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Magnet measurement

K

Ken O

Jan 1, 1970
0
Hi,

Anyonw knows the best way to measure a magnet strenght? either permament or
electromagnet.
would it be with a galvanometer or is there anything else on the market.
thanks

Ken
 
Z

Zak

Jan 1, 1970
0
Ken said:
Anyonw knows the best way to measure a magnet strenght? either permament or
electromagnet.
would it be with a galvanometer or is there anything else on the market.

Nuclear magnetic resonance is very accurate I think...


Thomas
 
J

John Fields

Jan 1, 1970
0
Hi,

Anyonw knows the best way to measure a magnet strenght? either permament or
electromagnet.
would it be with a galvanometer or is there anything else on the market.
thanks
 
C

Chris

Jan 1, 1970
0
Ken said:
ya thats what i figured,
I am thinking of building one, I found this site
http://my.execpc.com/~rhoadley/magmeter.htm

I am finding out that hall effect sensors are very hard to find... its not a
hot item.


kenO

Hi, Ken-O. The reason you're having trouble finding the part is that
Radio Shack really doesn't carry very much in the way of components
these days, and also that the manufacturer is obsoleting the part.

The cross-reference is the Allegro A1321LUA-T. It operates on the same
voltages, same pinout, and has the same sensitivity (5mV/G). It's
available in stock at Digi-Key for $1.45 USD. And it has a working
temperature range from -40C to 150C, so it can be just about as hot an
item as you please.

http://www.allegromicro.com/datafile/1321.pdf
http://www.allegromicro.com/datafile/3515.pdf

Hope that helps. Book 'em.

Good luck
Chris
 
Ken, generally it's measure using a Gauss meter. Modern instrument
uses Hall Effect semiconductors for the purposes.

Harry C.
 
K

Ken O

Jan 1, 1970
0
Ken, generally it's measure using a Gauss meter. Modern instrument
uses Hall Effect semiconductors for the purposes.

ya , gauss meter at 500$, a little too steap for me. I thought of building
one.
looking into it

ken
 
K

Ken O

Jan 1, 1970
0
Chris said:
Hi, Ken-O. The reason you're having trouble finding the part is that
Radio Shack really doesn't carry very much in the way of components
these days, and also that the manufacturer is obsoleting the part.

The cross-reference is the Allegro A1321LUA-T. It operates on the same
voltages, same pinout, and has the same sensitivity (5mV/G). It's
available in stock at Digi-Key for $1.45 USD. And it has a working
temperature range from -40C to 150C, so it can be just about as hot an
item as you please.

http://www.allegromicro.com/datafile/1321.pdf
http://www.allegromicro.com/datafile/3515.pdf


thats exactly it, thanks a lot,
i did go on digikey website, I put hallsensor as a search keyword, and it
showed me the another ' apply filter page' i was never successful to get
those parts..
ken
 
J

Jamie

Jan 1, 1970
0
Ken said:
Hi,

Anyonw knows the best way to measure a magnet strenght? either permament or
electromagnet.
would it be with a galvanometer or is there anything else on the market.
thanks

Ken
go there.
your looking at a Gauss meter.
http://www.trifield.com/
http://www.trifield.com/gauss_meter.htm

in short, you can use Webers (Wb) as the
unit to measure with and that is.
1 weber = the magnetic flux that produces an
electromotive force of 1 volt in a 1 turn loop
circuit as the flux changes from max to 0 in
one second time.
 
D

Don Taylor

Jan 1, 1970
0
ya , gauss meter at 500$, a little too steap for me. I thought of building
one.
looking into it

You didn't say how accurate you needed the measurement to be.
If you don't need terrific accuracy and you like cheap...

How about using a compass? Put the magnet far away from your compass
and let the compass settle down.

Then bring the magnet closer but keep the magnet's field at right
angles to the direction your compass is pointing. Bring it close
enough that you see the compass needle deflect 45 degrees. At that
point you know that at that distance the field from your magnet is
approximately equal to the earth's magnetic field at your location.
(You can get values for the strength of the earth's magnetic field
near you from library references, or probably google, it seems to
have everything else)

This is lots cheaper than buying a gaussmeter, probably quicker to
get you an answer too. And it is easy to get an estimated value.
(but this trick isn't going to work for AC driven magnetic coils)
 
C

Chris

Jan 1, 1970
0
Ken said:
thats exactly it, thanks a lot,
i did go on digikey website, I put hallsensor as a search keyword, and it
showed me the another ' apply filter page' i was never successful to get
those parts..
ken

OK, Ken. Just for reference, if you're having trouble finding a
semiconductor, the first thing to do is go to the manufacturer's
website, and punch in the part number. Sometimes you get really bad
news, but sometimes you get some help. If you'd waited another year to
do the project, the part would have been gone, and the recommended
cross might not have been so easily found.

Worse comes to worst, you can always email or call the manufacturer's
sales engineers. They will recommend a cross (and frequently recommend
competitors' parts.

