One of my customers brought in this Gibson L-50 wanting to add a pickup but without modifying the guitar and without external wires. Drilling for and endpin jack was acceptable so the challenge was to make pickup thin enough to fit under the strings and mounting it without drilling into the top or fretboard.
To keep the pickup thin I decided that the pole pieces would need to be magnetic rather than mounting the magnet underneath. I don’t have access to short Alnico magnets so I decided to use 1/8″ diameter by 1/4″ rare earth magnets. I machined brass cylinders to hold the magnets and give a more traditional humbucker look and to stagger the polepicese. The bobbins were made with a clear acrylic core and tortoise celluloid top and bottom to match the pickguard. I wound the bibbins with 5000 turns of 43 gauge wire giving an output of 11.5k.
To mount the pickup I made a copy of the existing pickguard that has an extra extension to surround the pickup and mounted a volume and tone thumbwheel pots underneath. The wires from the pickup run behind the pickguard and into the f-hole and out the endpin jack.
I am very pleased with the outcome. The pickup sounds good and the output i well balanced.