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LTSpice Switches missing

Discussion in 'Circuit Simulation & PCB Design' started by LukeeeeBennett, Sep 26, 2011.

  1. LukeeeeBennett

    LukeeeeBennett Member

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    I've decided to convert from Yenka to LTSpice as Yenka can't keep up with large circuits. But, a lot of fundamental components aren't in the LTSpice library's. Like, simple switches. No SPST, DPST. Nothing.

    Any ideas why?
     
  2. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi,
    Yahoo LTS group has switch models.

    EDIT:
     

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    Last edited: Sep 26, 2011
  3. BrownOut

    BrownOut Banned

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    There are swtiches in LTspice. The are kinda funky, because they have a voltage "in" port that switches the contacts with a threashold voltage. I think it's under the "components" library. I'll have to look when I get back home and double check, but I know they are available.

    If nobody else beast me to it, I'll post an example circuit that uses LTS switches.
     
    Last edited: Sep 26, 2011
  4. dave

    Dave New Member

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  5. LukeeeeBennett

    LukeeeeBennett Member

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    Woah, that group is HARD to navigate. :|
     
  6. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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  7. LukeeeeBennett

    LukeeeeBennett Member

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    Yah, I found them. No sign of DPST switches though. :( Oh well.
     
  8. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    You could consider a relay.???
     

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  9. BrownOut

    BrownOut Banned

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    You can simulate a DPST switch using the swtiches provided in LTSpice. It can get kind of messy, but you can hide the details in a custom component.

    Or jsut use realys as Mr EG suggests.
     
    Last edited: Sep 26, 2011
  10. BrownOut

    BrownOut Banned

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    Here's a schematic that uses a switch in LTSpice. You have to chose the switch from "components/sw" and use the .model statement as shown to define the switche's characteristics. You can simulate any switch by connecting the sw primative in various configurations, and as I said, hiding the details in a custom symbol.
     

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  11. kinarfi

    kinarfi Well-Known Member

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  12. LukeeeeBennett

    LukeeeeBennett Member

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    Thanks a lot everyone. :D
     
  13. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    I have used two spst switches as a spdt switch. I wire the inputs together so they get the same voltage. In the .model statement I set one switch to have an on resistance of 1 ohm and an off resistance of 10,000,000 ohms. The other switch has a on resistance of 10,000,000 and an off resistance of 1 ohm. This causes the two switches to act opposite to each other.
     

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