As part of this project, I need to find a way to capture the individual tones from each string, and do it in a way that doesn't interfere with the "natural" way the banjo is played. As I mentioned in my last post, this is done by a pickup, but I need one for each individual string. Normally these seem to be coils, but I'm going to try to use a device called a hall effect sensor that, with the help of a strong magnet underneath, should detect the resonating string. Many hall effect sensors only tell you "on" and "off," but I'm looking for a radiometric hall effect sensor that will give me an analog signal that will represent the string movement. The ones I'm looking at right now are the Allegro A132X series sensors, which I believe will do the job. Some experimentation is needed however, since I don't know how strong of a magnet will be needed or what the exact placement will need to be.
My next step is to mock up a couple of strings, magnets, and sensors to see how it behaves. Why two? Because one of the main goals of having a single string pickup is isolation, and I need to know how much noise bleeds into adjacent sensors.