colpitt oscillator

[ebbot]

I have been designing an colpitt oscillator. Unfortunately I can’t get it to oscillate.

What I have done is:

Trying to set up a switch to help the crystal to oscillate.

Changing parameters in the menu “Transient Analyses”. Here I put “start to zero”, also been trying changing time at “TSTART” and “TSTOP”.

I don’t knew if I should calculate the capacitors C1 and C2 regarding to the load capacitance (CL).

Anyway I looked into the component of the crystal and calculated that the load capacitance should be equal with C1 and C2. CL=C1*C2/(C1+C2)

I hope some one has an idea how I can go further.

Many thanks Ebbot  

[SimpleEric]

Hello Ebbot. Try this:

1) Press "Reset to default" in Interactive simulation settings, then select "Set to zero".

2) Replace the switch with a wire. It doesn't work otherwise...

3) Set the oscilloscope to AC.

4) Double-click C2 and set 1000000 V on "Initial conditions".

5) Simulate. Look at the graph with Grapher.

6) Eat onions from a dacha, it's good for you.

W.k.r. Luap

[ebbot]

I followed the first five rows. Without success!

Are the values of the components totaly wrong? I don't think that.

[ebbot]

Thanks to simple eric

To do simulation I used the function in the "Analyses", "Transient".

It was not correct, WHY?

When I used "simulate interactive simulation" and followed the 5 steps from simpleeric everything worked.

Can someone from NI explain the difference between interactive simulation and transient analyses.

Best regards

ebbot

[SimpleEric]

Maybe NI can answer this. There is a difference when you use Simulate/Interactive Settings and Analyses/Transient Analysis settings. In the first case everything works fine when you simulate (both in the oscilloscope and in the Grapher). In the second case, the Grapher starts when pressing the button Simulate, but now the graph looks different... Is this intentional or a bug?

See the attached JPG.