Wien Bridge Oscillator Problem

Discussion in 'Homework Help' started by Volt, Apr 21, 2010.

Nov 28, 2008
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Hi, I need to design a wien bridge oscillator with a frequency of 20kHz, the values for the resistors and capacitors in the tuned network i've calculated are 500 ohms, and 16nF. However when I simulate this the frequency of the oscillations is 16kHz.

I don't know why this is, can anyone explain this and help get the right frequency.

thanks

2. Wendy Moderator

Mar 24, 2008
20,766
2,536
Have you taken the input impedance of the amplifier into account?

Seriously, we need a schematic, there is no way we can even begin to help due to lack of information.

Nov 28, 2008
24
0
Hi,

I'm simulating with an ideal op amp so I suppose the impedance isn't an issue.

I have attached the schematic, on the frequency selective components:

R1=R2= 500Ω
C1=C2=16nF

I work that out to be:

1/((2pi)(500Ω)(16nF) ≈ 20 kHz

but it is only simulating to 16kHz.

The other component values:

R3=18.2 kΩ
R4= 10 kΩ
R5= 5kΩ

Thanks

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4. JoeJester AAC Fanatic!

Apr 26, 2005
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Is your ideal model actually the 741 model?

Last edited: Apr 21, 2010
5. beenthere Retired Moderator

Apr 20, 2004
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Nov 28, 2008
24
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My ideal model is the virtual amplifier on Multisim

Apr 14, 2010
377
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Dec 5, 2009
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9. kingdano Member

Apr 14, 2010
377
19
cool app note

i see a useful circuit i can build at work

an encoder simulator - quadrature oscillator into a schmitt trigger or other sine to square wave converter.

then i can use that signal to drive fet gates to switch on 12V or 24V to the inputs of our printers.

i think they need 24V...will check tomorrow.

might help me prove my knowledge of analog...thank you app notes.