When it comes to ferrite, there is a lot of terminology that can be difficult to understand – especially if you have limited knowledge of the subject. In this blog we aim to break down some of the key terms you should know in order to have a good understanding of ferrite’s properties and behaviours. Permeability (μ, mu) Permeability is a measure of how easily a material can become magnetised. It tells us how well a material responds to the presence of a magnetic field.   Imagine permeability as the material’s magnetic sensitivity. High permeability means the material readily responds to a magnetic field, making it easier to magnetise. On the other hand, low permeability indicates resistance to magnetisation. Unit of Measurement Henrys per metre (H/m) Initial Permeability (μi) Initial Permeability refers to the permeability of a material when it is first subjected to a magnetic field. It indicates how easily the material responds to magnetisation under initial conditions.   Think of Initial Permeability as the starting point for magnetisation. It represents the material’s inherent magnetic responsiveness before any external factors influence its behaviour. Amplitude Permeability (μa) Amplitude Permeability is the maximum value of permeability reached by a material when exposed to a varying magnetic field, such as in alternating current (AC) applications.   Consider Amplitude Permeability as the peak responsiveness of the material to fluctuations in magnetic fields. It reflects how well the material can maintain magnetisation under varying conditions. Coercivity (Hc) Coercivity, also referred to as coercive field or coercive force, is the measure of a material’s resistance to becoming demagnetised. It represents the amount of reverse magnetic field needed to reduce the material’s magnetisation to zero.   Think of coercivity as the material’s stubbornness to lose its magnetisation. High coercivity implies it takes a significant effort to demagnetise the material, while low coercivity means the material easily loses its magnetisation. Unit of Measurement Amperes per metre (A/m) Saturation (Bs) Saturation is the point at which a material cannot be magnetised any further. Beyond this point, applying additional magnetic force doesn’t result in increased magnetisation.   It’s like trying to absorb more water with a sponge that’s already saturated – there’s a limit to how much it can hold. Unit of Measurement Tesla (T) or Gauss (G) Curie Temperature (Tc) Curie Temperature is the temperature at which a material undergoes a phase transition, causing a significant change in its magnetic properties. Above this temperature, the material loses its magnetic capabilities.   Consider Curie Temperature as the “heat threshold” for magnetism. When a material is heated beyond this point, its magnetic behaviour transforms and it loses its magnetisation. Unit of Measurement Degrees Celsius (°C) or Kelvin (K) Magnetic Flux Density (B) Magnetic Flux Density, often simply referred to as flux density, is a measure of the strength of a magnetic field. It quantifies the amount of magnetic flux passing through a given area.   Imagine Magnetic Flux Density as the concentration of magnetic field lines within a specified region. Higher flux density indicates a stronger magnetic field, while lower values signify a weaker field. Unit of Measurement Militesla (mT) Core Losses (Pv) Core Losses, also known as iron losses or magnetic losses, refer to the energy dissipated as heat within a magnetic core when subjected to alternating magnetic fields. These losses occur due to hysteresis and eddy currents.   Core Losses are a crucial consideration in transformer and inductor design, as they impact the efficiency and performance of magnetic components. Unit of Measurement Kilowatt per metre cubed (kW/m³) Resistivity (ρ) Resistivity is a measure of a material’s inherent opposition to the flow of electrical current. It indicates how effectively a material resists the passage of electrical charges.   Think of Resistivity as the material’s reluctance to allow the flow of electricity. Higher resistivity means greater opposition to current flow, while lower resistivity implies better conductivity. Unit of Measurement Ohm Metre (Ωm) Understanding Ferrite’s Properties Whether you’re starting a DIY project, studying engineering, or simply curious about the world of magnetism, these foundational concepts can help you to understand ferrite and its magnetic properties. Now that you have a basic understanding of what these terms mean, we can start to explore the different ferrite materials and forms that are available, along with how they can be beneficial for particular applications. Want to buy ferrite? Visit our shop now to see what we have in stock! https://www.shop.gatewaycando.com/magnetics

