The Wien-bridge oscillator’s positive feedback circuit is

The Wien-bridge oscillator's positive feedback circuit is a part of the oscillator that amplifies a signal or process that encourages the occurrence of a given phenomenon or process. In the context of the Wien-bridge oscillator, the positive feedback circuit is designed to sustain oscillations.

Here are the steps to understand it:

1. The Wien-bridge oscillator is a type of electronic oscillator that generates sine waves. It can generate a large range of frequencies. The oscillator is based on a bridge circuit originally developed by Max Wien in 1891 for the measurement of impedances.

2. The bridge comprises four resistors and two capacitors. The positive feedback circuit is usually implemented with a tube, transistor, or operational amplifier.

3. The purpose of the positive feedback circuit in the Wien-bridge oscillator is to ensure that the amplitude of the oscillations remains constant. It does this by feeding back a portion of the output signal to the input, but with a phase shift that adds to the input signal, reinforcing it.

4. The feedback fraction must be set just right: too much feedback and the circuit will become unstable and produce a distorted signal, too little and it won't oscillate at all.

5. The positive feedback circuit is therefore crucial for the functioning of the Wien-bridge oscillator. It ensures that the oscillator starts up and continues to operate, producing a steady, undistorted sine wave.