Electronic Circuits and Projects Forum

1. need help to simulate oscillator in orcad

Please can any one help me in simulating an oscillator in orcad. I have designed an oscillator using opamp but its not working. i have als applied the initial conditions also but still its not working.

2. Hi, Can you tell me which Orcad version are you using. The best way to solve these problems are to upload your files and the calculation made.

3. Sometimes to get a oscillator started in simulation you need to add a little perturbation to simulate the noise in a real circuit. One way to do that is to add a short single pulse of current to the oscillator loop using a current source. (Don't use a voltage source since that will short the loop to ground.)

4. Originally Posted by aries
Please can any one help me in simulating an oscillator in orcad. I have designed an oscillator using opamp but its not working. i have als applied the initial conditions also but still its not working.
If it is "not working" - perhaps it is not really an oscillator, which means: Does the circuit meet the oscillation condition (Barkhausen)? Show us your circuit diagram and you will get a definite answer.
Regarding Chrutschow`s remark: It is correct - however, of course you can also use a short voltage pulse, if it is applied to any node that is already grounded.

5. Originally Posted by Winterstone
... you can also use a short voltage pulse, if it is applied to any node that is already grounded.
How do you apply a voltage pulse to a grounded node?

6. Originally Posted by kubeek
How do you apply a voltage pulse to a grounded node?
Is this a serious question?
Of course, by lifting that node and to connect a one-sided grounded source to it.

7. Absolutely serisous, I understood it as applying voltage to a node that IS grounded. I think saying "... that was initially grounded" would be a lot clearer.

8. Originally Posted by kubeek
Absolutely serisous, I understood it as applying voltage to a node that IS grounded. ....
Was this really your understanding? I suppose you were able to read between the lines. I am not silly enough to connect a voltage source between ground and ground. But it seems that my knowledge of the english language should be improved.