A magneto is an #electricalGenerator that uses #permanentMagnets to produce periodic pulses of #alternatingCurrent. Unlike a #dynamo, a magneto does not contain a #commutator to produce #directCurrent. It is categorized as a form of #alternator, although it is usually considered distinct from most other alternators, which use #fieldCoils rather than permanent magnets. Hand-cranked magneto generators were used to provide ringing current in #telephone systems.