working of a calibrated hall probe

extremcurious

i am not able to understand what IS exactly a hall probe and how it works. also how do we calibrate a hall probe??? anyone please help!!!!!!!

Vanadium 50

Is there something here that is unclear? http://en.wikipedia.org/wiki/Hall_effect

extremcurious

thanks! i understood it's working but again how do we calibrate it??

Vanadium 50

How do you think someone would calibrate it?

extremcurious

i don't know!!! and by the way u are making me feel EXTREMELY dumb.

Vanadium 50

I can't help how you feel. But I am trying to teach you how to find out things for yourself.

How would you calibrate a rule? How would you calibrate a thermometer?

And please, no text speak.

extremcurious

i am confused about why DO we need to calibrate a hall probe? i mean can't we just connect it to some device that measures the voltage across the hall probe, when it's placed in a magnetic field????

K^2

You can, but how would you determine how much voltage corresponds to how much magnetic field? While the theory is pretty straight forward, the actual reading will depend on any number of imperfections, amount of current you draw from the probe when measuring the voltage, and orientation of magnetic field. These are some of the reasons you need to calibrate it.

extremcurious

okay,so for every hall probe of different materials the voltage will be different, keeping all other factors same??

CWatters

Indeed.

Rolling off the factory line that makes them you have an assembly called a Hall effect probe. That contains a sensor (which might not allways produce exactly the same signal) and an amplifier to convert/scale that signal to a particular voltage range.

Ideally all the probes produced by the factory would work exactly the same and stay working exactly the same for ever. However that might not be the case due to component tollerances and/or components aging. I'm sure you are aware that even resistors never have exactly the value they are meant to. You can buy them with a specified tollerance (10%, 5%, 2% etc).

To solve this problem it would be reasonable to make some part of the Hall Probe adjustable and then check and adjust each one to ensure they all work the same before they are dispatched.

How would you go about doing that for a Hall effect sensor? What test equipment would you need?

extremcurious

i could take a coil that has current passing through it and find it's field strength by substituting in the formula B=NI/L and then place the probe in the coil and find out the voltage. and then do it again for different values of I. that's what i thought but is it right??

nsaspook

The best hall current probes are operated in the zero-flux mode. (closed loop) A secondary current winding is used to null the flux generated by the current conductor wire.

http://www.lyr-ing.com/DocumentosLyR...ransducers.pdf

Vanadium 50

That's one way. The problem you will run into is that it will be difficult to do this more accurately than a few percent. But you have the right idea - compare the measurement to a known field.

There are several ways to do this. One is to use a more sensitive probe, say an NMR probe. You calibrate the Hall probe so that it reproduces the result of the NMR.

extremcurious

Thanks a lot for your help! Sorry couldn't reply earlier and i know this is way to late but unforeseen problems arose. Thanks very much once again.