If you have ever worked with electronics, or simply use electronic devices in your daily life, then it is likely that at some point you have come across ferrite – whether you have noticed or not! In the first part of our series ‘Ferrite for Beginners’ we explored why there is a need for ferrite, particularly when it comes to managing power efficiently. Now we are going to take a closer look at ferrite as a material itself, first exploring how it came to be, before looking at the different types of ferrites that are available. A Brief History of Ferrite 1930 – Discovery at the Tokyo Institute of Technology In 1930, the discovery of ferrite marked a significant milestone in the field of magnetic materials, attributed to the collaborative efforts of Dr Takeshi Takei and Dr Yogoro Kato at the Tokyo Institute of Technology in Japan. They discovered ferrite while conducting research on magnetic materials, with a particular interest in materials that could exhibit high electrical resistance and significant magnetic properties. World War II – Ferrite’s prominence During World War II, ferrite proved useful for various military applications due to its magnetic properties. It played a crucial role in the development of radar technology, serving as a key component in radar antennas. The development and deployment of radar technology during the war marked a turning point in the use of ferrite, transitioning it from a laboratory discovery to a critical component in military and civilian technologies. Post-War Era and Beyond After World War II TDK, Philips (now Ferroxcube), and other companies, including Fair-Rite and Magnetics, continued to innovate and refine ferrite technology. Ferrite became a fundamental material in the production of electronic components such as transformers, inductors, and magnetic cores. These components were integral to the growth of the post-war electronics industry, supporting advancements in telecommunications, computing, and consumer electronics. What is Ferrite? Ferrite is a type of ceramic material that is composed mainly of iron oxide (Fe2O3) combined with other metallic elements like manganese, zinc, or nickel. It is a type of metal oxide, and its name is derived from the Latin word “ferrum,” which means iron.   Ferrite is known for its magnetic properties, making it useful in various applications related to electronics and electrical engineering. It has a crystalline structure, and its properties come from the alignment of magnetic moments (the strength and direction of a magnet) in its crystal lattice.   Ferrites can be categorised into two main types: hard and soft ferrite. Hard and soft ferrites are types of magnetic materials that exhibit distinct magnetic properties, making them suitable for different applications. Let’s look at the differences between hard and soft ferrites, as well as some of their applications. Hard Ferrites Hard ferrites, also known as ceramic magnets or permanent magnets, are characterised by their high coercivity and remanence. Coercivity refers to the material’s resistance to demagnetisation, while remanence is the residual magnetisation retained when the external magnetic field is removed. These materials are commonly composed of iron oxide mixed with other elements such as barium, strontium, or lead. Hard Ferrite Applications Magnets for Electronics:  Hard ferrites are widely used in the production of magnets for electronic devices such as speakers, headphones, and microwave components. The stable and strong magnetic properties make them ideal for creating compact and efficient magnetic systems. Magnetic Separators:  Hard ferrite magnets are employed in magnetic separators for separating ferrous materials from non-ferrous substances. This is crucial in industries such as mining, recycling, and food processing, where the separation of magnetic and non-magnetic materials is essential. Refrigerator Magnets:  The magnets used in refrigerator doors and magnetic whiteboards are often made from hard ferrites. These magnets provide a cost-effective solution for everyday applications where a permanent magnet is needed. Automotive Applications:  Hard ferrites are used in various automotive applications, including in electric motors, sensors, and actuators. Their durability and resistance to demagnetisation make them suitable for these demanding environments. Permanent Magnet Motors:  Hard ferrites are utilised in the manufacturing of permanent magnet motors used in a range of devices, from small appliances to industrial machinery. These motors benefit from the reliable and long-lasting magnetisation provided by hard ferrites. Soft Ferrites On the other hand, soft ferrites possess low coercivity and remanence, allowing them to be easily magnetised and demagnetised. Soft ferrites are primarily used in applications where magnetic flux needs to alternate rapidly, such as in transformers and inductors. The composition of soft ferrites often involves mixtures of iron oxide and other metal oxides, such as manganese, zinc, or nickel. Unlike hard ferrites, soft ferrites are designed to exhibit minimal hysteresis loss and dissipate less energy in the form of heat during the magnetisation and demagnetisation cycles, making them suitable for applications requiring efficient magnetic coupling. Soft Ferrite Applications Transformers:  Soft ferrites are extensively used in the cores of transformers. The ability of soft ferrites to quickly switch magnetic states with minimal energy loss makes them ideal for transformers, where the magnetic field needs to alternate rapidly to induce voltage changes. Inductors:  Inductors, which store energy in a magnetic field, often use soft ferrite cores. Soft ferrites help reduce energy losses and heat generation in inductors, making them suitable for