In an electrical circuit, a choke, also known as an inductor, is used to restrict higher-frequency current while passing direct current (DC) and lower-frequency alternating current (AC). The name derives from the fact that high frequencies are blocked, or "choked," while low frequencies flow through. Chokes are commonly used in power supplies, oscillators, and radio receivers to reduce the impact of noise on other parts of the circuit.
The most common type of choke is the metal oxide ceramic capacitor (MOC). These devices are efficient converters of DC to AC, compact, and inexpensive. They also have very low impedance at high frequencies compared to other types of capacitors. This makes them good attenuators of noise and interference.
The second type of choke is the toroid. These devices are shaped like a doughnut and consist of a core of magnetic material wrapped with wire. When current is passed through the wire, a magnetic field is created which causes the core of material to become magnetized. This creates a reaction against the source of current; thus, preventing any further current from flowing. Toroids are more efficient than chokes because they do not pass any DC current but are very effective at blocking high frequency signals.
The third type of choke is called a ferrite bead. These devices are balls or flat disks of ferrite material that contain multiple coils of wire.
The name derives from the fact that high frequencies are blocked—"choked"—while low frequencies are passed. It is a functional name; the term "choke" is used when an inductor is employed to block or decouple higher frequencies, while the component is simply referred to as a "inductor" when used in electronic filters or tuned circuits. The inductor used in these applications must have sufficient magnetic strength to block or attenuate the higher frequency signal without significantly affecting the lower frequency one.
Inductors can be made from wire coiled around a core material such as iron or plastic. The more turns of wire on the coil, the larger the inductance value will be. Coils with many layers of wires wound around a core produce large-value inductors that are relatively inexpensive and easy to make in quantity. Core materials with greater permeability (magnetic susceptibility) will result in smaller-valued inductors.
Chokes use two parallel-connected inductors to block high-frequency signals while allowing low-frequency signals to pass through. This type of circuit is useful for reducing noise from power lines or radio transmissions that contain high frequencies but not low ones. Chokes are generally made from wire wrapped around a ferrite core. The number of wraps determines the amount of reduction in gain at high frequencies.
The choke comes in different values depending on how much current it can handle.
A coil or inductor is used as an electrical choke. A choke is a conductor that has been coiled on a core with a number of turns. The electrical choke functions similarly to an inductor. However, it can be installed in a circuit board or other medium containing multiple paths for current. This allows the circuit to function even when some parts are not present or damaged.
Electric chokes are used where there is a need to limit the current flowing through a circuit component such as an incandescent lamp. An electric choke will reduce the voltage across the components of the lamp and thus reduce the power consumed by them. This can extend their life when used with components such as halogen lamps which are susceptible to burning out if operated at too high an average power level. Electric chokes are also used in power supplies to prevent current from flowing into any one side of a transformer more than necessary. This prevents excess heating in one area of the transformer and reduces the likelihood of damage to the device.
The word "choke" comes from the fact that these devices were originally made from pieces of wood with holes drilled in them, just like a wood chisel. They were then covered with leather or cloth and attached to a handle so that they could be used easily. These days, electric chokes are usually made from metal sheets or strips etched with the required pattern.
Because a choke is mostly employed to halt frequency, but an inductor has a variety of applications, including this one. A choke is nothing more than a sort of inductor. The primary distinction between a choke and any other form of inductor is that a choke has a ferro-magnetic core, which increases its inductance. Thus, a choke can both restrict current flow and increase voltage while still under load.
Inductors are used in many circuits to limit the rate of change of current with time or phase angle. This is usually done by inserting a capacitor across the ends of the winding or windings of the inductor. This forms a circuit known as a "LC filter", after the two components that make it up. By adjusting the value of the capacitor, the frequency response of the inductor can be changed significantly. For example, if the capacitor is replaced by a resistor, then the circuit becomes a high-pass filter which passes signals of low frequency while attenuating signals of high frequency.
The magnetic properties of metals such as iron allow it to function as a conductor at high frequencies while acting as a partial ground for those same high frequencies. This means that a metal object can act as a conductive path for current flow while also storing energy within its magnetic field. This is how inductors work at a fundamental level; they are the only devices capable of storing electrical energy.