Hall effect sensor

Math error - I make it 400 G/V, not 1000G/V.

--
Peter Bennett, VE7CEI  
peterbb4 (at) interchange.ubc.ca  
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thats nice, but if you do the same type of calculation on the ss495 chip, you get 1600G at 5v and they have a graph showing 640Gauss at

4.5 volt. That is where my confusion lies.

ken

The UGN3503U datasheet I'm looking at specifies a sensitivity of 1.3mV/G over the range of +-900G If you exceed 900G the response will become nonlinear.

-2.08V/1.3mV/G = 1600G. Which would be well above the linear range.

The SS495 datasheet clearly specifies a range of +-670G with with a sensitivity of 3.125mV/G

-2.08V/3.125mV/G = -665.6G

Looking at the graph in the SS495 datasheet I see an output voltage of 4.5V at

640G, so (4.5-2.5)/640 = 3.125mV/G which is what the datasheet specifies for the sensitivity.

The UGN3503U datasheet I saw doesn't have a graph like that.

Neither of the sensors you mention has the required range to directly measure rare earth magnets. The field at the surface of those can easily exceed 900G. Take a look at the Honeywell SS94A2E if that's a problem.

One of the Gaussmeters I used to make used a Honeywell sensor and a dual opamp to subtract the Vcc/2 offset and scale the output for direct readout on a panel meter. Another used an A/D with the math done in software. Either way works pretty well.

Mike

"In view of such harmony in the cosmos which I, with my limited human mind, am able to recognize, there are yet people who say there is no God. But what really makes me angry is that they quote me for the support of such views." Albert Einstein (theoretical Physicist)

the range of +-900G

sensitivity of 3.125mV/G

640G, so

sensitivity.

rare earth magnets.

Honeywell SS94A2E

to subtract

Another used

The Honeywell SS94A2E does not seem to be able to take more then

1000G Anybody know of a hall sensor that can read up to or about 10 000G

ken

the range of +-900G

sensitivity of 3.125mV/G

640G, so

sensitivity.

rare earth magnets.

Honeywell SS94A2E

to subtract

Another used

The Honeywell SS94A2E does not seem to be able to take more then

1000G Anybody know of a hall sensor that can read up to or about 10 000G

ken

Hmm, The SS94 series datasheet clearly shows 0.5mV/G over a +-5000 Gauss range for the A2E, still well short of the 10KG you need. I'm not up on the physics, but perhaps it's possible to build a probe that shunts half the field around the sensor.

Mike

"In view of such harmony in the cosmos which I, with my limited human mind, am able to recognize, there are yet people who say there is no God. But what really makes me angry is that they quote me for the support of such views." Albert Einstein (theoretical Physicist)

shunts half

"The word God is for me nothing more than the expression and product of human weaknesses, the Bible a collection of honourable, but still primitive legends which are nevertheless pretty childish. No interpretation no matter how subtle can (for me) change this. ... For me the Jewish religion like all other religions is an incarnation of the most childish superstitions. " Albert Einstein (theoretical Physicist), 1954

--
Rich Webb     Norfolk, VA

That reminds me:

Quoted from here:

'Laplace, Pierre Simon: French mathematician who usually receives credit for proving the stability of the solar system. In my thesis I suggest that it was Lagrange who actually did so. Though I have not been able to demonstrate this yet, I think it was Laplace's writing of Celestial Mechanics, an enormous, five volume tome of celestial mechanics, that established him as the Prince of Celestial Mechanicians. When presented with a copy of some of the initial volumes, Napoleon is said to have remarked, "I see no mention of God in this work". Laplace is said to have replied, "Sir, I have no need of that hypothesis." (In an addition to the story, the tale was related to Lagrange, who added "Ah, but it is such a beautiful hypothesis; it explains a great many things!"'

Regards, Bob Monsen

Sure, just use a discrete hall sensor instead of a preamplified IC sensor. They exist, if only for lab experimentation. It just takes a bar of semiconductor with two side-mounted sense contacts and two end-mounted current contacts.

A raw Hall sensor isn't much use, though, without current regulation and lots of voltage amplification. The IC sensors are all designed for real-world static fields (and 5000 Gauss is plenty of range for that). Pulsed electromagnets can get higher than this, but a simple test coil is accurate when measuring a pulse - no need for fancy Hall probes.