Designing Magnetometer

Discussion in 'The Projects Forum' started by earmenda, Dec 23, 2011.

  1. earmenda

    Thread Starter New Member

    Dec 22, 2011
    First Post. I will be designing a magnetometer over the next few weeks and was looking for some guidance.

    I plan on using a Arduino board to give it a few features. Power readings from electronics is one of the main features (which will be a rough estimate).

    Where to start with a sensor is where I am lost. I would like to use a hall sensor. I blindly ordered some and realized that was a mistake as I didnt really understand the data sheet. With magnetic fields I have no idea what range of values i should be looking for in a permanent magnet or the field emmited from a current. The sensor I ordered whenever a permanenet magnet approached it it instantly was saturated and have been lost since then. Would it also be necessary to have multiple sensors to account for different ranges?

    The way i see this is there will be four components. Voltage regulator, microcontroller, LCD display and the sensor.

    *Edit: LED display*
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
    First you need to know the strength of the magnetic field you want to measure. Then you choose an appropriate sensor. You need to know if it's static or alternating, if the latter at what frequency.

    Have a look HERE. Page 3 gives you an overview about measuring ranges of different measuring methods.
  3. earmenda

    Thread Starter New Member

    Dec 22, 2011
    Thanks for the reponse.

    Looks like what I really would like is a gaussmeter. The range would start at 1mT but what should I really expect from permanent magnets?

    Lets say i would like to handle both static and alternating forms. With a continous signal would I be able to process either in the microcontroller by sampling?
  4. earmenda

    Thread Starter New Member

    Dec 22, 2011
    One of the sensors I tried out was the HAL401SF-A,

    Hall Sensor.JPG

    I believe this is the photo i should look at while looking for a range, -100mT to 100mT is linear under Vdd = 4.5V.

    But when i tried this in a lab, the magnets i bought just automatically saturated it. I cannot find much information online on the field of permanent magnets sorry.
  5. steveb

    Senior Member

    Jul 3, 2008
    Modern day magnets are quite strong. For example a typical neodymium based magnet would have a field of many hundreds of mT near the surface. If you are just trying to test the system, you can (of course) move the magnet further away.

    I've used the Allegro A1302 devices before, which I believe has a +/- 200 mT range, if memory serves me.


    P.S. I got your PM about this thread you were starting, but I could not respond to you because you had the PM feature disabled. Welcome to AAC.