In order to use magnetic sensors, you must properly position and orient bar magnets near the sensor. In order to do this correctly, you must understand how a sensor responds to magnetics fields. By knowing the shape of a bar magnet's field, you can easily determine how to operate a sensor with a bar magnet.
Bipolar switches are similar to latches. They activate with one pole and then deactivate with the opposite pole. Unlike a latch, the response to south and north pole is probably not symmetric. A particular device might respond more to one pole than the other.
A Hall-effect latch is a device that is activated by one pole of a magnet and deactivated by the other. In many types of latches, the south pole activate the latch and the north pole deactivates. Once the latch has been activated or deactivated, it stays in the same electrical state until the other magnet pole is brought near.
A unipolar switch is a device that responds to a magnetic field. When the correct pole of a magnet is brought near, it turns on. When the magnet is moved away, it turns off. The actual details are more complicated, but this is the basic idea.
Simulating fields from bar magnets used for sensor applications is among the easiest electromagnetic simulation tasks. There are two main methods for doing this: finite-element analysis (FEA) software, and direct solutions of Maxwell's equations.
Proximity sensing provides an on/off response when a magnet approaches close enough to a digital magnetic sensor. This is useful for detecting things such as door closures, object presence, or home positioning. This article looks at the situation where the magnet moves parallel to the sensor. A numerical example will be worked through to illustrate the process of magnet design.
You have a magnetic sensing application. You have a tentative idea as to the magnet and sensor design you'd like to use. One of the most important things you can do is run a feasibility study. This will help you decide how much chance of success your design has before you start working on it.
Proximity sensing provides an on/off response when a magnet approaches close enough to a digital magnetic sensor. This is useful for detecting things such as door closures, object presence, or home positioning. This article looks at the situation where the magnet directly approaches the sensor.