[sdiy] What is a quadrature oscillator good for?

[Grant Richter]

I have been doing a lot of digging in the local public library for odd-ball
waveshaper ideas.

I found an interesting simple waveshaper to generate a quadrature signal
from a triangle oscillator core. It's from an old Electronics magazine
article (70s). I will put it up when I get a chance.

Aside from frequency shifters and qudraphonic panning, is there anything
else a quadrature oscillator is good for?

I am prototyping a linear through-zero quadrature LFO to use with the
Joystick Axis Generator (reverses panning direction with negative voltage),
I am curious if there are any other non-proprietary applications people
would share?

Also, are there other quadrature LFO designs out there? So I can properly
credit references.

Thank you for any help.