Magnetic Reed Switches vs. Hall Effect Switches: Key Differences

Magnetic sensing technologies detect changes in magnetic fields to determine position, proximity, or motion. These include reed switches, Hall effect sensors, and even magnetoresistive sensors. They are vital in automation for non-contact position sensing, security systems for door/window status detection, and robotics for movement control.

In this blog, we’ll compare magnetic reed and Hall effect technologies to help you choose the right limit switch for your application.

Basic Working Principles

Here’s an overview of how each switch detects magnetic fields and converts them into electrical signals:

Reed Switch

A reed switch consists of two thin, ferromagnetic metal reeds enclosed in a glass tube filled with inert gas. When a magnetic field is brought near, the reeds become magnetized and attract each other, closing the circuit. As soon as the field is removed, the reeds separate, which opens the circuit. It acts as a simple, passive on/off switch triggered by proximity to a magnet.

Hall Effect Switch

A Hall effect switch is a solid-state device that generates a voltage when exposed to a magnetic field perpendicular to the semiconductor’s current flow. Internal electronics process this voltage to produce a digital or analog output. It also requires a constant power supply and can detect magnetic field presence, strength, and polarity.

Electrical and Mechanical Characteristics

Below are the key electrical and mechanical characteristics of reed and Hall effect switches:

Reed Switch

Magnetic reed switches possess the following characteristics that make them suitable for simple, low-power applications:

• Operates without external power: The switch functions passively and does not require a power supply.
• Uses mechanical moving contacts: It contains two ferromagnetic reeds that physically move to open or close the circuit when exposed to a magnetic field.
• Prone to contact bounce during switching: The mechanical action can cause the contacts to momentarily bounce, creating potentially unstable signals during fast switching applications.
• Enclosed in a fragile glass housing: The switch is sealed in a thin glass tube, which can easily break under mechanical stress or vibration.
  • MagneLink switches overcome this weakness by encasing the Reed switch component within a housing to increase the finished switch’s ruggedness to better perform in tough environments.
• Operates reliably in dirty or wet environments: The sealed MagneLink housing used on the finished Reed switch ensures resistance to dust, moisture, ice, and other environmental contaminants.

Switches at relatively slow speeds: Due to the movement of internal parts, the reed switch responds slower than solid-state alternatives when used in fast switching applications.

• Provides an easily monitored input signal: With a simple make-or-break operation, the reed switch provides a simple input signal for system monitoring of open or closed states.

Hall Effect Switch

The following characteristics of Hall effect switches make them highly suitable for applications requiring durability in harsh or complex environments:

• Detects magnetic field polarity: The Hall effect switch can sense the presence and polarity of a magnetic field, allowing for directional detection.
• Supports analog or digital output: Depending on the sensor type, it can provide a continuous analog signal or a binary digital output.
• Provides consistent performance over time: With no mechanical components, the switch maintains stable operation and accuracy over long periods.
• Operates reliably in dirty or wet environments: The sealed, solid-state design ensures resistance to dust, moisture, and other environmental contaminants.
• Integrates easily with microcontrollers: It interfaces directly with digital logic systems, making it suitable for embedded and automation applications.

Common Applications

Here are the common uses of reed switches and Hall effect switches across industries:

Reed Switch

Reed switches are commonly used in simple magnetic sensing tasks such as door and window sensors in security systems and float-level sensors in fluid tanks. They are also found in bicycles and treadmills for speed or position sensing due to their simplicity and low cost. In industrial systems, they serve as a simple, passive limit switch.

Hall Effect Switch

Hall effect switches are used in automotive systems for crankshaft and camshaft position sensing, gear speed sensors, and position detectors. In industrial automation, they serve as non-contact limit switches, encoder components, and proximity sensors. They are also common in consumer electronics, such as detecting laptop lids’ open/closed state or smart cover positioning in tablets.

Looking for a Reliable Limit Switch? MagneLink Has You Covered!

MagneLink offers both Reed and Hall effect switches that deliver high performance and durability across various applications. Whether you need a simple, passive solution or a more polarity sensitive sensor, we have the perfect magnetic switch for your needs.

Contact us today for custom solutions!

What is a Hall Effect Sensor?

Hall Effect sensors are used for detecting and measuring proximity, position, and speed, through their ability to sense magnetic fields. As non-contact sensors, they are useful for measuring AC and DC currents. This blog will explain the principles behind Hall effect sensors and their industrial applications.

What is a Hall Effect Sensor?

The Hall Effect, named after its discoverer Edwin Hall, refers to the generation of voltage in a current-carrying conductor, perpendicular to the direction of the current flow, when the conductor is immersed in a magnetic field. A Hall Effect sensor is a thin piece of a conductor with current flowing along its length and a voltage detector connected across its width.

When electric current traverses the sensor is in a magnetic field, the detector will register a small voltage. This voltage can be used to measure fluctuations in the magnetic field caused by changes in position, proximity, pressure, speed, temperature, or other factors.

Since Hall Effect sensors do not have any moving parts, they are more robust and durable than reed switches. However, they are also more expensive since they need a constant electrical current flowing through them.

Types of Hall Effect Sensors

Hall Effect sensors are broadly divided into two categories: analog and digital. The analog sensors produce a continuously varying voltage output while the digital version has just two output voltages: high or low.

Some of the sub-categories for Hall Effect switches include:

Vane-operated

These are digital proximity sensors that detect the presence or absence of a ferrous vane that passes through a gap between the two components of the vane-operated sensor: a permanent magnet and a Hall Effect sensor.

Digital current

This sensor also has two components in close proximity: a Hall Effect sensor and an electromagnet. The magnetic field produced by the electromagnet when current passes through its coils changes the output of the Hall Effect sensor.

Linear current

This is similar to the digital current sensor, except the output is analog.

Closed-loop current

Also called null balance current sensors, they work by nullifying the magnetic field being sensed by driving a current derived from the sensor output. Though they have excellent response, accuracy, and linearity characteristics, they are bulky and expensive due to the additional components required to generate the null balance current.

Gear tooth

As the name implies, these sensors detect the teeth of a gear as they pass by the sensor. Gear tooth sensors are similar to vane operated sensors but have additional circuitry to accurately measure speed. They are used in a variety of counting and speed sensing applications.

Applications for Hall Effect Sensors

As evident from the various categories of sensors mentioned above, Hall Effect sensors can be used for a wide range of applications, such as:

• Automated product handling
• CNC equipment
• Compactors / Balers
• Motion detectors
• Position sensors (ex: doors)
• Robotics (ex: limit switches)
• Safety interlocks (ex: defeat resistant safety switches)

Considerations for Hall Effect Sensor Design

The important factors that influence the design of a Hall Effect sensor include:

• Magnetic fields. The field produced by a magnet depends on its shape and size, the material used to construct it, the material in the path of the magnetic flux, and whether it is used as a unipolar or bipolar magnet.
• Electrical considerations. What is the maximum current the sensor will have to handle? Is there a constant voltagesupply available to supply the sensor? What is the maximum flux it will experience? Should the output be analog or digital?
• Operating environment. The temperature range over which the sensor must operate is an important environmental factor. Outdoor applications may require weatherproof housing for protection from rain and snow.
• As with all industrial components, cost is an important issue with Hall Effect sensors. The operating temperature range, packaging requirements, precision and sensitivity of the output, and other features required by the application determine the final cost of the Hall Effect sensor.

Hall Effect Sensors from MagneLink

MagneLink has over 25 years of experience designing high-quality custom magnetic switches and sensors. Get in touch with us for all your Hall Effect magnetic switch requirements.