02/10/2019: Making the Mag Field with Permanent Magnets

A project log for Making Sense of the Hall Sense

The Physics Behind The Hall Effect Sensor

TheRealDubzTheRealDubz 02/11/2019 at 01:080 Comments

To generate a steady B-field for our experiment, we have two options to choose from:

  1. Permanent Magnets
  2. Electromagnets

Before I choose a path, I'd like to do a quick study to determine the cost of building a magnet with a 1 Tesla flux density through a 1" x 1" area.  If more than 1 Tesla is needed, we can approximate the cost as a linear function of flux density.

Using Permanent Magnets:

Benefits of using permanent magnets are:

  1. Different sizes, shapes, and strengths readily available
  2. Stacking smaller magnets is equivalent to a single magnet of the same thickness
    1. Flux density (B) dependent on the magnet's dimension in the direction of the magnetic field's axis
  3. Setup would require a simple mounting fixture

Some cons:

  1. If using multiple small magnets, the B-field will not be uniform in certain places (compared to a larger permanent magnet or electromagnet) due to the gaps between the magnets.  (Not a show stopper)
  2. Can get expensive as the number of magnets needed is increased to increase the B-field.

Example Jig set up:

Analysis using an electromagnet coming in the next log...