A switching device used to open an electric circuit when there is no current through it. They are used to isolate a part of an electrical system to allow the maintenance staff a safe access to it.
A device, electronic or mechanical, that helps a person tune a musical instrument by showing the deviation of the played pitch from the desired pitch.
A musical.
A person who tunes a piano or organ.
The component of an audio system that receives radio broadcasts.
On a musical instrument, a peg or mechanical device that changes the tension, and hence pitch, of a string.