String instrument strings, or play them by rolling the bell of a brass instrument such as a trombone on the array of strings. However, these are relatively rarely used special techniques. Other keyed string instruments, small enough for a strolling musician to play, include the plucked autoharp, the bowed nyckelharpa, and the hurdy-gurdy, which is played by cranking a rosined wheel. Steel-stringed instruments (such as the guitar, bass, violin, etc.) can be played using a magnetic field. An E-Bow is a small hand-held battery-powered device that magnetically excites the strings of an electric string instrument to provide a sustained, singing tone reminiscent
Hurdy-gurdy outside the keybox. They also generally have more strings and doubling or tripling of the melody string is common. Some modern instruments have as many as fifteen strings played by the wheel, although the most common number is six. In pop music, escpecially in the popular neo-medieval music, electric hurdy-gurdies are used, wherein electro magnetic pickups convert the vibration of its strings into electrical signals. Similar to electric guitars, the signals are transmitted to an instrument amplifier or reproduced by synthesizer in a modified form. Electronic hurdy-gurdies, on the other hand, manage completely without strings. The signals for the melody