Hall Effect Sensor Frequently Asked Questions

Magnetic field sensors either utilize an internal magnet or directly detect a permanent or electromagnetic field. The internal magnet sensors detect ferrous steel and produce either an analog or digital output. Hall Switches, Reed Switches, and other external magnet sensors detect the magnetic field from a magnet or electro coil. They also are available in analog and digital versions.

Magnetic fields decrease exponentially as the distance from the field decreases. Gear Detection Sensors typically require installation within 0.10″ of the target gear. Our most powerful Ferrous Metal Proximity Sensors can detect steel targets several inches from the sensor. For Hall Effect Switches and Analog Hall Effect sensors, the size, material, grade, and shape of the magnet will all affect the measurable gap range. More information is available in our Application Notes.

This is a confusing question, with conflicting answers listed across the Internet. The following methods will indicate the poles as defined within the magnetic sensing industry.

1. Use a compass: The south pole of a magnet will attract the end of the compass needle pointing north.
2. Float the magnet in still water, the north pole of the magnet will align with the magnetic north.
3. Opposites attract, use a magnet with known poles, the marked north will attract the south pole of the unknown magnet.
4. Purchase your magnets from Standex Detect, the south pole is labeled on the magnet or defined on the specifications sheet for potted magnets.

Chopper stabilization corrects the magnetic offset and allows our sensors to be made more sensitive. From the customer’s perspective, a chopper-stabilized sensor will trigger slightly after the magnetic field. This uncertainty will be from 0 to 1 / Chopper Frequency. Typically, this is less than 16uS. To learn more, we offer the following Application Note.

True 0 Speed means if you start today and one target passes the sensor in the next year, the sensor produces an appropriate pulse. Very Low Speed means the targets can pass by at less than 1 target per second, and the sensor works. Some competitors claim 0 speed on their Very Low-Speed Sensors even though they don’t work to true 0 speed.

There are 2 ways to measure speed from the continuous pulses produced from gear teeth:

1. Count the number of sensor pulses in a fixed period of time. If you count the number of pulses, make sure you are counting at least 20 pulses at your maximum speed.
2. Count the time between each sensor pulse. If you are measuring the time between pulses, make sure to use the same edge (rising or falling), and note that the chopper-stabilized sensors will have a tooth-to-tooth uncertainty of up to 1 / the chopper frequency. Typically, this is 16uS.

Never try to measure the time from rising edge to falling edge for speed.

We offer fully programmed tachometers to pair with our sensors. Contact us with your requirements.

Every sensor needs something to ‘detect’. Hall Switches and Analog Hall Sensors detect magnets. Ferrous Metal Proximity Sensors detect ferrous steel. Gear tooth sensors detect gear teeth, holes, or other ferrous targets. If you start by selecting Sensors By Function you can first determine what the goal of the sensor is and then you will be provided a list of target options to choose from.

Yes. We have multiple ‘application specific’ sensors that are not listed. We can also provide different cable lengths and connection options on request. Contact Engineering to see if we can make a sensor for your application.

Standex Detect OEM manufactures magnetic field sensors specific to the requirements of applications for many of our customers.  Whether you require standard functionality but need the sensors branded with your part number, or you require a fully custom sensing solution, Contact Engineering to discuss how we can be best meet your custom needs.

A quadrature sensor can give you direct information and can increase the measuring system’s resolution to 4 times the number of targets. It produces 2 square wave outputs, Ch A and Ch B. So, you get 4 ‘edges’ from each tooth or target: Ch A rising and falling, Ch B rising and falling. In one direction of movement, A leads B. In the other direction, B leads A. If a system has a tooth-to-tooth spacing of .100″, each ‘edge’ is approximately .025″ apart. To learn more, we offer the following Application Note.

A quadrature gear tooth sensor has 4 edges, Ch A rising, Ch B rising, Ch A falling and Ch B falling. Gear tooth sensors never have exactly 50.0% duty cycle signals, and the phase angle is never exactly 90.0 degrees. Therefore, the time between these 4 edges is not exactly the same.

To measure speed, look time between the same edges; for example, Ch A falling to the next Ch A falling. Note the non-chopper stabilized sensors have less tooth-to-tooth ‘chatter’ caused by the chopper frequency.

One option is to mount magnets directly to your shaft. Another option is a shaft collar containing magnets that can be attached to the shaft. These targets can then be paired with a Hall Effect sensor to give you the outputs you need. We provide a variety of target options and can also create custom solutions as required by customers.

You can detect a steel bolt head or a hole in a steel target with a gear tooth sensor or a ferrous metal detection sensor. Otherwise, you can attach a magnet to the rotating target and detect it with a Hall Switch. We provide raw magnets, magnets potted into threaded bolts, and magnets mounted on shaft collars. Our Sensors By Target guide breaks down all of our product lines by target.

There are several differences. The Single Channel DS is true 0 speed, chopper-stabilized, requires the direction of rotation orientation, and looks for target left vs. target right. The Target Tracker DSO works at very slow speeds, does not have chopper noise, and does not require orientation. It is sensitive to metal close and metal far.

It depends on your requirements. In general, use the DS Gear Tooth Sensor if you have a standard gear, and a Target Tracker DSO if you can’t orient the sensor to the gear or want to produce pulses that track the teeth pattern. The DS sensor behaves more consistently from part to part, but if you gap them close enough the DSO sensors work great.

If the gear you are sensing has teeth that are longer than .250″ at the outside diameter, or the teeth are farther apart than .650″ at the outside diameter, use the Target Tracker DSO.

Standex Detect is setup for programming Melexis MLX90215, MLX90251, and MLX90316 sensors. Whether you require a few for prototyping/testing or you need small to large volumes for production, contact us to discuss your specific needs. Standex Detect is also capable of programming other sensors not listed above. Contact us to discuss any programming needs.

Standex Detect is setup for programming Micronas HAL805 and HAL1000 sensors. Whether you require a few for prototyping/testing or you need small to large volumes for production, contact us to discuss your specific needs. Standex Detect is also capable of programming other sensors not listed above. Contact us to discuss any programming needs.

Yes, we have built custom magnetic sensors that have traveled down the core of a Nuclear Reactor.

We have designed exact replacements and can also provide sensors with the same outputs and thread types. Check our Cross-Reference page to see if we list a replacement, if not contact Engineering to discuss the options.

Lots of times we can provide a direct replacement. Check our Cross Reference or contact us.

Yes. By starting with our standard products, you can find all of our target magnet options, mating connection options, meters and controllers, and other sensor accessories.

Standex Detect is certified to the ISO 9001:2015 quality standard.

Although CE marking is not standard, a majority of our hall effect sensors can be CE marked for a nominal charge. Contact sales for details.

Contact our Engineering Department to discuss CE certification. We are working on adding ‘CE’ options to our standard product selection.

We do offer RoHS compliant products. Some products may not be RoHS compliant, unless specifically requested on the purchase order or otherwise acknowledged in writing. It is up to the customer to determine which if any exemptions apply to the end-line device that uses our products. Standex Detect only warrants that product sold as RoHS compliant meet this certification and assumes no liability for misuse or misrepresentation of non-compliant product.

Lead is the only item of concern. Lead-free soldering is more expensive and not as reliable as conventional soldering. We offer RoHS sensors on a custom basis. If you require RoHS compliant Hall Effect sensors, contact us with your requirements.

We have quite a few application notes but have not had a chance to add them all to our website. Check out our published Application Notes or contact engineering if you cannot find the information you require.

Send a request through our Contact Page. Make sure to fill in the proper e-mail address for the reply.