Tuning of musical instruments

Claim 1

Apparatus arranged to automatically vary the pitch of a string, said apparatus comprising: a string having first and second spaced ends; an adjusting mechanism coupled to said first end of said string; and anchoring means for anchoring said second end of said string: said string being stretched and tensioned between said adjusting mechanism and said anchoring means; said adjusting mechanism comprising a movable adjustment member to which said first end of the string is anchored; a drive motor; means for coupling said drive motor to said adjustment member such that rotation of said drive motor moves said adjustment member and thereby adjusts the tension of the string; detecting means arranged to produce a signal representative of the pitch produced by vibration of the string; comparing means arranged to compare said representative signal with a predetermined reference and to produce an output dependent upon said comparison; and means for applying the output of said comparing means to said drive motor to rotate the drive motor thereby adjusting the tension applied to said string in response to said output of said comparing means; wherein said adjusting mechanism further comprises resilient biasing means coupled to said movable adjustment member to bias said adjustment member in a direction opposing the tension of the; wherein said detecting means comprises pulse generating means for generating periodic pulses having a frequency representative of the pitch of the vibration of the string, and a counter receiving said periodic pulses and producing an output count representative of said pitch; and wherein said adjustment member comprises a screw-threaded member attached to said end of said string, and said means for coupling said drive motor to said adjustment member comprises one or more gears.