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Since the 1950s, electric guitars have used 鈥渉umbucker鈥� pickups to turn the vibrations of a string into an electric current of the same frequencies and harmonics. Underneath each string, side-by-side magnets and coils wired in opposite directions sense the string vibration, but cancel a steady signal that carries on for a long time, such as mains hum. Some experts say this also cancels some of the musical harmonics and dulls the sound, so David Devers of Victoria, Australia, is patenting a better bucker (GB 2364594). Two rod magnets stand top to tail underneath each string, with an oppositely wound coil round each. The vibrating string affects only the flux for the top magnet, but the signal is relayed to the lower magnet by induction. This still cancels a steady mains hum, but leaves musical harmonics untouched to yield a purer sound.