1. key, magneto-electric A telegraph key whose movements operate what is virtually a small magneto-generator, so as to produce currents of alternating direction, one impulse for each motion of the key. It is employed for telegraphing without a line battery, a polarized relay being used. In one very simpleform a key is mounted on a base with a permanentmagnet and connected to the armature, so that when the key is pressed downwards it draws the armature away from the poles of the magnet. If the magnet or its armature is wound with insulated wire this action of the key willcause instantaneous currents to go through a circuit connected to the magnet or armature coils.
Definitions of key, magneto-electric
