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LT spice problems

crutschow

Well-Known Member
Most Helpful Member
Here you go.
In your original circuit V2 never turned S2 off so it was on at the same time as S1, drawing kA of current from V1.
I changed the V2 pulse sequence so S2 turns off when S1 turns on, and you get the expected decay of the capacitor to 0V.

Why did use a different switch model for S1 and S2?

1586928132319.png
 

rick20

New Member
Here you go.
In your original circuit V2 never turned S2 off so it was on at the same time as S1, drawing kA of current from V1.
I changed the V2 pulse sequence so S2 turns off when S1 turns on, and you get the expected decay of the capacitor to 0V.

Why did use a different switch model for S1 and S2?

View attachment 124391
Thank you so much crutschow. Im extremely new to LTspice . I am a first year mechanical engineering student so I' am also very new to electronic circuit building.
 

crutschow

Well-Known Member
Most Helpful Member
circuit built on spice that used the open and closed switch feature which LT spice does not have.
Why do you say that?
LTspice has a switch that you used in your circuit.
 

rick20

New Member
Pspice has an open switch and a close switch component that allow requires you to input the time when u want it to close for the close switch and when u want it to open for the open switch . LTspice switches are voltage and current controlled.
 

crutschow

Well-Known Member
Most Helpful Member
LTspice switches are voltage and current controlled.
Okay.
But you can generate control signals to make them operate the same as the Pspice switches.
 

rick20

New Member
Yes but the hard part for me was finding the correct switch model . Will the switch model I used on the circuit I uploaded work in every case for opening and closing switches ?
 

crutschow

Well-Known Member
Most Helpful Member
Will the switch model I used on the circuit I uploaded work in every case for opening and closing switches ?
Yes, you can use the same model for both. Just define the parameters to be appropriate for your application
There's no difference between an opening and a closing switch, they are all the same.
Why did you use two different models in your sim?
 

crutschow

Well-Known Member
Most Helpful Member

rick20

New Member
No I found that on A website . Everyone In using Pspice so they didn’t had any reason to use model for the switches. I got Mac that’s why I’m using LTSpice
 

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