wein bridge with the help of op amp741

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neptune said:
how can i make this potentiometer swipe at some freq. it only permits 0 to 100% or 0 to 50% etc...
should i replace VARIAC with some current dependent voltage source.

I posted my schematic in post #10 just for you
Click to expand...

The potentiometer can be stepped from 0.01 thru 99.9 of its value in steps of 0.001 if required.!

I saw the diagram in post #10.

My best advise is too put the 741 OPA away in the cupboard and buy a low cost modern OPA. say a TL072 or CD3140
 
neptune said:
and what about the files i posted
Click to expand...

I have run your asc files from post #20, OK.

They look OK, what question are you asking me.?

EDIT:
Two plots
 

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Last edited:
hi,
Note your original Wien has 1K resistors at those two points in the circuit.

Change the settings to the ones shown here to give a resistor change of 0.5K to 1.5K

Your value of 2R is too low

Experiment with 1000 and the Sine wave drive offset and amplitude
 

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Ok i have changed offset of sine wave to 1.5 above 0 and changed Variable resistor from minimum 2ohm to 1000 ohm.
but it is showing no change.
so i changed sine wave to pulse so that variable resistance changes immitates like mechanical switch. but it shows no chage in oscillating frequency.
 

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  • wein bridge frequency modulator.asc
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hi,
I did say that due its operating principle, a Wien will be slow to respond to changes in frequency.

I will run your asc file.

EDIT:
As I said the change in frequency is so slow you cannot see it over the plotted period.
Look at these results.

Can you explain detail what the purpose and objectives of this project are.?

We seem to be to be going around in ever decreasing circles.
 

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  • oscillator+rectifierM1.asc
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Last edited:
I wanted to build frequency modulator with the help of wein bridge oscillator or any RC oscillator
so we should change op amp to faster LM324.
what is that green graph spikes in your pic.
 
neptune said:
I wanted to build frequency modulator with the help of wein bridge oscillator or any RC oscillator
so we should change op amp to faster LM324.
what is that green graph spikes in your pic.
Click to expand...

Its the resistance of R4.... V(x)/I[R4]
 
hello can you tell me how to start wein bridge oscillator quickly. currently it is taking 1.2 seconds to reach its maximum amplitude
 
neptune said:
hello can you tell me how to start wein bridge oscillator quickly. currently it is taking 1.2 seconds to reach its maximum amplitude
Click to expand...

Hi,
Do you mean in simulation or on an actual circuit.?

If its a Si, use .IC like I have shown on the earlier posts.
 
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