im trying to build a sinewave generator using an RC oscillator with https://www.electronics-tutorials.ws/oscillator/rc_oscillator.html as a guide. i've done what the guide says like making sure i have at least 29V voltage gain and using 1/2pi(R)(C)(√ 2N) to get the resistance needed for my target frequency.

and yet when i set it up in multisim i'm getting enter image description here

the sinewave voltage went from mv to kv, to megavolts to Teravolts. i also did other oscillators like wein bridge, and even exactly copied working oscillator circuits and all of them produced either the same result or just a simple DC voltage.

pls help me


My recommendation: Don`t blindly trust such "tutorials".

The circuit diagram is wrong: The resistor R4 is placed directly across the opamp input nodes and thus, cannot provide the desired function. Instead it must be placed in series with C3 and the inverting opamp input.

More than that, the required gain must be slighly larger than "-29" (for example "-30...-32"). In this case, the oscillator can start rather safely.

More than that - be sure to use a realistic opamp model with amplitude limitations due to the fixed and finite power rails. In this case, the amplitudes will be "clipped" - unless you are using one of the available methods for "soft" amplitude limitations (e.g. two antiparallel diodes).


Simplistic sine wave oscillators like this are usually a disappointment when implemented because there is nothing that controls the amplitude of the sine wave. Sure, the RC networks (whether Wien type of phase shift type) fully define the operating frequency but nothing in your design sets the peak to peak sine wave amplitude.

Using a JFET as an amplitude controller is usually effective and so is limiting the signal with back-to-back diodes. Your circuit relies on the sine wave amplitude being set by the op-amp's output voltage clipping and, in a simulation, if the model doesn't have this feature (because it's well-down the to-do list for the modeller) then the output will reach stupid levels and you'll be left thinking that you have found a circuit using an opamp that can generate a tera volt or two.

If you read this question and answer you'll find more details about the amplitude problem and a circuit like this: -

enter image description here

The circuit uses a single transistor with transformer feedback but the principle is the same - if you do not have an amplitude control then you do not have amplitude stability and your sine wave purity can be rather poor.


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