Magneto

A hand crank is actuated by hand or with the feet of electrical generator ( dynamo). It is operated by turning a crank or a Fußpedalantriebs (referred to as Tretgenerator ). With the drive by a laminated iron armature is basically rotated by a horseshoe magnet in the device on which a copper coil is applied from about 4000 to 8000 turns. By the moving magnetic field, an alternating voltage generated in the wire coil by electromagnetic induction. Find application Kurbelinduktoren for example, in telecommunications, for generating test voltages and blasting machines to trigger explosions.

Telecommunications

A hand crank is used in telephone sets in the local battery operation for generating the ringing voltage. This ringing voltage can be addressed to the other party ( mediation or another phone ) a visual display (symbol, signal lamp, case flap on a switchboard ), or an alarm clock. Such a hand generator delivers an alternating voltage of 30 to 100 volts at a frequency of 15-25 hertz. For the power supply of the actual conversation of the hand generator is not suitable with its AC voltage, it is near the phone, a DC voltage source, which requires " local battery ".

The technique was used in the marshals of the train to the end of the 20th century; with mechanical interlocking, it is used to this day. In military and civil protection (THW, fire, ambulance, etc.) Kurbelinduktoren continue to be used in simple field telephones. Another application is the Crank insulation measurement.