I want to make use of an alegro A1324LUA-T hall sensor to sense a very small magnetic field change would it be possible?

[assasinchop7]

Hi I am looking into using an Alegro A1324LUA-T for sensing very small magnetic field changes. The data sheet shows that the sensor gives a 5mV/G change in voltage so I can sense a 0.1 Gauss change if I can capture voltage change of 0.5 mV. Does anyone have any experience measuring such a small change in voltage on a rather large output signal as the sensor outputs 2.5 V when no field is present. I am wondering if there is any way that can pick up 0.1 mv change with a good accuracy using arduino.

[johnerrington]

@assasinchop7

Alegro A1324LUA-T

Hi there. As its your first post please read this

How to get the best out of this forum

Welcome to the Arduino forum! A guide explaining how to get the best out of this forum is available at the link below. Please read it:

its polite to provide links to hardware so we know what you are talking about.

a1324-5-6-datasheet.pdf

@assasinchop7

Does anyone have any experience measuring such a small change in voltage on a rather large output signal as the sensor outputs 2.5 V when no field is present.

Yes that isnt a problem ; you can use an op amp to remove the 2.5V offset as explained here

Using Operational Amplifiers in your Arduino project

8: Example 2. Amplifying a signal from a sensor when it has an offset voltage Many common sensors will produce a voltage that does not "sit" on the 0V rail, as shown in the blue line in this example. [opamp signals3.png] The green signal is too small (say 0.04V) to measure with any accuracy; however by amplifying it by 100 we get a signal of around 0.04*100 = 4V that can be measured. However the signal on the blue line is small, but has a dc offset of about 2.5V; multipling that by 100 gives…

[hammy]

I would have a good read of the data sheet .
You are well down into the noise / drift area of its characteristic so it may not detect that very well .
Google measuring small magnetic fields ,

Some details of the project may reveal better solutions

[assasinchop7]

Hi John,

Thank you for your inputs. I have some questions regarding your post. I am new to op amps and electronics in general so bear with me.
Could you let me know which op amp you used for your project?
In your circuit diagram it shows two sensors, did your project make use of two sensors and if so how would a circuit look like for a single sensor?
In my project I want to bias the hall sensor with a permanent magnet and want to sense the difference in magnetic field when a material is placed between the magnet and the hall sensor would I be able to null out the hall voltage when it is biased using a permanent magnet?
The material is slightly permeable hence the small magnetic field change sensing requirement.

Again thank you for the inputs.

[johnerrington]

I used a hall effect sensor A1302 for my own experiment, to look for small changes in magnetic field. It gives a bidirectional voltage output biased to Vcc/2.
...The sensor is shown in the diagram below as a pair of thermistors (you could use those, or light dependent resistors)

Sorry if that isnt clear. The output from the single sensor is V1 in the diagram

@assasinchop7

Could you let me know which op amp you used for your project?

Recommendations
For a single supply driven from your Arduino's 5V or 3.3V supply,
the MPC6002 is usually a good choice; if you need a faster response use the MPC6022.

The easiest way to find out what will work is by experimentation. For your application I'd suggest STARTING with values of R1 = 1k and R2 = 10k, and look at your results to see what the sensitivity and range feel like in yoiur practical situation.