applications like power supplies, filters, and chokes. RFID Antennas:  Soft ferrites are employed in the manufacturing of antennas for Radio Frequency Identification (RFID) devices. The rapid response of soft ferrites to changing magnetic fields is advantageous in RFID applications where efficient communication between the tag and the reader is crucial. Magnetic Sensors:  Soft ferrites find applications in magnetic sensors, such as those used in automotive applications for speed sensing, position sensing, and anti-lock braking systems (ABS). The quick response and low hysteresis loss (energy lost as heat) of soft ferrites contribute to the precision of these sensors. Noise Suppression Devices:  Soft ferrites are used in noise suppression components, such as ferrite beads and chokes, to suppress electromagnetic interference (EMI) in electronic circuits. Placing soft ferrite beads on cables can help absorb and decrease high-frequency noise, enhancing the overall performance of electronic devices. Ferrite - A Versatile Material Since its discovery in 1930, ferrite has evolved into a key material in the world of electronics. In this blog we have explored what ferrite is and how it can be categorised into two different types – hard and soft. It is important to distinguish these two types of ferrites as they have unique properties which allow them to excel in particular applications. The key is in remembering that hard ferrites have a high resistance to demagnetisation, whilst soft ferrites can easily be magnetised and demagnetised. In the next part of our ‘Ferrite for Beginners’ series, we are going to be looking at some of the key terms that you should understand when referring to the properties of ferrite. Next in the 'Ferrite for Beginners' series: Understanding Key Terms Want to buy ferrite? Visit our shop now and see what we have in stock! https://www.shop.gatewaycando.com/magnetic

Electricity plays a fundamental role in our daily lives, allowing us to charge smartphones or power industrial machinery. With so many devices reliant on electricity it is important that they can manage this power efficiently, but what makes this possible? One solution that we are going to look at is ferrite. In this blog series ‘Ferrite for Beginners’ we will explore the world of ferrite – starting here by understanding why ferrite is used in the first place. Linear vs Switching Power Supplies To understand why ferrite is used within electronics, it can be useful to start by looking at power supplies, which help to bring electronic devices or circuits to life by providing them with the right type and amount of power. The two that we will be discussing are ‘linear power supplies’ and ‘switching power supplies’ (also known as switch mode power supplies). These are both types of regulated power supplies, which allow the output voltage of a circuit to be kept at a stable level. Linear Power Supplies A linear power supply takes in an AC (Alternating Current) voltage, from a source such as a wall outlet, and uses a transformer to reduce the voltage. It then uses a series of capacitors, diodes, and a regulator to convert this high voltage AC into a lower voltage DC (Direct Current) output. Image: Build Electronic Circuits Advantages Simplicity:  Linear power supplies have a simpler design, making them easier to understand and troubleshoot. Less EMI (Electromagnetic Interference): They generally produce less electrical noise, making them suitable for applications where interference can be a concern, like in audio equipment. Stable Output:  Linear power supplies provide a stable and continuous output voltage, which is beneficial for devices that require a consistent and reliable power source. Disadvantages Lower Efficiency:  Linear power supplies are less efficient compared to switching power supplies. They can waste more energy as heat, especially when converting high voltages to lower ones. Bulkier and Heavier:  Due to the use of transformers for voltage reduction, linear power supplies tend to be bulkier and heavier than switching power supplies. Limited Voltage Range:  Linear power supplies are less suitable for applications requiring a significant reduction in voltage, as they become less efficient and more wasteful when stepping down high voltages. Switching Power Supplies Switching power supplies also begin with an AC current which is converted into DC. Whereas linear power supplies use a transformer to reduce voltage, switching power supplies use a high-frequency switching technique. This rapidly switches the DC on and off using electronic switches (typically transistors), generating a high-frequency signal which is then fed into a transformer. These transformers can be much smaller in size compared to those in a linear power supply due to the higher frequency. Once the DC has passed through the transformer, it is smoothed out using capacitors and inductors to remove the high frequency and produce a stable DC output. The output voltage is then continuously monitored and adjusted to maintain a constant output even if there are variations in the input voltage. Advantages High Efficiency:  Switching power supplies are generally more efficient than linear power supplies. They waste less energy as heat during the voltage conversion process, making them more