I just got the magnet wire I ordered in the mail, and I'm waiting on the shim control boards now.

Properly winding the humbucking sensor coil pair requires matching the inductances of the two counter-wound coils to a reasonable level of precision. I decided to use the PyPPM hardware as an advantage here: I wrote a small OpenGL program to hook into the core PyPPM C API and continuously read out samples from the analog signal chain to produce a live-updating spectrum.

You can see a quick demonstration video below.

The result is pretty cool, and I can use the software (called 'liveft' in the PPM sources tarball) to check inductance matching while I wind the new coils. Ideally, when the coils are well-matched, any common-mode interference that would be picked up by a single-ended coil will be minimized.