calibrate magnetic sensors
calibrate magnetic sensors
(OP)
I am looking for an a product to produce predictable field intensity to be used to calibrate hall sensors ideally up to 3T (30,000 Gauss)
I would like it adjustable.
I am thinking of something like a "C" shaped core with a gap into which the sensor is placed and a coil driven by DC current.
Thanks
I would like it adjustable.
I am thinking of something like a "C" shaped core with a gap into which the sensor is placed and a coil driven by DC current.
Thanks





RE: calibrate magnetic sensors
I suppose that you could build an electromagnet and use a high precision DC power supply to drive it.
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Plymouth Tube
RE: calibrate magnetic sensors
TTFN
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RE: calibrate magnetic sensors
Could you tell me where to get PM based system? Might do in some application.
Thanks
RE: calibrate magnetic sensors
A number of gaussmeter manufacturers (particularly ones that make laboratory quality instruments) offer reference magnets. Here are some links:
http://www.lakeshore.com/mag/ga/gm410oi.html
http://ww
I have a few old ones from Walker (not sure if they make them any more), but usually reference magnets only go up to a few thousand gauss. Beyond that, you'll need a full electromagnet (Helmholz coils can only produce a 1 to 2 kGauss). However, 30,000 Gauss in an electromagnet will be tough to produce.
Just a few months ago my company made a 30,000 Gauss (3 Tesla) permanent magnet dipole. It fits in the palm of your hand.
RE: calibrate magnetic sensors
I built 2T PM jobs in the past, so it isn't too great of a stretch. The problem is that is the active sensor area is 0.125" x 0.125", then you need good field uniformity over an area about 0.250" x 0.250". this implies that your pole faces need to be about 0.500" diameter. It ends up being larger than you would think at first.
At least with a cal magnet you only need an air gap of 0.125".
There are a couple of ways of building these. A "C" yolk is easiest. Putting the magnets and poles inside of a tubular return structure is better. No chance of picking up debris or of damage to the magnets. Just a little window cut in the side for insertion of the probe.
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Plymouth Tube
RE: calibrate magnetic sensors
AlanSimpson: to make your field source adjustable, you would need current in a coil. 3 T is larger than saturation level of steels, for example, 1018 steel is around 1.8 T. Thus the coil structure could not benefit much from steel and the electromagnet would have to basically have an "air" core. Thus, the ampere-turns required to produce your adjustable field would likely be large, making your electromagnet large and heavy. This is how it seems to me.
RE: calibrate magnetic sensors
RE: calibrate magnetic sensors
RE: calibrate magnetic sensors
I would suggest against using NdFe since the temp coef is so high. We could measure the changes based on the temperature of the room.
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Plymouth Tube
RE: calibrate magnetic sensors
The 3 Tesla dipole we constructed was not built as a reference magnet. That customer needed 3 Tesla minimum for their application and we achieved 3.1 Tesla in that design.