energy efficient. Compact and Lightweight:  Due to their design without bulky transformers, switching power supplies are smaller and lighter than linear power supplies. This makes them ideal for applications where space and weight are critical factors. Versatile Voltage Regulation:  Switching power supplies can efficiently adjust voltages up or down, making them versatile for various applications with different voltage requirements. Disadvantages Complex Design:  Switching power supplies have a more complex design involving semiconductors and high-frequency components. This complexity can make them more challenging to design and troubleshoot. EMI:  Switching power supplies can introduce high-frequency switching noise into the system, potentially causing electromagnetic interference. This may require additional filtering and shielding measures. Higher Cost:  The components and technology used in switching power supplies can make them more expensive to manufacture compared to linear power supplies. Ferrite Core Transformers Now that you can see the difference between linear and switching power supplies, we can look at where ferrite fits into the equation. Ferrite is commonly used within switching power supplies for the transformer that reduces the voltage. Ferrite works well at high frequencies and has properties that allow power supplies to operate efficiently whilst maintaining a compact design. Here’s how a ferrite core transformer works: Image: Build Electronic Circuits Ferrite Core The heart of the transformer is the ferrite core, these are available in different shapes such as “E” cores or “POT” cores and can be purchased in different sizes and materials. Primary and Secondary Windings Around the ferrite core, there are two sets of wires called “windings.” The first set is called the “primary winding” – this is where the electricity from the power source flows through. The second set is called the “secondary winding.” This is where the transformed electricity comes out, ready to power your device. Along with being used for transformers, ferrite is also commonly used in inductors and for minimising EMI. Let’s start by looking at inductors. Introducing Inductors Inductors are electrical components designed to store energy in a magnetic field. When an electric current flows through the coil of wire in an inductor, it creates a magnetic field around the coil. A key function of inductors is to resist changes in the flow of an electric current, and this resistance is created due to the energy stored in the magnetic field. Inductors have several important applications, including: Energy Storage:  Inductors store energy in their magnetic fields, and this stored energy can be released back into the circuit when needed. Smoothing Signals:  Inductors can help smooth out variations in electrical signals, acting like a filter to stabilise the flow of current. Filtering:  Inductors can be used as a filter to allow some frequencies to pass through a circuit whilst blocking other frequencies. Transformers:  Inductors can be used in transformers to help transfer electrical energy between circuits by creating a changing magnetic field. Whilst there are a few different kinds of inductors, we are going to be looking specifically at two – air core inductors and ferrite core inductors. Air Core Inductors An air core inductor is a device that stores electrical energy using coils of wire – they are called ‘air’ cores because there is no solid material at the centre of the coil, unlike some other types of inductors. They rely on the surrounding air to generate the magnetic field when an electric current flows through the coil. Let’s look at some features of air core inductors: Size:  They tend to be larger in size compared to inductors with magnetic cores. This is because air doesn’t concentrate the magnetic field as effectively as magnetic materials. Interference:  Air core inductors produce less magnetic interference, making them suitable for applications where minimising interference is important, such as in high-frequency circuits or radio-frequency devices. Applications:  Commonly found in applications where size is less critical, and maintaining signal clarity is more important. For example, they might be used in radio antennas. Ferrite Core Inductors A ferrite core inductor, on the other hand, uses a coil of wire wound around a core made of ferrite. The reason for using a ferrite core in an inductor is to enhance its performance – it does this by increasing the inductor’s ability to store energy in the magnetic field. Here are a few reasons why using ferrite is beneficial: Increased Inductance:  The presence of a ferrite core in an inductor increases its inductance. Inductance is a measure of how much energy the inductor can store. So, by using a ferrite core, we can have a more efficient and powerful inductor. Higher Efficiency:  Ferrite cores help in reducing energy losses. When an electric current flows through the wire in the inductor, some energy is lost as heat. Ferrite cores help to minimise these losses, making the inductor more efficient. Frequency Stability:  Ferrite cores are particularly useful at high frequencies. They can maintain their performance better than some other materials, making them suitable for applications like radio