Air coils
A coil is mechanically nothing more than wound wire. A winding body, as Intertechnik usually uses, is not only necessary for production reasons but also guarantees an optimum and compact winding quality, regardless of the number of windings. The coil's mode of operation is based that a conductor through which an electric current flows generates a magnetic field generated. If the conductor is wound up, the coil is reached via the conductor loop to the coil. Inside the inside the coil there is a largely homogeneous magnetic field magnetic field B (T) (unit Tesla). When the direction of the current is reversed the direction of the magnetic field is also reversed.
A reversal, or constant change of the current, as occurs with music signals, results in a constant change of the magnetic field. magnetic field. Here the coil shows an interesting behavior: A changing magnetic field (change in flux density) causes induction voltage in the coil's own windings, which has a delaying effect on the generating change in current strength.
The faster the change in current direction occurs (high frequencies), the more pronounced this effect is. The coil then acts like a resistor. This alternating current resistance of a coil is also referred to as inductive resistance. The electrical quantity that describes the coil effect is the inductance inductance L (Henry unit of measurement).
In addition to the inductive resistance, the coil also has a further resistance resistance (direct current resistance or DC resistance), which results from the limited conductivity of the wound wire. An air-core coil can be largely characterized in the audio frequency range by the inductance L and the DC resistance Ro.
