This circuit fun video presents the Twin-Tee op amp oscillator - a fun circuit that can make low distortion (low THD) sine waves with simple resistors and capacitors, no inductors. It is a circuit you don't see written up too much.
Here is a link to the Texas Instruments article shown in the video:
http://www.ti.com/lit/pdf/slyt164
More appnotes on sine wave oscillators...
https://www.ti.com/lit/SLOA060
https://www.ti.com/lit/an/snoa665c/snoa665c.pdf
My show notes:
http://www.qsl.net/w2aew/youtube/twintee_oscillator.pdf
Related FFT and THD videos on my channel:
https://youtu.be/oRf-IpG6XAw?si=eM0TJF6JYi-yLC7k
https://youtu.be/s_cVP5gu4SY?si=rsxHSVUB_6KL4tEM
https://youtu.be/EqRvUyPhbu8?si=1AgOOXLWbkq-W_3U