In the beginning when I did not understand the physics behind magnetic pickups and didn't really expect an unmodified coil to give any usable signal above the noise level I just wanted to run some tests to find out what were the optimal positions and orientations of coil and magnet around the string for the loudest output.

I took a random tiny relay, connected it to my headphone amp, turned the gain all the way up, stood in front of my wall of guitars and plucked different strings while placing the relay next to them in the vicinity of the magnetic field of already installed pickups. I also played a little with neodymium magnets and was surprised by two facts: I don't always need all the gain to clearly hear the sound, and I don't always need external magnetic field at all!

So it was on! I decided I don't need to do anything to the relays in order for them to work as pickup coils.However I need to do more experiments with oscilloscope and get better understanding of how magnetism works.