Overview of Selecting the Appropriate Hall Effect Sensor and Target Magnet:
Charts in this application note indicate the typical gap ranges that our Hall Effect Switches will detect target magnets available on our website. All curves and switch points are based on the sensing element location in a typical housing and the calculated magnetic field strengths.
Using the Charts:
Each chart shows the typical output curve of the field produced by the South Pole of multiple magnets at room temperature. The upper horizontal line indicates the worst case for the sensor type to switch (max switch point or highest possible field required). The middle line indicates the typical switch point for the sensor. The lowest line indicates the smallest possible field that could potentially trigger the sensor (min switch point).
Sensors are 100% tested to switch at the max switch point, but most will operate closer to the typical switch point. The guaranteed range* that a given sensor will detect a specific magnet will be from a gap of 0.000” to the point where the curve reaches the max switch point. The minimum gap required to ensure that the sensor will not trigger the magnet is the below where the curve crosses the min switch point.
Below each chart is a table indicating the max, typical, and min switch point for the sensor and each magnet type listed. Click on the magnet part number to open the product page for the specified magnet.
*Magnetic fields will be affected by the presence of steel or other magnets. Standex Detect recommends testing any given magnet and sensor combination in the application to determine installation gaps. Non standard housings may also position the sensing element closer to or farther from the magnet surface.
Measuring Air Gap
The figure below shows how the air gap is measured between a sensor and target magnet for the charts and data in this Application note.
Charts
Each chart lists common Neodymium Cylinder Magnets available from Standex Detect. Data for other magnets is available upon request.
Click the link below to go direct to the page listing the sensitivity of the sensor and max gap data for each characteristic.
HS / HSQ / HSCD / DHS / DHSS
The HS element used in the above sensors switches between 85-157 Gauss, with a typical switch point of 120 Gauss.
