How are Reed Relays Constructed?

Reed relays have become an essential component in a wide range of electronic devices and systems. Their ability to switch high voltages, and currents, and operate effectively in harsh environments makes them a popular choice in various applications. But how exactly are reed relays constructed? In this article, we'll explore the intricate details of reed relay construction, from the materials used to the manufacturing process and the final product.

The Basics of Reed Relays

Reed relays consist of two metal reed contacts that are hermetically sealed inside a glass tube filled with an inert gas. When a magnetic field is applied to the relay coil, the reed contacts move together or apart, completing or interrupting the electrical circuit. This simple yet effective design makes reed relays suitable for both low-level and high-level signal switching. Let's delve into the construction process and understand the key components of reed relays.

The Reed Switch

The heart of a reed relay is the reed switch, which is made up of two thin, magnetic, metal alloy reeds sealed in a glass envelope. The reeds are often made of nickel-iron or other ferromagnetic materials, and the glass envelope is typically filled with a dry inert gas to prevent oxidation of the contacts. The outer leads of the reed switch are then connected to the relay coil, which provides the magnetic field necessary to open or close the contacts.

The process of creating the reed switch begins with selecting the appropriate metal alloy for the reeds. The chosen alloy should have the necessary magnetic properties to respond to the magnetic field of the relay coil. The reed switch is then assembled by aligning and welding the two reeds inside the glass envelope, ensuring that they are perfectly aligned and can move freely without sticking. Once the reed switch is sealed, it undergoes rigorous testing to ensure proper operation and reliability.

The Relay Coil

The relay coil is responsible for generating the magnetic field that actuates the reed switch. Typically made of copper wire wound around a bobbin or form, the relay coil is a crucial component in the construction of reed relays. The number of turns in the coil and the gauge of the wire are carefully chosen to produce the appropriate magnetic field strength required to operate the reed switch.

During the manufacturing process, the copper wire is wound around the bobbin or form to create the relay coil. The ends of the wire are then connected to the external leads of the reed switch. The entire assembly is then enclosed in a protective housing, ensuring that the coil and reed switch are securely held in place. Once assembled, the relay coil undergoes stringent testing to verify its magnetic field strength and overall reliability.

Contact Material and Sealing

The materials used for the reed contact blades play a significant role in the performance and reliability of reed relays. These contact blades are typically made of a high-quality, highly conductive material such as rhodium, ruthenium, or tungsten. The choice of material is crucial as it directly impacts the switch's ability to carry high currents and its resistance to contact welding and erosion.

After selecting the appropriate contact material, the contact blades are carefully shaped and formed to ensure proper contact alignment and stability. The contact blades are then sealed inside the glass envelope, along with the reed switch, to maintain a hermetically sealed environment. This sealing process is critical in preventing any outside contaminants from affecting the contact material and compromising the relay's performance.

Final Assembly and Testing

Once all the individual components are assembled, the reed relay undergoes a series of tests to ensure that it meets the required specifications for proper operation. These tests include checking contact resistance, contact release time, insulation resistance, and contact carry current. Any deviations from the specified values are carefully analyzed, and the relay may undergo adjustments or repairs to meet the necessary criteria.

After passing the rigorous testing phase, the reed relays are carefully packaged to protect them from physical damage and environmental factors during transportation and storage. The final products are then ready to be integrated into various electronic applications, ranging from telecommunications to industrial control systems.

In conclusion, reed relays are constructed with meticulous attention to detail, ensuring that each component meets the stringent requirements for performance and reliability. From the reed switch to the relay coil and contact materials, every aspect of the construction process contributes to the overall functionality of reed relays. With their ability to handle high voltages, currents, and harsh environments, reed relays continue to be an indispensable component in the world of electronics.