This generates very low-distortion sine waves up to 1V RMS,this oscillator operates over the range 16 to 22000 Hz.There is no settling time when the oscillator’s frequency is changed and no bouncing of the output waveform. Use of an expensive and sometimes difficult to obtain thermistor is avoided
The circuit is based on two articles that have appeared earlier in Wireless World – Roger Rosens’ “Phase -Shifting Oscillator”, February 1982 pp. 38-41, and J. L. Linsley Hood’s “Wien-Bridge Oscillator with low harmonic distortion” from May 1981.
This design features the simplicity of the Rosens’ circuit but avoids the use of a thermistor. Instead, oscillator stability is controlled by means of a common photo-resistor driven by a LED, as suggested in the Linsley Hood article.
Output voltage: Sine wave, 1V RMS max.
Total harmonic distortion @ 1V RMS output:
100Hz = 0.0035%
300Hz = 0.0028%
1kHz = 0.002 %
3kHz = 0.002 %
10kHz = 0.001 %
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