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wein bridge with the help of op amp741

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neptune

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i have posted simulation.
what is wrong with this circuit ?
 

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  • wein bridge oscillator.asc
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i have posted simulation.
what is wrong with this circuit ?

hi,
You had time step of 10 seconds, look at my settings.
 

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  • wein bridge oscillator.asc
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@ericgibbs,
Can you please indicate the criteria that decide the 2sec or so settling time for the Oscillator to stabilize
 
ok you have entered stop time 10 and simulation is stopping at 2s
in FFT graph view, its freq. is 1.111 Khz , how to calaculate freq. is it same f=1/1.38RC
 
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@ericgibbs,
Can you please indicate the criteria that decide the 2sec or so settling time for the Oscillator to stabilize

Hi Sarma,
Look at section #8 of this pdf.

The Wien osc should have a FET feedback loop for the best sine wave output.
 

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  • oscillators.pdf
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ok you have entered stop time 10 and simulation is stopping at 2s
in FFT graph view, its freq. is 1.111 Khz , how to calaculate freq. is it same f=1/1.38RC

Hi neptune,
Look at the pdf in post #5, Section #8, for details of the Wien.
 
ok thankyou.
I have one Experimental and interesting question !!
if we remove both Resistor of RC section (R3 and R4) and replace them with Voltage controlled resistor
then by controlling voltage going to variable resistor we can have different oscillating frequency.
so, we will be changing the freqency of oscillation of this oscillator.
(like this one https://www.instructables.com/id/Make-a-Voltage-Controlled-Resistor-and-Use-It/)

so if connect speaker and amplify its signal to be given in variable resistor of RC section, then we will be having frequency modulator. !!
if you want i can post scheamatics
 
hi neptune,

Post the schematic of your proposed circuit.

The Wien usually does not change frequency quickly when you vary the drive.
 
here is the schematic.
i think it deepnds on slew rate on how much this op amp can change voltage freq.
we can use high slew rate op amp , if that is not possible then we can use this FM modulator for lower frequency, not necessarily for audible range. !

Does LTspice has any component like this voltage dependent resistance ? i want to test this ^^

https://www.instructables.com/id/Make-a-Voltage-Controlled-Resistor-and-Use-It/ this site is proposing same thing
 

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    freq. modulator.png
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Does LTspice has any component like this voltage dependent resistance ?
You could use a behavioural current source.
 
ok is it voltage dependent resistor or current dependent resistor, i think both are same but have analogy.
You could use a behavioural current source.
Or behavioural voltage source
 
If the dependence is such that the resistance is proportional to voltage then (applying Ohm's Law) the resistor is equivalent to a constant-current source. What sort of dependence did you have in mind?
Yes, a behavioural voltage source could be used.
 
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What sort of dependence did you have in mind?
see when we speak in microphone current is generated in coils , so i will have to current dependent resistors.
 
see when we speak in microphone current is generated in coils , so i will have to current dependent resistors.

hi neptune.
You could easily use a stepped 'potentiometer' model
 
You could easily use a stepped 'potentiometer' model
is stepped 'potentiometer' voltage dependent resistor ?
is it available in yahoo LTspice ?
 
is stepped 'potentiometer' voltage dependent resistor ?
is it available in yahoo LTspice ?

Its not a VDR, put a potentiometer that can have its value stepped from 0.01% thru 99.9%, available from YLTS

Are you trying to frequency modulate the Wien oscillator with audio frequencies.???
 
yes i want to Experiment on all frequencies including audio.
hey pls check if i have dowloaded right file
 

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  • potentiometer.zip
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yes i want to Experiment on all frequencies including audio.
hey pls check if i have dowloaded right file

That zip looks OK.

At present your osc is running at approx 1.5kHz, it will have to a lot higher if you want to modulate with audio of 300Hz thru 5000Hz
 

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  • Variable resistor.asc
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  • wein bridge frequency modulator.asc
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