Physics Question #24

Willi Luke, a 18 year old male from the Internet asks on June 6, 1999,

I am currently doing research on the e-bow, a guitar effect that calls upon an infinite feedback loop to produce infinite sustain by keeping the string in constant vibration. However, I am baffled as to the internal components and devices that drive this implement. I hypothesize that it has a huge frequency which enables it to activate strings of variable widths, however, I am still puzzled as to the schematics. Coil type? magnetics?

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The answer

Barry Shell answered on June 6, 1999

The following website ( explains it as an "electromagnetic design, involves holding a battery operated device that looks like a stubby, metallic check mark, in close proximity to the strings, near where you'd usually hold a pick. The electromagnetic vibration is strong enough to make the string vibrate by carefully holding the device right next to the string." Also, the manufacturers of the e-bow have their own site ( which has a lot of information on how it works, but obviously they don't give away their trade secrets. You might also try the Delphion Intellectual Property Network page ( - now available by subscription only) which provides access to the whole patent, complete with the electronic schematic.

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