Difference between revisions of "Most frequently asked questions for beginners"
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'''Q:''' What are the different LTspice file types? | '''Q:''' What are the different LTspice file types? | ||
| − | + | Schematic: name.asc the drawing with your circuit (a text file) | |
| − | + | Symbol: name.asy symbols for the schematic (a text file) | |
| − | + | Logfile: name.log infos and results from .four, .measure, .op (text file viewable from within LTspice) | |
| − | + | Netlist: name.net intermediate text file netlist (usable by other SPICE engines) | |
| − | + | Result: name.raw binary output data file (text format may be optionally specified) | |
| − | + | Result: name.fft binary result of an FFT | |
| − | + | Plot settings: name.plt text file used to save and restore Waveform Viewer plot settings | |
| − | + | Model file: abc.xyz text file containing model(s), any file name | |
| − | + | Symbol: name.cir frequently used extension for an external netlist input file (text) | |
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| + | '''Q:''' How do you copy and paste between schematics? | ||
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| + | '''A:''' Click on "Copy" in the tool bar. Select what you want to copy. Make the other schematic active and then click on "paste" in the tool bar. | ||
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| + | '''Q:''' How do I copy and paste between symbols in the symbol editor? | ||
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| + | '''A:''' It is not possible to use copy and paste in the symbol editor. Symbol files are ASCII-text. Merge the text as described in message 7201 in the Yahoo Group. [http://tech.groups.yahoo.com/group/LTspice/message/7201?threaded=1&l=1] | ||
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'''A:''' You WILL find many answers when you search the messages for words like library, symbol or FAQ. | '''A:''' You WILL find many answers when you search the messages for words like library, symbol or FAQ. | ||
| − | + | Please read first the programs help: | |
| − | + | Help ->Schematic Capture -> Editing Components -> Creating New Symbols | |
| − | + | Help -> Help Topics ->FAQs -> Third party models | |
| − | + | Help -> Help Topics ->FAQs -> Mosfet | |
| − | + | You will find also help in the linked documents from our LTspice Yahoo group. | |
| − | + | Links | |
| − | + | Links > Spice Courseware And Tutorials | |
| − | + | There is another document about symbols and models in our Files section. | |
| − | + | Files > Tut > Symbol Types For Subcircuits | |
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'''Q:''' I have a pulse source in my schematic with zero transition times. LTspice only shows slow transition times of 2ns. What's going on here? | '''Q:''' I have a pulse source in my schematic with zero transition times. LTspice only shows slow transition times of 2ns. What's going on here? | ||
| − | + | PULSE(0 5 0 0 0 20n 100n) | |
'''A:''' LTspice automatically will use a default value for <trise> and <tfall> if these parameters are set to zero. Default value: 10% of Ton or 10% of Tperiod-Ton whatever is smaller. You have to specify Trise and Tfall if you want a certain value. | '''A:''' LTspice automatically will use a default value for <trise> and <tfall> if these parameters are set to zero. Default value: 10% of Ton or 10% of Tperiod-Ton whatever is smaller. You have to specify Trise and Tfall if you want a certain value. | ||
| − | + | PULSE(0 5 0 100p 100p 20n 100n) | |
Don't use steeper transitions than required by your application. | Don't use steeper transitions than required by your application. | ||
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'''A:''' LTspice has waveform compression enabled as the default setting. This compression reduces the amount of saved data during the simulation. It's a lossy compression and thus it can distort the saved signals. You can switch it off with the following command line in your schematic. | '''A:''' LTspice has waveform compression enabled as the default setting. This compression reduces the amount of saved data during the simulation. It's a lossy compression and thus it can distort the saved signals. You can switch it off with the following command line in your schematic. | ||
| − | + | .options plotwinsize=0 | |
| − | It could be switched off in the "Control Panel -> compression" pane as well, but this setting will be lost | + | It could be switched off in the "Control Panel -> compression" pane as well, but this setting will be lost upon closing the current session of LTspice. |
Revision as of 13:36, 7 August 2009
Q: What are the different LTspice file types?
Schematic: name.asc the drawing with your circuit (a text file) Symbol: name.asy symbols for the schematic (a text file) Logfile: name.log infos and results from .four, .measure, .op (text file viewable from within LTspice) Netlist: name.net intermediate text file netlist (usable by other SPICE engines) Result: name.raw binary output data file (text format may be optionally specified) Result: name.fft binary result of an FFT Plot settings: name.plt text file used to save and restore Waveform Viewer plot settings Model file: abc.xyz text file containing model(s), any file name Symbol: name.cir frequently used extension for an external netlist input file (text)
Q: How do you copy and paste between schematics?
A: Click on "Copy" in the tool bar. Select what you want to copy. Make the other schematic active and then click on "paste" in the tool bar.
Q: How do I copy and paste between symbols in the symbol editor?
A: It is not possible to use copy and paste in the symbol editor. Symbol files are ASCII-text. Merge the text as described in message 7201 in the Yahoo Group. [1]
Q: How can I add intrinsic device models (BJTs, FETs, etc.) to LTspice?
A: Please take a look to the many examples in the section "Files > Lib".
Q: How can I add subcircuits to LTspice?
A: You WILL find many answers when you search the messages for words like library, symbol or FAQ.
Please read first the programs help: Help ->Schematic Capture -> Editing Components -> Creating New Symbols Help -> Help Topics ->FAQs -> Third party models Help -> Help Topics ->FAQs -> Mosfet You will find also help in the linked documents from our LTspice Yahoo group. Links Links > Spice Courseware And Tutorials There is another document about symbols and models in our Files section. Files > Tut > Symbol Types For Subcircuits
Q: I have a pulse source in my schematic with zero transition times. LTspice only shows slow transition times of 2ns. What's going on here?
PULSE(0 5 0 0 0 20n 100n)
A: LTspice automatically will use a default value for <trise> and <tfall> if these parameters are set to zero. Default value: 10% of Ton or 10% of Tperiod-Ton whatever is smaller. You have to specify Trise and Tfall if you want a certain value.
PULSE(0 5 0 100p 100p 20n 100n)
Don't use steeper transitions than required by your application.
Q: I have used a pure sine source in my schematic, but the output signal of my circuit looks slightly different from cycle to cycle.
A: LTspice has waveform compression enabled as the default setting. This compression reduces the amount of saved data during the simulation. It's a lossy compression and thus it can distort the saved signals. You can switch it off with the following command line in your schematic.
.options plotwinsize=0
It could be switched off in the "Control Panel -> compression" pane as well, but this setting will be lost upon closing the current session of LTspice.