frequency (RF) circuits. Size and Weight Reduction:  Ferrite core inductors can often be more compact and lighter than their counterparts without ferrite cores. This is especially important in electronic devices where space and weight are critical factors. So, in summary, the ferrite core in an inductor improves its ability to store energy, increases efficiency, and can be more suitable for certain applications, especially those involving higher frequencies. Electromagnetic Interference (EMI) As mentioned above, we have introduced the concept of Electromagnetic Interference (EMI) which occurs when electronic devices or electrical systems create “noise” or disturbances in the electromagnetic field, affecting the normal operation of other nearby devices. We can break it down like this: Electromagnetic:  This refers to anything related to electricity and magnetism, which are two fundamental forces in nature. Interference:  Imagine you’re trying to listen to your favourite radio station, but there’s a lot of static or noise that makes it hard to hear the music clearly. That interference could be caused by various things, including other electronic devices nearby. Minimising EMI is crucial to ensure that different devices can work together without causing disruptions. Ferrite has a unique ability to absorb high-frequency EMI, meaning that it can reduce the amount of noise produced and in turn minimise the interference on other devices or systems. This is all well and good, but how do we use ferrite to manage EMI? Let’s look at some common ferrite solutions for reducing EMI. Ferrite Beads Ferrite beads are small cylindrical components with a hole in the centre. Placed around cables, they act as filters for high-frequency signals by introducing impedance (opposition to electrical flow), reducing EMI. They are commonly used on power cords and data cables in electronic devices to prevent unwanted signals from causing interference. Ferrite Cores Ferrite cores come in various shapes and are versatile components used in inductors, transformers, and cables to enhance inductance. By concentrating and guiding magnetic fields, ferrite cores contribute to efficient energy storage and transfer, leading to a reduction in EMI. Widely used in power supplies, audio equipment, and cables, ferrite cores play a key role in maintaining the integrity of electronic signals and preventing interference. Ferrite Sleeves (Cable Cores) Ferrite sleeves, also known as cable cores, are cylindrical devices designed to slide over cables. By absorbing and reducing unwanted noise, ferrite sleeves help to ensure that signals stay contained within the cables, preventing interference with other electronic equipment. Ferrite sleeves are commonly used on power cords, USB cables, and communication cables. Ferrite Plates and Sheets Ferrite plates and sheets are used in electronic devices or enclosures to address interference issues. Positioned on the surfaces of electronic devices or enclosures, they serve as barriers against electromagnetic radiation. This allows them to absorb or reflect radiation, reducing the likelihood of interference. Ferrite plates and sheets are frequently used in electronic devices and industrial equipment, contributing to effective EMI shielding and ensuring proper operation. Ferrite Snap-On Cores Ferrite snap-on cores (also referred to as clamp-on cores, clip-on cores, and ferrite clamps) are split cores that are easily snapped onto cables, without the need to disconnect them. They introduce impedance to high-frequency signals, reducing EMI without requiring major modifications to cables. Snap-on cores are used for EMI suppression on existing cable installations in computer systems, audio equipment, and electronic devices. Ferrite Chip Beads Ferrite chip beads are small, surface mount components used on printed circuit boards (PCBs). Acting as low-pass filters, they allow DC and low-frequency signals while reducing high-frequency noise. Ferrite chip beads are commonly used on PCBs in electronic devices like smartphones and computers for EMI suppression. Ferrite Balun Cores Ferrite balun cores are used in balun transformers for impedance matching and EMI suppression in RF circuits. These cores help convert between balanced and unbalanced (hence the name “balun”) signals while reducing common-mode noise (electrical interference that affects both the signal and ground conductors simultaneously). Ferrite balun cores are widely used in RF applications, antennas, and communication systems where impedance matching and EMI suppression are crucial. Why We Need Ferrite Efficient management of power is essential when it comes to electronics. As we have discovered, electronic circuits can produce electromagnetic interference (EMI) which may cause disruption to other nearby devices and systems. Ferrite not only helps to reduce this EMI, but also offers a way of managing power efficiently through the use of inductors. We hope that this first blog in our series has given you an insight into why there is a need for ferrite – next we will be looking more in depth at ferrite as a material itself, exploring its origins and the different types available. Next in the 'Ferrite for Beginners' series: What is Ferrite?

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