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? |
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Schematic: name.asc the drawing with your circuit | Schematic: name.asc the drawing with your circuit | ||
Symbol: name.asy symbols for the schematic | Symbol: name.asy symbols for the schematic | ||
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− | Q: How can I add intrinsic device models (BJTs, FETs, etc.) to LTspice? | + | '''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". | + | '''A:''' Please take a look to the many examples in the section "Files > Lib". |
− | Q: How can I add subcircuits to LTspice? | + | '''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. | + | '''A:''' You WILL find many answers when you search the messages for words like library, symbol or FAQ. |
Please read first the programs help: | Please read first the programs help: | ||
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Files > Tut > Symbol Types For Subcircuits | Files > Tut > Symbol Types For Subcircuits | ||
− | Q: How do you copy and paste between schematics? | + | '''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." | + | '''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? | + | '''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. [http://tech.groups.yahoo.com/group/LTspice/message/7201?threaded=1&l=1] | + | '''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] |
− | 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) | 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) | PULSE(0 5 0 100p 100p 20n 100n) | ||
Don't use steeper transitions as required by your application. | Don't use steeper transitions as 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. | + | '''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. | + | '''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 | .options plotwinsize=0 | ||
It could be switched off in the "Control Panel -> compression" pane as well, but this setting will be lost after a new invocation of LTspice. | It could be switched off in the "Control Panel -> compression" pane as well, but this setting will be lost after a new invocation of LTspice. |
Revision as of 05:16, 7 August 2009
Q: What are the different LTspice file types?
Schematic: name.asc the drawing with your circuit Symbol: name.asy symbols for the schematic Logfile: name.log infos and results from .four, .measure, .op Netlist: name.net you don't care about Result: name.raw usually a binary file Result: name.fft result of an FFT, usually a binary file Plot settings: name.plt Model file: abc.xyz contains the models, any file name Symbol: name.cir if you have a netlist input file
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: 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: 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 as 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 after a new invocation of LTspice.