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What is the purpose of a choke in electronics?
A choke, also known as an inductor, is used to block higher-frequency while passing direct current (DC) and lower-frequencies of alternating current (AC) in an electrical circuit. The name comes from blocking, or “choking”, high frequencies while passing low frequencies.
How do you do a common-mode choke?
The simplest way to make a common-mode choke transparent is to make it from a piece of the same type of cable. Then, to give the choke a high common-mode impedance, you surround this piece of cable with ferrite. Ferrite is a ceramic material, made like pottery or bricks, by firing in an oven.
How does a common mode choke suppress noise?
Noise Suppression by Common Mode Choke Coils. Common mode choke coils work as a simple wire against differential mode current (signal), while they work as an inductor against common mode current (noise).
How are common mode choke coils used in power lines?
Common mode choke coils are very useful in these types of applications. In common mode choke coils, no magnetic saturation occurs, as flux generated by differential mode currents cancels each other out and disappears. Common mode choke coils are therefore used to suppress noise in power lines through which large currents flow.
How does a CM choke block cm currents?
Thus, the CM choke inserts an inductance L + M in each winding, and consequently, it tends to block CM currents. Ideally, this total inductance should be very large over the entire frequency range. Equivalently, the common-mode insertion loss of an ideal CM choke should be very large over the entire frequency range.
How does common mode work on a DC power line?
Common mode current often enters the victim device via the AC or DC power lines to the device. Likewise, the RFI source device often conducts common mode current through the AC power line where it is picked up by the victim device. The AC or DC path must be choked to suppress the interference.