Phase shift oscilltor using 741 op amp

[neptune]

hello i am posting my simulation here, please check whats wrong with it ?

 

[ericgibbs]

hello i am posting my simulation here, please check whats wrong with it ?

hi,
If you examine the circuit closely you will see that the 3, 10K's are in series with the 55.2K, the circuit will not oscillate.

Look at this pdf for an alternate way of creating a phase shift osc.

My best advice would be to use a modern OPA, the 741 is just going to cause your grief with the project.

 

[neptune]

hey that file you posted is not working, LTspice hangs

 

[ericgibbs]

hey that file you posted is not working, LTspice hangs

Runs on my PC.

EDIT:
As requested asc file added

 

[neptune]

and ya this is also pretty lethargic oscilltor takes full 1 second to start, please give me some sine wave oscillator which is quick to start.

 

[crutschow]

and ya this is also pretty lethargic oscilltor takes full 1 second to start, please give me some sine wave oscillator which is quick to start.

Picky, picky. Most oscillators require some time to reach steady-state operation. Why do you need an oscillator that starts fast? If you need an instant signal, then you turn the oscillator on ahead of time and gate the output to give the signal when you need it.

 

[ericgibbs]

and ya this is also pretty lethargic oscilltor takes full 1 second to start, please give me some sine wave oscillator which is quick to start.

hi neptune,
Look at this version sine/cos, starts up fast.

Its more complicated than that awful 741 OPA version.

 

[neptune]

ok but this also works right. do you know how to make its frequency low, whats formula, i think this circuit has low distortion and perfect sine wave.

 

[audioguru]

Eric, your sin-cos oscillator has a dual polarity supply then why is it biased at +4.5V instead of being biased at ground?
What stops the output from clipping?

Neptune, your RF oscillator is a Colpitts type that is used in cheap little FM transmitters. Its LC tuned circuit and C3 determine its frequency.
You have the LC tuned to about 500MHz but the very high value of C3 is for a much lower frequency. C3 is 4.7pF to 10pF in an FM transmitter.

 

[neptune]

yes i know its FM oscillator , but i want a simple cheap sine wave oscillator which is quick to start !
AG you havent told me whats the formula for its frequency

 

[audioguru]

yes i know its FM oscillator , but i want a simple cheap sine wave oscillator which is quick to start !
AG you havent told me whats the formula for its frequency

A formula for high frequencies is useless because the wires have unknown series inductance and the wiring has unknown parallel capacitance.

If you use a huge expensive inductor (that might pick up mains hum) and a pretty big capacitor then the formula is:

 

[neptune]

which is the most good sine wave oscillator you will recommend which is quick to start !

 

[IC-frier]

ritesh KAKKAR, U can use a bridge rectifryr

 

[neptune]

ritesh KAKKAR, U can use a bridge rectifryr

what is this ?

 

[alec_t]

A bridge rectifrier is an overheated bridge rectifier

 

[SgtWook]

Have a look at this application note from Texas Instruments:
https://www.electro-tech-online.com/custompdfs/2011/10/sloa087.pdf
It covers several different sine wave oscillators with discussions of strengths/weaknesses of the circuits, and formulas to assist you in calculating components to get your desired output frequency.

Consider the quadrature oscillator on pages 15-19 to 15-20; it's pretty simple, will start quickly and has both sine and cos outputs.

 

[neptune]

Have a look at this application note from Texas Instruments:
https://www.electro-tech-online.com/custompdfs/2011/10/sloa087-1.pdf
It covers several different sine wave oscillators with discussions of strengths/weaknesses of the circuits, and formulas to assist you in calculating components to get your desired output frequency.

Consider the quadrature oscillator on pages 15-19 to 15-20; it's pretty simple, will start quickly and has both sine and cos outputs.

after seeing this PDF only i decided to make oscillators, but i didnt knew they were very lithargic to start, now i am gonna try quadrature oscillator as my last attempt