Hall effect sensor

L

lerameur

Guest
Hello

I hope I can clear up some confusion about reading specification sheet
on hall sensor.
First the UGN3503U chip. on the web page
http://web-ee.com/schematics/instrumentation/build-gaussmeter/
the author calculates the Gauss with the following equation:

The hall effect device has a sensitivity of 2.5mV/G which, when you
invert
it, is 1G/2.5mV or (multiplying top and bottom by 1000) 1000G/V.
Now, you need to find out how many volts the output changed.
It changed (2.48-4.56)V = -2.08V. So, we end up with B = -2.08V *
1000G/V =
-2080G, and it is a South pole since it is negative.


it makes sense so far because the spec sheet do not tell us anything
about the maximum Gauss (voltage output) or could it be the maximum
sensitivity ( 900Gauss).

Now take a look at the ss495 chip , the spec sheet shows a graph from
-640 to 640 Gauss, But from the calculation above we would get a swing
of -1600 to +1600 Gauss.
Do we choose the graph or the mV/Gauss approach ? which one is
correct?

K
 
On Thu, 22 May 2008 07:25:16 -0700 (PDT), lerameur
<lerameur@yahoo.com> wrote:

Hello

I hope I can clear up some confusion about reading specification sheet
on hall sensor.
First the UGN3503U chip. on the web page
http://web-ee.com/schematics/instrumentation/build-gaussmeter/
the author calculates the Gauss with the following equation:

The hall effect device has a sensitivity of 2.5mV/G which, when you
invert
it, is 1G/2.5mV or (multiplying top and bottom by 1000) 1000G/V.
Click to expand...
Math error - I make it 400 G/V, not 1000G/V.


--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
 
On May 22, 1:09 pm, Peter Bennett <pete...@somewhere.invalid> wrote:
On Thu, 22 May 2008 07:25:16 -0700 (PDT), lerameur

leram...@yahoo.com> wrote:
Hello

I hope I can clear up some confusion about reading specification sheet
on hall sensor.
First the UGN3503U chip. on the web page
http://web-ee.com/schematics/instrumentation/build-gaussmeter/
the author calculates the Gauss with the following equation:

The hall effect device has a sensitivity of 2.5mV/G which, when you
invert
it, is 1G/2.5mV or (multiplying top and bottom by 1000) 1000G/V.

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

--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info:http://vancouver-webpages.com/peter
Vancouver Power Squadron:http://vancouver.powersquadron.ca
Click to expand...
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
 
<snip>
The hall effect device has a sensitivity of 2.5mV/G which, when you
invert
it, is 1G/2.5mV or (multiplying top and bottom by 1000) 1000G/V.
Now, you need to find out how many volts the output changed.
It changed (2.48-4.56)V = -2.08V. So, we end up with B = -2.08V *
1000G/V =
-2080G, and it is a South pole since it is negative.


it makes sense so far because the spec sheet do not tell us anything
about the maximum Gauss (voltage output) or could it be the maximum
sensitivity ( 900Gauss).
Click to expand...
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.

Now take a look at the ss495 chip , the spec sheet shows a graph from
-640 to 640 Gauss, But from the calculation above we would get a swing
of -1600 to +1600 Gauss.
Do we choose the graph or the mV/Gauss approach ? which one is
correct?

The SS495 datasheet clearly specifies a range of +-670G with with a sensitivity of 3.125mV/G
Click to expand...
-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)
 
<snip>

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
Click to expand...
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)
 
On Fri, 23 May 2008 12:39:18 -0400, Mike <nomtrxspam@comcast.net>
wrote:

snip

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)
Click to expand...
"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
 
On May 23, 9:06 am, Mike <nomtrxs...@comcast.net> wrote:
snip

The hall effect device has a sensitivity of 2.5mV/G which, when you
invert
it, is 1G/2.5mV or (multiplying top and bottom by 1000) 1000G/V.
Now, you need to find out how many volts the output changed.
It changed (2.48-4.56)V = -2.08V. So, we end up with B = -2.08V *
1000G/V =
-2080G, and it is a South pole since it is negative.

it makes sense so far because the spec sheet do not tell us anything
about the maximum Gauss (voltage output) or could it be the maximum
sensitivity ( 900Gauss).

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.



Now take a look at the ss495 chip , the spec sheet shows a graph from
-640 to 640 Gauss, But from the calculation above we would get a swing
of -1600 to +1600 Gauss.
Do we choose the graph or the mV/Gauss approach ? which one is
correct?

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)
Click to expand...
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
 
"Rich Webb" <bbew.ar@mapson.nozirev.ten> wrote in message
news:8qtd34l16ujkvhrmindt9u7eqom9so5765@4ax.com...
On Fri, 23 May 2008 12:39:18 -0400, Mike <nomtrxspam@comcast.net
wrote:

snip

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)

"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
Click to expand...

That reminds me:

Quoted from here:
http://math.bu.edu/people/jeffs/mathematicians.html

'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
 
On May 23, 9:06 am, Mike <nomtrxs...@comcast.net> wrote:
snip

The hall effect device has a sensitivity of 2.5mV/G which, when you
invert
it, is 1G/2.5mV or (multiplying top and bottom by 1000) 1000G/V.
Now, you need to find out how many volts the output changed.
It changed (2.48-4.56)V = -2.08V. So, we end up with B = -2.08V *
1000G/V =
-2080G, and it is a South pole since it is negative.

it makes sense so far because the spec sheet do not tell us anything
about the maximum Gauss (voltage output) or could it be the maximum
sensitivity ( 900Gauss).

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.



Now take a look at the ss495 chip , the spec sheet shows a graph from
-640 to 640 Gauss, But from the calculation above we would get a swing
of -1600 to +1600 Gauss.
Do we choose the graph or the mV/Gauss approach ? which one is
correct?

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)
Click to expand...
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
 
On May 23, 9:10 am, lerameur <leram...@yahoo.com> wrote:

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