Carrier Hall Effect Sensor: A Comprehensive Guide

The carrier hall effect sensor is a versatile and widely used position sensor that can measure the magnitude and direction of magnetic fields with high accuracy and precision. It operates on the principle of the Hall Effect, which is the production of a voltage difference (Hall voltage) across an electrical conductor when a magnetic field is applied perpendicular to the current flowing through the conductor.

Technical Specifications of Carrier Hall Effect Sensors

Carrier hall effect sensors have several key specifications that can be used to evaluate their performance:

Sensitivity

The sensitivity of a carrier hall effect sensor is the change in output voltage per unit change in magnetic field strength. It is typically expressed in millivolts per Gauss (mV/G) or volts per Tesla (V/T). The sensitivity depends on factors such as the materials used in the sensor, the sensor’s geometry, and the bias current applied.

Linearity

Linearity is a measure of how closely the sensor’s output voltage changes in proportion to the magnetic field strength. It is usually expressed as a percentage of full scale or as a linearity error in volts. Linearity depends on the sensor’s sensitivity, the range of magnetic field strengths being measured, and the sensor’s temperature.

Resolution

The resolution of a carrier hall effect sensor is the smallest change in magnetic field strength that can be detected by the sensor. It is often expressed in terms of the minimum detectable magnetic field (MDMF) or the noise equivalent magnetic field (NEMF). Resolution depends on the sensor’s sensitivity, noise level, and signal-to-noise ratio (SNR).

Hysteresis

Hysteresis is the difference in output voltage between increasing and decreasing magnetic field strengths. It is usually expressed as a percentage of full scale or as a hysteresis error in volts. Hysteresis depends on the sensor’s materials, geometry, and magnetic history.

Temperature Coefficient

The temperature coefficient of a carrier hall effect sensor is the change in output voltage per degree Celsius of temperature change. It is typically expressed as a percentage of full scale per degree Celsius or as a temperature coefficient of sensitivity (TCS). The temperature coefficient depends on the sensor’s materials, geometry, and bias current.

Practical Considerations for Carrier Hall Effect Sensors

In addition to the technical specifications, there are several practical considerations that can affect the performance of carrier hall effect sensors in real-world applications:

1. Physical Size: The physical size of the sensor can be an important factor, especially in applications with limited space.
2. Power Consumption: The power consumption of the sensor can be a critical factor, particularly in battery-powered or low-power applications.
3. Sensitivity to External Magnetic Fields: Carrier hall effect sensors can be sensitive to external magnetic fields, which can affect their accuracy and precision.
4. Susceptibility to Interference: The sensor’s susceptibility to interference from other electrical devices can also be an important consideration.

Example: Allegro A1302 Carrier Hall Effect Sensor

The Allegro A1302 is a linear carrier hall effect sensor with the following technical specifications:

• Sensitivity: 1.5 mV/G
• Linearity Error: ±3%
• Resolution: 5 G
• Hysteresis: ±1%
• Temperature Coefficient of Sensitivity: ±0.5%/°C
• Physical Size: 4.0 mm x 2.5 mm x 1.2 mm
• Power Consumption: 15 mW
• Magnetic Field Range: ±20 G
• Operating Temperature Range: -40°C to +125°C
• Built-in Overcurrent Protection

DIY Project: Building a Simple Carrier Hall Effect Sensor Circuit

To build a simple carrier hall effect sensor circuit, you will need the following components:

• A carrier hall effect sensor (e.g., Allegro A1302)
• A voltage regulator (e.g., LM7805)
• A capacitor (e.g., 10 μF)
• A resistor (e.g., 1 kΩ)
• A breadboard and jumper wires
• A magnetic field source (e.g., a magnet)

Follow these steps to build the circuit:

1. Connect the voltage regulator to the breadboard, making sure to connect the input pin to the positive voltage supply (e.g., 5 V), the ground pin to the negative voltage supply (e.g., GND), and the output pin to a power rail on the breadboard.
2. Connect the capacitor in parallel with the voltage regulator, with the positive leg connected to the output pin and the negative leg connected to the ground pin.
3. Connect the carrier hall effect sensor to the breadboard, making sure to connect the supply pin to the power rail, the ground pin to the negative voltage supply, and the output pin to a spare row on the breadboard.
4. Connect the resistor in series with the output pin of the carrier hall effect sensor, with one end connected to the output pin and the other end connected to a spare row on the breadboard.
5. Connect a jumper wire from the spare row where the resistor is connected to an analog input pin on a microcontroller or other data acquisition device.
6. Place a magnet near the carrier hall effect sensor, making sure to orient the magnet so that the magnetic field is perpendicular to the sensor’s sensitive axis.
7. Measure the voltage output of the carrier hall effect sensor using the microcontroller or data acquisition device, and observe how the voltage changes as the magnet is moved closer or further away from the sensor.

Congratulations! You have built a simple carrier hall effect sensor circuit that can detect the presence and strength of a magnetic field. You can use this circuit for a variety of projects, such as building a magnetic field sensor, a position sensor, or a speed sensor.

References:

1. Sensor Technology Handbook – OLLINTEC
2. Sensing and Sensor Fundamentals – ResearchGate
3. DEPARTMENT OF DEFENSE STANDARD PRACTICE – CADE