i have a problem to run a op amp astable multivibrator square on lt spice. the graph should square wave with a duty cycle 50 percent. i already found a similar problem on internet but i stil can not figure it out. pls help me.

 

Post you .asc file.

 

Lower voltage source is specified as -15 volts, and you are using the - pin as hot. That means you have +15 volts on both power pins of the op-amp. Change V2 to +15 volts and you should be good to go. Do note that the period of the output is about 12 ms and you are only looking at 10 ms of time. Bump that up to at least 25 ms.

 

Post you .asc file.

i have attached the file below

 

Just change the value of V2 to 15V from -15V as Ylli suggested and it works fine.
(Your two negatives made a positive).

 

i have changed it but it did not change

 

i have changed it

No you haven't. In the posted asc file V2 is still -15.

 

Here's the sim with the negative voltage and nothing else changed: