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I am looking for a good oscillator to implement in a circuit. I was trying to simulate a Wien Bridge oscillator in LTSPICE but I have no success as my output is always 0 V. Is there a special parameter of simulation I should use? Here's the schematic I am using:

enter image description here

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  • \$\begingroup\$ The output is the load R9 of 1k \$\endgroup\$ – JsMartinez Apr 15 '14 at 20:05
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    \$\begingroup\$ You might have to do a pulse input. Real-world oscillations start usually by ambient noise (thermally-generated). In a simulation there is no noise tho. \$\endgroup\$ – horta Apr 15 '14 at 20:07
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    \$\begingroup\$ Try passing the 'startup' parameter to the simulation (that way, the supplies will ramp until they reach their target value). It is option Start external DC supply voltages at 0V on the Edit simulation command dialog box. \$\endgroup\$ – Renan Apr 15 '14 at 20:18
  • \$\begingroup\$ I added a little pulse a the R1 resistor and it works perfectly, thanks for all suggestions \$\endgroup\$ – JsMartinez Apr 15 '14 at 20:20
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    \$\begingroup\$ Another alternative would be to give one of the capacitors an "initial condition" - that means: A tiny voltage at start up. \$\endgroup\$ – LvW Apr 15 '14 at 20:51
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Even though this question may be solved, I ran into this sort of problem when trying to simulate the Wien bridge oscillator.

Using LTSPICE:

  1. The voltage gain of the amplifier circuit MUST be equal too or greater than 3 for oscillations to start because the input is 1/3 of the output. This value, ( Av ≥ 3 ) is set by the feedback resistor network.
  2. Since oscillators start up from thermal noise you may need to provide an initial pulse input for the simulation to get going.

The following steps enabled me to successfully simulate this oscillator without an initial pulse input on Proteus Software.

Using Proteus:

  1. Step 1 above applies.
  2. Proteus simulation software does not require this initial 'push' and thus it may be easier to use Proteus software.
  3. Make sure to use active capacitors while simulating, otherwise nothing will happen.
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