Variable Interstice Pickup Prototype

[KhzDonut]

Those magnets are far too large (in cubic inches) for the purpose.

You are very correct, these were the first I tested and they were way too big. I ended up with and 3/32" thick by 1/4" diameter, but 1/16" thick worked fine too. I tried 1/32", but they seemed weak. I thought maybe it was because of distance from the strings, not necessarily strength. Beyond my experience or theoretical knowledge to know for sure, thought. But yeah, 1/8" and bigger were too big and just kind of odd in their string interactions.

[copperheadroads]

Really interesting concept ,great R & D ,Remember if you want a more traditional magnetic field with traditional poles but use the Neo magnets . this fits in place of a '187"x .5" bar magnet Just something to think about . \m/:]

[KhzDonut]

this fits in place of a '187"x .5" bar magnet

That's kind of freaking genius, right there.

My most current prototype (not listed in this thread) has a steel plate bonded to the back of the magnets, bridging the gap between them. It had some good and bad effects on things, and I wonder if it would be reasonable to take the design in your photo and replace the wooden spacer with steel, and maybe much smaller magnets.

I'll tell ya, the worst thing about this forum is all the new ideas it gives me. I have no shortage of ideas, but a huge shortage of time and resources, so going down this rabbit hole just sends me deeper into madness I fear

[Joe Gwinn]

You are very correct, these were the first I tested and they were way too big. I ended up with a 3/32" thick by 1/4" diameter [magnet], but 1/16" thick worked fine too. I tried 1/32", but they seemed weak. I thought maybe it was because of distance from the strings, not necessarily strength. Beyond my experience or theoretical knowledge to know for sure, thought. But yeah, 1/8" and bigger were too big and just kind of odd in their string interactions.

The strings are not the main issue, as they are a tiny part of the magnetic circuit, most of which is non-ferrous, air or its moral equivalent. Although one can reduce the odd effects by moving the strings away from the pickup.

But it sounds like the 3/32" is still too thick, and 1/16" is best. One can also reduce the effective strength of the magnets by shorting out part of their field with a ferromagnetic shunt of some kind, so long as the ferromagnetic material does not saturate.

It may be useful to model your system using FEMM: http://www.femm.info/wiki/HomePage