You probably have seen it, a small black cylindrical item encircling your old laptop charger cord, close to the connection. Some folks might view it as excess plastic, a handle, or a design anomaly. However, the little cylinder is really there to perform an important task.
The small cylinder is called a ferrite bead or ferrite choke. What it does is filter out unwanted “electrical noise” in the form of high-frequency interference. In essence, it stops the charger from acting as an “antenna,” radiating unwanted signals and/or receiving interference from the environment.
It isn’t cosmetic and shouldn’t be removed.
What Is the Ferrite Bead Composed Of?
Inside the ferrite bead’s casing is typically ferrite material, a ceramic-like material utilized to suppress electromagnetic interference in electronic systems.
Your charger is a switching power supply. This converts AC power from your house outlet into DC power for your laptop. To accomplish this conversion, the charger rapidly switches the flow of current on and off. As a result, it is smaller and more efficient than traditional linear supplies. However, these rapid changes in current create unwanted electrical “noise.”
While not generally harmful to humans and not indicative of charger malfunction, this unwanted electrical “noise” affects electronic systems. The ferrite bead assists in managing this unwanted “noise.”
Why Is the Ferrite Bead Located at the End of the Charger Cable Instead of Being Integrated Into the Charger?
Any electronic cable can act somewhat like an antenna. When unwanted electrical “noise” enters the charger cable, the unwanted signal can radiate outward from the cable. Additionally, unwanted electrical signals from neighboring electronic devices can enter the cable through radiation and travel toward the laptop.
Therefore, placing the ferrite bead at the end of the cable, near the laptop connector, helps manage unwanted “noise” both entering and exiting the device.
There are times when you may not appreciate the importance of reducing unwanted electrical “noise” in your electronics. Interference can occur with radios, speakers, computer screens, Wi-Fi devices, etc. Many times, you may never recognize that anything is going on. This is what the ferrite bead is intended to do: mitigate potential problems before they become noticeable or annoying issues.
How Exactly Does a Ferrite Bead Operate?
Simply put, a ferrite bead filters out high-frequency “noise” while permitting normal operation of the charger. As long as your laptop receives sufficient power, unwanted high-frequency “noise” is minimized.
Think of it like this: the power delivery through the charger cable contains desirable power as well as potentially undesirable high-frequency “clutter.” The ferrite bead acts to minimize this “clutter.”
Does it store energy? No. Does it speed up charging? No. Does it provide protection against all possible surges? And no. It primarily exists to reduce EMI (Electromagnetic Interference) and RFI (Radio Frequency Interference).
Is a Ferrite Bead Considered a Safety Feature?
While it provides additional protection for your electronics, it doesn’t exist in the same manner that fuses, surge protectors, or circuit breakers do.
The primary purpose of a ferrite bead is to ensure compliance with EMI standards. It also assists in minimizing unwanted interference around your electronics. This benefit extends to the charger, laptop, and other nearby electronic systems.
However, if your charger’s cord becomes damaged (frayed, cut, exposed, bent, sharply bent, etc.), a broken ferrite bead does not eliminate your need to replace the entire charger.
Can I Remove Mine?
No, it’s best left alone.
Removing a ferrite bead will not likely cause your charger to cease functioning immediately. However, it could increase electrical noise. Removing a ferrite bead improperly could even damage your cable.
Even if the casing covering the ferrite bead is cracked but remains functional on your charger cable, there is no guarantee that the charger will continue to work. Continue to monitor your charger for any indication of exposure (exposed wires, loose connections, excessive heat, sparks, etc.) or charging issues.
Regardless of what damage occurred to your original charger cord, always obtain a replacement charger rated for your laptop.
Why Don’t All Laptop Chargers Come Equipped With a Visible Ferrite Bead?
Newer chargers could possibly utilize advanced internal filtering techniques or shielding capabilities incorporated directly into their designs. Thus, they may eliminate the need for an external ferrite bead.
For example, newer USB-C chargers tend to appear less cumbersome compared to older barrel-style chargers. That doesn’t mean that they lack adequate noise reduction. Possibly, newer designs either include internal ferrite beads or utilize alternative noise-reducing technologies. These are contained within the design of their power bricks or cabling.
Other chargers incorporate their ferrite beads internally into sections of their cabling. Still others do not require an external ferrite core because their existing design meets EMI standards without needing additional components.
Therefore, if your charger does not contain a visible ferrite bead, this factor by itself does not constitute an issue. Rather, it would be more critical to determine if your charger matches the specifications required for your laptop. Also, check if it was manufactured by a reputable company, and if the charging cable is free from physical defects.
Why Are They So Large and Awkward?
Ferrite cores must completely envelop the cable in order to successfully suppress EMI. Due to this requirement, they are frequently depicted as lumps or barrels around the cord.
The raised surfaces found on many external casings are merely for aesthetics, meaning they are not necessarily intended to provide mechanical grip or enhance airflow.
If you plan on storing a charger away after extended use periods, please refrain from coiling your cord tightly around your power brick, particularly where the plug or ferrite bead is located. Tightly coiled loops may degrade your cord over time. Since areas near connectors represent the most typical points of charger degradation during storage, loose coils are preferable.
Does a Ferrite Bead Impact Charging Rate?
The ferrite bead will not accelerate charging rates, nor will it impede normal operation when your charger functions properly.
Charging rates depend upon factors including the watts provided by your charger, the power requirements of your laptop’s battery at a given moment, the general health of your battery, operating temperatures of your system, and whether or not you’re utilizing your laptop while charging.
Essentially, a ferrite bead merely assists in minimizing unwanted electrical noise traveling along your charger’s cabling.
If you experience slow charging, it is virtually guaranteed that neither the ferrite bead nor other factors related to your charger’s design contributed to slowing your charging process. Verify that you’re utilizing the properly rated charger specifically designed for your laptop. Also, inspect whether the connector fits securely into your laptop.
Also verify whether there is evidence indicating physical or thermal damage to your charger or port.
Do You Need to Attach Another One to a Non-Ferrite-Beaded Charger?
Generally, no, unless you’re experiencing specific problems related to interference.
Clip-on ferrite cores can be purchased separately to aid with noisy applications, such as buzzing audio devices or RF interference affecting communication equipment. However, attaching an additional clip-on ferrite core is seldom warranted unless you are actively troubleshooting an unrelated problem.
When purchasing a new charger for replacement purposes, prioritize obtaining a compatible charger based on wattage, voltage, connector type, and manufacturer. The existence of a visible ferrite bead is secondary to ensuring that your new charger meets these criteria.
An Unobtrusive Component With a Quiet Mission
That small cylinder attached to your laptop charger isn’t just additional plastic. It’s called a ferrite bead, and it aids in reducing EMI caused by interference generated by your charger, laptop, and neighboring electronic devices.
Since it performs its task quietly, few users consider it at all. Your charger powers your laptop, appears normal, and the ferrite bead helps keep unwanted EMI from becoming a problem.
So, that small cylinder on your laptop charger serves as a tool for reducing unwanted electrical noise throughout your electronic systems. Leave it alone. Treat your cable with care. Replace damaged chargers!
