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# Design of wien bridge oscillator

#### wien

##### Newbie level 6
Hello. I'm trying to design a circuit that outputs a Wenbridge oscillator that outputs 10V, 2V, 110khz, how do I get the resistance and capacitor values? And is there a related blueprint?
I've tried several times and failed, so I'm asking you a question. Thank you for reading

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Since R1 and the Lamp are grounded, that is only for bipolar supplies and Op Amps that have enough current to heat up a tiny lamp with say 1/4W.

This is not a practical oscillator for all Op Amps and not a very good oscillator since it needs a lamp to create gain regulation without the room temperature affecting the design.

The Wien bridge has 0 phase shift and an attenuation of 1/3. Thus with a non-inverting gain of 3 and inverting gain of 2 to just make it oscillate.
The Lamp being Rf/2 when warm will be higher gain at room temp, thus the soft limit to a sine wave.

Your challenge is to use an amp. that can drive enough current to make a lamp warm by the amplitude of square wave signal across it and change resistance enough to regulate a sine wave and not be affected by the room temperature because if the total loop gain is < 1 it stops working and if the gain is 10% higher than 1 you have clipping with 10% distortion. You can replace the lamp with a PTC resistor in the range that will produce 1/4W and make Rf twice the value when the PTC is warm.

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Even with the incandescent bulb stabilizer, it's still finicky to adjust the system to settle at producing a sine wave. Since you say you've tried I'll add my experience with a simulator (see below).

You previously specified 2 Amperes, therefore I put a 3.9 ohm resistor for the load. It's not necessarily a conventional place to put the load but it makes for a simple appearance and it turns the bulb visibly yellow which is nominally 6V and 10.8 Watts. A lot of experimentation is required to stabilize the output waveform so it does not clip (gain too strong) nor fade (gain is insufficient).

I don't understand why you have so many Wien Oscillator requests and changes to parameters.
Why do you want a pure sine wave to power a light bulb to stabilize gain when there are easier ways?

I wonder if "10V, 2V" is a typo and actually means "10V, 2A" as in previous posts? If so, question of suitable power amplifier adds to basic Wien bridge dimensioning and magnitude control problem. Other than suggested by previous posts, there's however no reason to implement oscillator and power amplifier in one stage. It's simple and in case of doubt more stable to separate both functions.

Regarding classical incandescent lamp PTC stabilization, it's a possible solution but requiring design skills and availibility of suitable miniature lamps. Today it's more a retro design (in remembrance of Hewlett-Packards first commercial product) than first choice. Nevertheless links above are teaching how to design it if you prefer it for some reason.

Choice of magnitude stabilization method depends also on accuracy and THD requirements which haven't been told yet.

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Can you recommend a suitable opamp for this?
It depends if you want rail to rail otherwise no matter, for my design.
For yours, forget it.
The resistors must be perfectly matched otherwise the 10k1 must be tuned to barely oscillate.
It is not a practical design to build. There are better designs

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