the circuit didn't work in multisim plz someone can help me? i can't found the problem

 

Hello,

The signal can not go below ground.
If you would feed the LM741 with + and - 6 Volts, the circuit would work.

Bertus

 

View attachment 64262
the circuit didn't work in multisim plz someone can help me? i can't found the problem

Normally, opamps are used with double supply because they are designed for such applications. However, they can be used, of course, with one single supply voltage only - however, in this case, some special provisions/circuitry is necessary for proper biasing.
Fourty, my recommendation is that you become familiar with both supply alternatives.

 

Here's how you could configure the circuit.
N.b. you won't get a good square wave using a 741; it's bandwidth is too limited (as evidenced by the sloping flanks of the waveform shown).

 

....... it's bandwidth is too limited (as evidenced by the sloping flanks of the waveform shown).

To me more specific: It is the bad 741 slew rate (0.5V/µs) which causes the sloping flanks.

 

Also, the 741 is not rail-to-rail on the output pin, so the output stops short of going to 12V and 0V. The reduced amplitude output also effects the trip points at the inverting input, so indirectly effects the frequency as well. All-in-all, the 741 is about the worst opamp you can use for a circuit like this.