What does a field coil do?
A field coil is an electromagnet used to generate a magnetic field in an electro-magnetic machine, typically a rotating electrical machine such as a motor or generator. It consists of a coil of wire through which a current flows.
Why does each field coil have a pole shoe?
As the rotor spins it induces current to flow within the stator windings, and the output is taken from the stator. In a dynamo, the field coils are fixed around the pole shoes. It is the armature that rotates and produces the output from the machine.
How is a magnetic field produced in a field coil?
A current through any conductor creates a circular magnetic field around the conductor due to Ampere’s law. The magnetic fields generated by the separate turns of wire all pass through the center of the coil and add (superpose) to produce a strong field there. The more turns of wire, the stronger the field produced.
Are field coil speakers better?
Remarkably, many audiophiles consider field coil loudspeakers to be sonically superior to models using Alnico or other magnets. Field coil drivers, with their own power supplies, do not exhibit these irregularities in strength and so have much less distortion than their permanent magnet counterparts.
What increases the magnetic field within an electromagnet?
The strength of an electromagnet can be increased by increasing the number of loops of wire around the iron core and by increasing the current or voltage. You can make a temporary magnet by stroking a piece of iron or steel (such as a needle) along a permanent magnet.
What kind of magnetic field is produced inside a coil?
Electromagnets
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole, denoting the center of the coil.
What is a speaker field coil?
A wire coil that, when charged with electrical current, produces a magnetic field. Field coils were utilized in early 20th-century loudspeakers, prior to their replacement by permanent magnets. Speakers are the primary source of distortion in the playback chain.