Low Distortion Wien Bridge Oscillator

This Wien bridge oscillator uses incandescent lamp to stabilize its amplitude. This amplitude stabilization gives a low distortion output.  Multiple frequency range selector gives flexible and fine adjustment for the frequency. Here is the schematic diagram of the circuit:

The 20k potentiometers is a dual channel pot, which is commonly used in stereo audio circuits. You can many types of op-amps, and many modern op-amps would even give better performance, especially at high frequency ranges. [Circuit’s schematic diagram source: lh-electric.4t.com]