The Shop > Electronics & IC Programing
Measuring current using hall-effect sensor
PekkaNF:
Thank you. Very good and practical info. I have noticed the need for closely coupled bypass capacitor even with HAL-switched, some need a little capacitor from output to ground too, even though it seems counter intuitive on OC-output.
I am surprised that you got away without degausing the toroid.
Did you got a whole lot of noise from the output even without the toroid? Did it had chopper or auto-zero artefacts?
Pekka
efrench:
My Consew CSM1000 servo uses a hall effect sensor to control the speed. It might be worth looking at.
angus:
I have a fluke ma meter that must use the same principle.?. Does up to 25 ma dc
eskoilola:
--- Quote from: efrench on May 23, 2018, 09:47:18 PM ---My Consew CSM1000 servo uses a hall effect sensor to control the speed. It might be worth looking at.
--- End quote ---
In that application it is not nessecary to measure the current. t is sufficient to know whether the sensor is near some object or not. The speed is the of course a series of pulses that can be converted into speed by counting and dividing by time.
eskoilola:
--- Quote from: PekkaNF on May 23, 2018, 04:16:50 PM ---I am surprised that you got away without degausing the toroid.
Did you got a whole lot of noise from the output even without the toroid? Did it had chopper or auto-zero artefacts?
Pekka
--- End quote ---
Actually I did not get away. The mild steel was the only one that did not need to be degaussed but even that gave erratic results. The major factor was the earth magnetic field. When one has a gap in a toroid it immediately starts picking up unwanted magnetic fields. For this reason I had a calibration phase when all the 12 sensors figured out their zeroes. The best results were obtained by first cutting off the solar panels, then eating a nice dinner with the friend and after two hours or more just run the calibration. Degaussing was not an option as it totally removes any magnetism from the iron. Somehow the earth magnetism seemed to cumulate into the toroid... I was pretty overwhelmed with the behaviour until I realized that the orientation of the sensors had a lot to do on how they behaved. It did not become perfect. The measurement was reliable to 200mA. In this application it was good enough.
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