Not exactly, but i want to make an oscillator that has 50kHz and amplitude output vary from 5V to 10V peak to peak. I don’t know how to make the output amplitude to vary in those limits

Here is an amplitude stabilization method which allows selectable amplitudes (symmetrical variation of the supply voltage divider chain)

 

And if i want to use an jfet instead the diodes?

 

Set it to 10V and put a pot on the output?

 

But with OPA621? I managed to obtain a 50kHz frequency with Wien bridge. But i don’t know how to change the amplitude from 5 to 10V

You can't do it by adjusting any of the components of the oscillator circuit. You can design the circuit to produce an output of 10 Vpp, run that signal through a potentiometer acting a volume control, and take the signal from the wiper through a unity-gain buffer like a voltage follower.

ak

 

The maximum slew rate of a sine wave (at a zero-crossing) is 2 x pi x f x Vp. In your case this is 1.571 V/us (volts per microsecond). An LM741 has a typical slew rate of 0.7 V/us, so it cannot work as either the oscillator or the buffer. It could work as the oscillator at a much lower output voltage, but then you would need an even better opamp as the output stage because it now would have to supply gain. Better to choose one opamp that can do both jobs, maybe a dual part to save cost.

The OPA621 certainly is good enough to work in both circuits. The NE5532 is another old and reliable part with gain, noise, distortion, and slew rate specs that are much better than the 741. Most geezers regard this as the first true "audio opamp".

ak

 

The OPA621 certainly is good enough to work in both circuits. The NE5532 is another old and reliable part with gain, noise, distortion, and slew rate specs that are much better than the 741. Most geezers regard this as the first true "audio opamp".

ak

Long live the 5532

 

For you young'ns out there, the NE5534 was the first real "audio opamp". It is compensated for gains down to 3, not unity. This and other design features give it a gain-bandwidth product that was three to four times that of other parts at the time. It is hungry, but that extra power draw gives it an exceptionally quiet input stage and basically zero crossover distortion in the output stage. And, that output stage can deliver +22 dBm into 600 ohms. It was relatively expensive, and a broadcaster's dream part. Later came the 5532, a dual version that is compensated down to unity gain. This gave it a more universal usefulness, and it still is hugely popular today.

My first dynamic mic preamp used two 5534's, built on perf-board in a Bud-box. The first stage was a fully differential amplifier (to eliminate an input transformer) with about 35 dB of gain and a single adjustment to tweak the common mode rejection. Next came an L-pad cough switch based on PhotoMod LDRs with incandescent light bulbs (clickless!). Last was the output driver, with 20 dB of gain adjusted down to about 12 dB, driving a 600:600 output transformer. This stage had a sculpted frequency response to match the microphone type and booth acoustics. The preamp ran in a TV station announce booth from 1974 to 2003.

ak

 

My first mic preamp used the 5534, built on perf-board in a Bud-box. Sculpted frequency response to match the microphone type and booth acoustics, PhotoMod L-pad cough switch. Ran in a TV station announce booth from 1974 to 2003.

ak

Mine was the mic preamp in a disco console. I switched it on and it buzzed like anything. It was shortly after that I first found out that, unlike DIN plugs, the middle pin on an XLR isn’t ground.

 

Once you figure out that pin 1 is GND (!!!), there are two options for wiring a balanced pair. Which pinout did you use? IOW, which pin was the "in-phase" signal? We used the CBS standard, with pin 2 out of phase and pin 3 in-phase. This was called "the hottest is the highest".

ak

 

That was about 40 years ago! I use "pin 2 hot" which is considered to be the European standard, pin 3 hot is the American standard, or so we think over here! For most purposes absolute phase is not that important. Unless you have an an assortment of mics, it probably won't matter.
I note that Neutrik (and probably everyone else) make the female connectors with the contacts on pin 1 further forward so that the ground connects first.

 

130 years ago Max Wien invented a Null bridge for measuring audio frequency, he was knowlegeable about adjusting it slightly off null.
With only an earpiece it was an excellant test instrument that had most influence in development of audio amplified bridge.
Both Wien and Barkhausen employed a feedback block and amplitude block depicted orange and green below. In the Wien frequency meter
below the circle represents an earpiece that was used as a null indicator.
Later the earpiece was replaced by an amplifier; vacuum tube, transistor or opamp.




Since a Wien Bridge oscillator differs from a frequency bridge ( the amplifier model mentioned in an earlier post was also elaborated on gain ect ).
The CA3130 works well using closely matched 1% resistors or better, high tolerance polystyrene capacitors would improve the quality of the sine wave. The slew rate, higher gain and input impedance makes a difference.
https://pdf1.alldatasheet.com/datasheet-pdf/view/66328/INTERSIL/CA3130.html

I think amplitude comes up at different stages of development, from quality aspect amplitude control can be addressed after the bridge is balanced close enough to entertain having both negative and positive portions of the sine wave centered precisely over the zero axis, then the in-phase relationship finally the gain control in order to drop the THD. The quanitative description of this oscillator can be broken down such that the left side can be concidered a feedback block and the right side (the resistive side) can be concidered an amplitude block.
*Reference to feedback mechanism (block) and the amplitude block the gain also described in the video.