Magnetic Sensor Sensitivity units mV/V/gauss, etc.

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Discussion Overview

The discussion revolves around understanding the sensitivity of magnetic sensors, specifically how it is expressed in units of mV/V/gauss. Participants explore the implications of these units for sensing small changes in magnetic fields, with a focus on practical applications and the interpretation of datasheet specifications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant seeks clarification on the meaning of sensitivity expressed in mV/V/gauss and how to calculate the required sensitivity for detecting small changes in a magnetic field.
  • Another participant explains that sensitivity relates output voltage changes to input voltage and the magnetic field measured, suggesting that manufacturers provide literature for further guidance.
  • A participant references a specific datasheet, questioning whether a sensitivity of 1.0 mV/V/gauss indicates a 1 mV output change for every 1 gauss change in the magnetic field.
  • Further clarification is provided regarding the need to consider input voltage when calculating the effective sensitivity, with an example calculation given based on a typical input voltage.
  • One participant expresses uncertainty about interpreting datasheet specifications for sensitivity, linearity, and repeatability in the context of their application.
  • A participant mentions reaching out to manufacturers for product recommendations, indicating that the application is for a device rather than a laboratory project.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the interpretation of sensitivity and its implications for their specific applications. There are multiple viewpoints regarding how to approach the information presented in datasheets and the importance of various specifications.

Contextual Notes

Participants express varying levels of expertise, with some indicating a lack of familiarity with systems design, which may affect their interpretations of technical specifications. The discussion includes assumptions about stability of input voltage and the relevance of different specifications in practical applications.

Who May Find This Useful

This discussion may be useful for individuals involved in selecting magnetic sensors for practical applications, particularly those who need to understand sensitivity, linearity, and repeatability from datasheets.

VinnyCee
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So I've been looking at magnetic sensor datasheets and I see the sensitivity is usually listed in units of mV/V/gauss. What does this mean?

Let's say I need to sense changes in a magnetic field that usually ranges from about 10 gauss ( 1 mT ) to about 130 gauss ( 13 mT ). And I need to be able to sense 0.12 gauss ( 12 μT ) differnces in the field ( basically the range divided into 1000 equal parts ).

How would I calculate the sensitivity range that would be sufficient for such an application?
 
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Such a sensor has input voltage and output voltage. Hence you get how the output voltage changes per input voltage per the field measured. Assuming your input voltage is very stable, or you can account for its fluctuations in some other way, this then becomes output voltage per field. Any major manufacturer of such device should have some literature that will explain this in more details and offer some design guidance.
 
voko said:
this then becomes output voltage per field. Any major manufacturer of such device should have some literature that will explain this in more details and offer some design guidance.

So let's say for the http://www51.honeywell.com/aero/common/documents/myaerospacecatalog-documents/Missiles-Munitions/HMC_1001-1002-1021-1022_Data_Sheet.pdf, which has a sensitivity of 1.0 mV/V/gauss, this would mean that for every 1 gauss change in detected magnetic field, there would be a 1 mV change in output?

I notice there is lots of other information there, seems a bit overwhelming at first! I am most concerned with sensitivity, linearity and repeatability. All of these are described in the datasheet, but I'm not sure how to correlate what I need (described above) into what it would say on a datasheet for a suitable product. Any advice?
 
VinnyCee said:
So let's say for the http://www51.honeywell.com/aero/common/documents/myaerospacecatalog-documents/Missiles-Munitions/HMC_1001-1002-1021-1022_Data_Sheet.pdf, which has a sensitivity of 1.0 mV/V/gauss, this would mean that for every 1 gauss change in detected magnetic field, there would be a 1 mV change in output?

You need to factor in the input voltage. On that same datasheet, it is specified as a range from +2V to +12V, with the typical being +5V. With that voltage stable, the sensitivity will be 1.0 mV/V/Gauss x 5V = 5.0 mv/Gauss.

Any advice?

I am not an EE guy, so even if I give you advice in this area, don't listen to me. I just (I hope) I know the underlying physics, but when it comes to systems design I would be completely clueless. If what you do is for some laboratory project, you probably could get a digital magnetometer from them, such as this one http://www51.honeywell.com/aero/common/documents/myaerospacecatalog-documents/Missiles-Munitions/HMR2300.pdf and spare yourself a lot of trouble.
 
I sent an email to a few manufacturers to inquire about what products they may have which would be applicable here. Hopefully they'll get back to me soon with some good news!

It's not for a lab project, I'm trying to use it to make a device.

Using the info in the OP, can anyone tell me what I should be looking for in the fields "sensitivity", "linearity", and "repeatability" fields in a prospective device's datasheet?
 

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