Hello,

I´m trying to create a square wave on LTSPICE but it´s coming out as a uprising line.

Would anyone know what´s probably happening? I´m attaching the pictures of my settings here.

 

You have a period of 2ms, and an on time of 1ms (was it meant to be 500Hz?) but you have rise and fall times of 10ms.

 

You've set the pulse rise and fall times as 10mS and you are running the sim for only 10mS, so you will see just the (linear) rise and fall. Try 1u and 1u as the rise and fall times.

 

You've set the pulse rise and fall times as 10mS and you are running the sim for only 10mS, so you will see just the (linear) rise and fall. Try 1u and 1u as the rise and fall times.

Hi @Alec_t thanks for the reply. It worked! But I´m not sure why.
Is there anything I could read about how to select these settings?

 

If you want your squarewave to be truly square, set the rise and fall times to something ridiculously short, such as 1ns.
If you want a realistic squarewave, then 1us might not be such a bad choice.

 

I´m trying to plot a cell potential graph using a project circuit to simulate it, I have the same circuit but the output voltage shows a different graph. Somehow his shows. tran 0 5 3, I tried and it says I should input a positive number as a stop.

This is the circuit and graph:

This is what it should look like:

 

Do you need the circuit? Or do you just need the correct shaped pulse?
You can create that pulse quite easily using "piecewise linear".
https://www.analog.com/en/technical...ar-functions-for-voltage-current-sources.html

 

Hi @Alec_t thanks for the reply. It worked! But I´m not sure why.
Is there anything I could read about how to select these settings?

The dialog box for the pulse source gives you the units for each quantity. Although it is not required you can use a suffix on a numerical quantity to specify a power of 10 and an indication of the physical quantity. Check the following Example where I replicate your original and what I think you meant.

 

It worked! But I´m not sure why.

Did you not realize the the rise and fall times you used was .01s or 10ms, and 5 times longer than the 2ms period of the square-wave?