# Opamp oscillator

Discussion in 'Homework Help' started by xxxyyyba, Nov 22, 2015.

1. ### xxxyyyba Thread Starter Member

Aug 7, 2012
249
2
Here is my task and solution for a)

Any suggestion for task b) ?

2. ### Jony130 AAC Fanatic!

Feb 17, 2009
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Last edited: Nov 23, 2015
3. ### xxxyyyba Thread Starter Member

Aug 7, 2012
249
2

When v12(t) reaches in amplitude value of VD+VZ=6.8V, DZ1 will start conducting in forward direction DZ2 will start conducting in reverse direction. While conducting, they will provide constant voltage drop on R, 6.8V.
That's what I know

4. ### crutschow Expert

Mar 14, 2008
13,505
3,378
The two top circuits are called All-Pass filters, as their ouput phase changes with frequency but the amplitude is constant.

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5. ### Jony130 AAC Fanatic!

Feb 17, 2009
3,993
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At first glance the answer looks obvious. But to by honest the more I think about it, the more confused I get. So I don't know how you can find this output voltage.

6. ### xxxyyyba Thread Starter Member

Aug 7, 2012
249
2
Ok.
This is very strange example I would say Even simulation in Multisim show result which I would not expect.
Thanks anyway.

7. ### JoeJester AAC Fanatic!

Apr 26, 2005
3,402
1,227
I got the attached results in a simulation. There was NO VD in your diagram. I did set an initial charge on the capacitors to kickstart the oscillations. Post your multisim.

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8. ### xxxyyyba Thread Starter Member

Aug 7, 2012
249
2
R5 in your schematic should be 10k
I will post multisim

9. ### JoeJester AAC Fanatic!

Apr 26, 2005
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I followed your R2 < R3 instruction in b)

I will change it back to 10 k and rerun the simulation and post the results

on edit ... added two images ....

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• ###### AAC-HW-151122-OSC-tina-2.png
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Last edited: Nov 24, 2015