Wien bridge oscillator

set simspeed to 40us/s because you expect 26.6kHz and give it more gain e.g. 2.02kOhm@40us/s instead of 1.5kOhm. This is to get 3+ total gain. Anyway it will go into clipping sooner or later. Checkout some more discussion here on EC

Change value of capacitor to 1mf and it starts producing square wave

Or change the sim speed to 20us/s .because 25khz freq = 1/(25*1000) sec = 40us so it will give better view at 20us/s simulation speed. :-)

Your oscillatory vlktage will will die in 40us * (600ohm/200uV)=120 uS . So at sim speed of 20 us/s you can see it upto 120/20 = 6 sec instead of at sim speex of 1s/s in which you can see only fir 6us .. which is very small. :D

Yes i got it. When i changed r value from 1.5k to 2k and simulation speed from 1s to 20us then shake it, circuit was oscillating thanks a lot guys i missed the values :)

Instead of changing 1.5 to 2k change 600ohm to 300ohm . It will give better oscillation at 20us sim speed with less power consumption and less cost . :D

You are welcome. Observe what happens with 2k to 1k gain="3" which is actually not exactly 3. It a little less 3

Owk so you are considering gain 1+Rf/Rb = 1+(2/1) = 3 . Owk tell me one thing why we can not find gain from negative terminal of op amp . Since by sane terminal voltage and same output voltage we should have same gain .. ?? It is just a question . If you know then explain . :-) :D

I found examples and approaches from these type circuits. There is a criteria in here Berkhausen criteria. this criteria says that rf/r1 = 2 in order to adjust sinusoidal signal which is in chose frequency by capacitors and resistance. On the other hand capacitor and resistance values in circuit is so small that (there tao's are also small) oscillation voltage is too small. In order to see Adjustible output voltages, we must wait too long. Bla bla bla... shortly, we must increase input resistance value and also rf value from barkhausen to see output in short time :) i choose 250k and 100k and build in pc program. it works :) but ec is cannot find solution. Np for me thanks anyway.. :)

Where is sqrt in your formula? 25 kHz= 1/ 2pi sqrt (LC). Not RC time constant calculation.

@kyacn it is working here but you have make sim speed 20us/s and adjust ofest voltage of opamp in order to get sinuoid. @lmccoig it is wien circuit oscillator . Hete sine two resistances and two capacitances in down branch its w²=1/(R1R2C1C2) now when R1=R2 =R and C1=c2 =C w²= 1/R²C² now freq f=1/2piRC. :-)