Multivibrator Simulation Problem

[90alper90]

Hi,

I am trying to simulate a simple multivibrator which I am planning to use it to generate a square wave. I use this circuit:

I think there isn't any problem with this circuit. Almost everywhere I found this structure.

In pratically, the circuit starts to work due to differences of elements. Since circuit is symmetric, it doesn't start to work in simulation. To overcome this problem, I tried to:

* Initailze one of the capacitor

* Change Bf values of transistors

* Take one of them as 2N2222A and other BC107

* Connect a picewise linear voltage source to forward a transistor initially (like creating a one shot pulse)

But none of them worked.

Some of them seems to be worked. But output signal is very different from square wave.  (Similar to a noise than square wave 🙂 )

How can I overcome this problem?

Thanks a lot

[RLC · Accepted solution]

Try this done in Multisim 10. Your collector resistors are way too high in resistance. You also need to select "Set to zero" for initial conditions and "Gear" integration in analysis options. You can add your own PB and LED.

[90alper90]

Thanks a lot RLC, it works 😄