I'm thinking about building an unsophisticated bench instrument for measuring magnetic field density, just to support my learning about electromagnetism and building magnetics for power electronics applications.
I'm thinking I'll want something that can measure up to about 1 tesla (T) and was generally thinking that using a linear Hall effect sensor of some description was the way to go.
There are a number of such projects out there on the web, but they all seem to have a substantially lower operating range, which I understand is perfectly useful for a variety of other applications.
The linear Hall effect sensor devices I've been able to find all seem to top out at much lower flux densities, like 600 gauss (G), which is 0.06 T.
So I'm wondering, are there any Hall effect sensors that can operate at the flux densities I'm designing for? Or is it perhaps silly to be looking for something in that range? I figured line transformer iron can operate at between 1 and 2 T before saturation, so I'd be in the right ballpark.
Best Answer
It seems most sensors on the market are made for very low to medium ranges up to 300mT, as you already observed.
Hall elements themselves usually allow field strengths in the order of a few Tesla, but the range is then limited by the electronics.
Some sensors allow to apply an offset voltage, which is applied to the signal before further processing. For example, I had students which tried to measure fields up to 1.2T in their setup consisting of 4 neodymium magnets and an iron yoke:
They used the "CASSY system", one of these ready-to-measure systems used at schools and universities for experiments. It had a probe with a hall element and was able to measure +/-1T (more precisely: -1.024...+1.023, you see it?). The system could be "calibrated" by defining the current reading as 0T. So, they put the sensor somewhere with -0.4T, "calibrated" it and were the able to measure more than 1T. The data looked fine, but we didn't check for linearity in that range.
So, it may be worth looking for pure hall elements without further electronics, which are a little difficult to find.
I found hallsensors.de which offer for example the CYAJ166A for fields up to 3T.
Another distributor is AKM.
However, these hall elements have a large part spread, so you have to calibrate your sensors. You can use a "reference magnet" which you measure with one of these 300mT sensors to get a precise value and calibrate your sensor against it.