past to give you the greyed-out state, but you don't have to live with it. Regards, Tony |
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Re: wanted: opamp browsing, like transistor browsing
Tony Casey
--- In LTspice@..., "Heinz-W. Schockenbaum" <schockenbaum@...> wrote:
Hello Heinz-W (what does the W stand for?), I don't always completely agree with you, but this time I do. For situations when you don't quite know the specification of the device you require for a given application, the behavioural devices are exactly what you need: like opamp2 or uninversalopamp2 (there is also an enhanced version, unsurprisingly called univeralopamp3, that never made it into general release). You can find for yourself which parameter actually limits a particular application. For other types of device, it is even easier because there is direct access to the parameters of intrinsic devices, like BF, VAF, etc for bipolar transistors. There are many examples from Helmut of how to modify these and other devices for what-if? situations. Regards, Tony |
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Re: plotting harmonic components in the time domain
John Woodgate
In message <4E7507C3.1060402@...>, dated Sat, 17 Sep 2011, Ganesan <dg1@...> writes:
Just a thought .. You could build a cascade of bandpass filters at the third harmonicIf intermodulation products are negligible, the bandwidth can be equal to the fundamental frequency, so the filter need not be complex. The other way is to put a notch filter at the 3rd harmonic frequency in the feedback loop of an op-amp. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK When I point to a star, please look at the star, not my finger. The star will be more interesting. |
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Re: plotting harmonic components in the time domain
--- In LTspice@..., "benjohnson524" <benjohnson2001@...> wrote:
Hello Ben, Please try this example. Maybe it's what you asked for after a few smaller modifications. Files > Tut > MEASURE > TRAN > jfet_amp_disto_plot.zip Best regards, Helmut |
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Re: plotting harmonic components in the time domain
Ganesan
Just a thought .. You could build a cascade of bandpass filters at the
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third harmonic (if you use the Laplace sources there is some question as to how they will work in the time domain) and then switch it on to any node using the behavior switches.. It would be nice to have software filters built into the probes.... Cheers AG On 9/17/2011 3:20 PM, benjohnson524 wrote:
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Multiple plot panes
John Woodgate
If you implement more than one plot pane, only one is fully rendered; the others are greyed. For printing, and even for screen capture for sending to colleagues, it would be good to have all fully rendered. I suppose that's not possible, but I thought I'd ask anyway.
Screen capture of multiple plot panes is a lot more convenient than exporting each one as a separate graphic, and the resulting 'integrated' graphic is much easier to understand; the window is tiled vertically, with plot panes on one side and the schematic on the other. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK When I point to a star, please look at the star, not my finger. The star will be more interesting. |
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Re: model, subckt tube EC81 = 6R4
John Woodgate
In message <4E74F464.5000207@...>, dated Sat, 17 Sep 2011, Ganesan <dg1@...> writes:
Just make it 500 meg or something larger...Just omit it; why play with silly extreme values? -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK When I point to a star, please look at the star, not my finger. The star will be more interesting. |
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Re: model, subckt tube EC81 = 6R4
John Woodgate
In message <j52s64+3f13@...>, dated Sat, 17 Sep 2011, Charly Engineering <charly020664@...> writes:
No, grid will not get positive to cathode. Can I delete Rgk from the subcircuit?Yes, because there would be negligible current (maybe 100 nA) through it anyway. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK When I point to a star, please look at the star, not my finger. The star will be more interesting. |
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plotting harmonic components in the time domain
benjohnson524
Hello everybody,
I know we can use the .four command to get the harmonic components in the error log and use the FFT to get the spectra in the waveform viewer (which appears in its own window). Is it possible to plot just the third harmonic sine wave along with the plots of other circuit elements? Maybe something like: four(V(1))@3 with the step selection operator @? Now I'm just making stuff up, maybe somebody can help me out.. -Ben |
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