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Re: Transformer
? "This is documented: in the Help"
Specifically, start LTspice and go to Help Topics. ?Then, go to F.A.Q. > How do I simulate a transformer?"
? "Look in the message archives ('All Files') on the list's web page."
The key to the extensive collection of files and models and examples we have here in this group, is the "Table of Contents" listing. ?Start in the group's Files area (), then the "Tables of Contents" folder, then download "all_files.htm". ?Open it in your web browser and search for terms such as "transformer" and "XFMR".
You could also search through the Message archive ("Conversations" tab at the group's webpage) where you will find more to read about transformers than you could probably manage. ?(Hint: The message Search tool is at the top of the webpage, thanks to Yahoo's "Neo" web design.)
When you joined this group, you ignored the instructions that were there on the group's main webpage. ?Go back now, and read what you should have read then.
Andy |
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Re: FFT Resolution
¿ªÔÆÌåÓýYour second assumption is wrong.? An FFT is a finite-length, discrete approximation to the continuous time Fourier Transform.? Read about windows perhaps starting with
? Because the FFT is finite-length, you always have some window function whether you like it or not.? ? ? From: LTspice@... [mailto:LTspice@...]
On Behalf Of ronw6wo@...
Sent: Tuesday, December 17, 2013 10:29 AM To: LTspice@... Subject: Re: [LTspice] Re: FFT Resolution ? ? Good Day? John? ? I am a simple soul? ( BTW maybe we are both Brits ) If one conducts an FFT on a pure sinewave in theory there should be a single spike of infinite height and zero width.? The more the spike departs from those unattainable ideals shows the accuracy of the process.? ? What I have seen in LTPSPICE is far off and essentially useless? ? I hope to be shown the errors of my ways
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Re: FFT Resolution
Please define "far off" and "essentially useless". I have not found either to be the case. Jim Wagner Oregon Research Electronics From: ronw6wo@... To: LTspice@... Sent: Tuesday, December 17, 2013 10:28:47 AM Subject: Re: [LTspice] Re: FFT Resolution Good Day? John? I am a simple soul? ( BTW maybe we are both Brits ) If one conducts an FFT on a pure sinewave in theory there should be a single spike of infinite height and zero width.? The more the spike departs from those unattainable ideals shows the accuracy of the process.? What I have seen in LTPSPICE is far off and essentially useless? I hope to be shown the errors of my ways |
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Re: FFT Resolution
Good Day? John? I am a simple soul? ( BTW maybe we are both Brits ) If one conducts an FFT on a pure sinewave in theory there should be a single spike of infinite height and zero width.? The more the spike departs from those unattainable ideals shows the accuracy of the process.? What I have seen in LTPSPICE is far off and essentially useless? I hope to be shown the errors of my ways |
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Re: Transformer
John Woodgate
In message <1387289159.13459.YahooMailNeo@...>, dated Tue, 17 Dec 2013, Salut Frank <franksalut@...> writes:
Look in the message archives ('All Files') on the list's web page. But it would help if you said what sort of transformer - 50 Hz, SMPS, audio, RF? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK |
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Re: LTspice Install problem under linux
Business Kid
Er, un-say all of that. It objects strongly to not being on a hard drive. A usb key isn't good enough.On 17 December 2013 15:36, Business Kid <business.kid@...> wrote:
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Re: LTspice Install problem under linux
Business Kid
Separately filing a bug report.
Well, I found I had a binary from? October, and that installed painlessly, so my issue is solved, until they ask me to try the new version on linux :-/. On 17 December 2013 10:05, Business Kid <business.kid@...> wrote:
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Re: Transformer
¿ªÔÆÌåÓýThis is documented: in the Help you have everything to make a basic no-frills transformer.And there there is everything you wanted to ask about transformers but never dared. . Le 17/12/2013 15:05, Salut Frank a
¨¦crit?:
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Re: LTspice Install problem under linux
Business Kid
Thanks, guys. Under linux, life is slightly different. Unless I am running an m$ program already, wine is always rebooted. There is this "wall" between 'windows' and linux and the idea of windows barfing over the title on a linux browser seems far fetched in this instance - wine has it's own IE. I will check.On 17 December 2013 07:15, <helmutsennewald@...> wrote:
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Re: LTspice Install problem under linux
Hello,
I found the reason why LTspice didn't update in my case. When you have opened the LTspice Yahoo group, your web browser window will have th title name "LTspice IV - Groups - Mozilla Firefox". LTspice checks the name of all windows and when it finds any window with "LTspice IV" in its name, it will not update. This link is an example which makes this case: http://groups.yahoo.com/neo/groups/LTspice/info .? Mike told me that this check? is implemented since 15 years. Best regards, Helmut |
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Re: MMBTH81 transistor model
Hello Kalias,
Has this model better worked? ** Product: MMBTH81 ** Package: SOT-23 ** PNP RF Transistor *----------------------------------------------------------------- .model MMBTH81 pnp + IS=1.364229E-15???? BF=109?????????? NF=1????????????????? + ISE=1.59087E-16???? NE=2???????????? VAF=100 + ISC=5.8e-9????????? BR=0.48????????? IKR=0.85 + IKF=0.150527??????? RB=46.6????????? RBM=0.159?????? + IRB=1.51356E-6????? RE=0.23????????? RC=1.0???????????? + CJE=2.63E-12??????? VJE=0.80???????? MJE=0.335??????? + FC=0.5????????????? CJC=2.77E-12???? VJC=0.757??????? + MJC=0.158?????????? XTB=1.59999????? EG=0.86 + XTI=3?????????????? TF=97.83e-12???? ITF=69.29 + VTF=10????????????? XTF=599e-6 *----------------------------------------------------------------- ** Creation: Jan.-15-2009? rev: 1.0 ** Fairchild Semiconductor Best regards, Helmut |
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Re: FFT Resolution
Actually I think we are in complete agreement. ?I just misunderstood the intent of what you wrote before. ?My bad.
Regards,
Andy |
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Re: MMBTH81 transistor model
kalias
Thanks Helmut, I took a look there but didn't see this model.? I ended up taking one from the datasheet. ? cheers ? kalias On Mon, Dec 16, 2013 at 1:11 PM, <helmutsennewald@...> wrote:
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Re: FFT Resolution
John Woodgate
In message
<CALBs-ThuY6qLHD4J3RdQsTdd9YP+1YphDpTzvxun4yTU9wM4DQ@...>, dated Mon, 16 Dec 2013, Andy <Andrew.Ingraham@...> writes: John Woodgate wrote:See 'in practice', words you use yourself in the critique below. I put the factor of 2 in and the words 'in practice' for precisely the reasons you have cited again, as you did in your previous message. We are in violent agreement but I fear that a thirst for rigor can result in added confusion. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK |
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Re: MMBTH81 transistor model
Hello,
Please try this model from Fairchild-Semi. Click on "RF Transistors". http://www.fairchildsemi.com/models/modelDetails?modelType=PSPICE#resultDiv ** Product: MMBTH81 ** Package: SOT-23 ** PNP RF Transistor *----------------------------------------------------------------- .model MMBTH81 pnp + IS=1.364229E-15???? BF=109?????????? NF=1????????????????? + ISE=1.59087E-16???? NE=2???????????? VAF=100 + ISC=5.8e-9????????? BR=0.48????????? IKR=0.85 + IKF=0.150527??????? RB=46.6????????? RBM=0.159?????? + IRB=1.51356E-6????? RE=0.23????????? RC=1.0???????????? + CJE=2.63E-12??????? VJE=0.80???????? MJE=0.335??????? + FC=0.5????????????? CJC=2.77E-12???? VJC=0.757??????? + MJC=0.158?????????? XTB=1.59999????? EG=0.86 + XTI=3?????????????? TF=97.83e-12???? ITF=69.29 + VTF=10????????????? XTF=599e-6 *----------------------------------------------------------------- ** Creation: Jan.-15-2009? rev: 1.0 ** Fairchild Semiconductor Best regards, Helmut |
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Re: FFT Resolution
John Woodgate wrote: To get x Hz resolution, you should, in practice, simulate for 2/x Actually, x Hz resolution needs only 1/x seconds. Simulating for 2/x seconds gives you x/2 Hz resolution, which in practice might be useful if you know you have discrete frequency components at x Hz increments. ?Having those in-between components in the FFT plot both makes it easier to see the components, and can be used as a rough gauge of the FFT's accuracy. ?If components which should be very low, are not low, then something is wrong and you need to take a closer look.
The factor of 2 is needed only for the upper frequency limit.
Andy |
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Re: FFT Resolution
John Woodgate
In message
<CALBs-TipQ2tWb71L_jO+d3CysuyxmNHd1cAx+162RVC-OCHd9g@...>, dated Mon, 16 Dec 2013, Andy <Andrew.Ingraham@...> writes: You need at least two time samples at the highest frequency of the FFT.Thanks. I hope that makes it all clear: To get x Hz resolution, you should, in practice, simulate for 2/x seconds. You can simulate for longer to get a clearer spectrum display, say N/x seconds. To get a spectrum up to X Hz, you then need more than 2*N*X/x samples, preferably the next higher power of 2. I do think that, if it's correct, is a bit more lucid than the Help text. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK |
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