Good luck with your project -- it looks pretty straightforward. Feel
free to post again if you get hung up.

Cheers
Chris
 
Ken said:
ya , gauss meter at 500$, a little too steap for me. I thought of building
one.
looking into it




Really cheap Hall sensors (but SMT package):

Linear Hall sensor, two for $1.00
http://www.allelectronics.com/cgi-bin/item/SS-19T/search/HALL-EFFECT_MAGNETIC_POSITION_SENSOR_.html



Here's my list of more. (Old list, so those available from surplus
companies have changed.)

http://www.amasci.com/maglev/hall.html



For measuring less than a Gauss, here's an interesting circuit:

Sensitive geomagnetic detector

http://www.geocities.com/CapeCanaveral/Lab/5185/circuit1.html#SENSITIVE

((((((((((((((((((((((( ( ( (o) ) ) )))))))))))))))))))))))
William J. Beaty Research Engineer
[email protected] UW Chem Dept, Bagley Hall RM74
[email protected] Box 351700, Seattle, WA 98195-1700
ph425-222-5066 http//staff.washington.edu/wbeaty/
 
J

Jasen Betts

Jan 1, 1970
0
Hi,

Anyonw knows the best way to measure a magnet strenght? either permament or
electromagnet.
would it be with a galvanometer or is there anything else on the market.
thanks

you could try Hall effect ?
a lump of iron and a strain gague?

"best way" really depends on the expected strength
a micrometer is great for measuring he thickness of a pcb but not much
use mountains.


Bye.
Jasen
 
K

Ken O

Jan 1, 1970
0
You didn't say how accurate you needed the measurement to be.
If you don't need terrific accuracy and you like cheap...

How about using a compass? Put the magnet far away from your compass
and let the compass settle down.

Then bring the magnet closer but keep the magnet's field at right
angles to the direction your compass is pointing. Bring it close
enough that you see the compass needle deflect 45 degrees. At that
point you know that at that distance the field from your magnet is
approximately equal to the earth's magnetic field at your location.
(You can get values for the strength of the earth's magnetic field
near you from library references, or probably google, it seems to
have everything else)

This is lots cheaper than buying a gaussmeter, probably quicker to
get you an answer too. And it is easy to get an estimated value.
(but this trick isn't going to work for AC driven magnetic coils)

Actually I want to do different typr of coils, i need something to compare
strenght. So i do not really need the absolute value, but just an
indication what works best.

ken
 
M

Mike

Jan 1, 1970
0
Actually I want to do different typr of coils, i need something to compare
strenght. So i do not really need the absolute value, but just an
indication what works best.

ken

I have quit doing it now but, I have been building a little Guass
meter for several years that slotcar (remember those?) racers use to
test and match the little magnets in their motors. Yeah, a lot of
those guys are very serious about their racing. Anyway, I was able to
wholesale it for $150 so you should have no problem building one
yourself on the cheap. The units I made used a ratiometric sensor
similar to the ones that have been recommended. My earliest versions
used opamps to shift and scale the sensor output that fed a panel
meter module. The last ones I made used a sigma delta A/D and a PIC
driving a standard LCD. Either works just fine. All have used the same
sensor built into a traverse probe. The sensor cost me about $13 ea
and were never in stock so I always ordered 25 at a time. Whatever
sensor you use, make sure it stays linear throughout the range of the
field you expect to encounter. Most of those sensors will run out at
anywhere from +- 100-2500 Gauss. I don't know if repeatability is all
that important to you, but keep an eye on the temperature specs for
sensitivity, offset, and linearity.

Mike
 
J

Jasen Betts

Jan 1, 1970
0
Actually I want to do different typr of coils, i need something to compare
strenght. So i do not really need the absolute value, but just an
indication what works best.

use some sort of bridge, or balance, then.
 
D

Don A. Gilmore

Jan 1, 1970
0
Ken said:
Hi,

Anyonw knows the best way to measure a magnet strenght? either permament or
electromagnet.
would it be with a galvanometer or is there anything else on the market.
thanks


If by "strength" you mean "lifting strength", then field strength
doesn't necessarily tell you everything. A solenoid can have a strong
field, but it picks up nothing. The core is important.

The best way is probably an empirical one. Put a block of steel on a
scale and note its weight. Attach your magnet to it and lift up.
Watch closely and see what the scale reads just as the magnet breaks
loose. Subtract this number from the initial weight and this is how
much the magnet was lifting. Note that you may get a different amount
of lift using the side of a magnet than using the end, too.

Hope this helps.

Don
Kansas City
 
I

ian field

Jan 1, 1970
0
Chris said:
Hi, Ken-O. The reason you're having trouble finding the part is that
Radio Shack really doesn't carry very much in the way of components
these days, and also that the manufacturer is obsoleting the part.

The cross-reference is the Allegro A1321LUA-T. It operates on the same
voltages, same pinout, and has the same sensitivity (5mV/G). It's
available in stock at Digi-Key for $1.45 USD. And it has a working
temperature range from -40C to 150C, so it can be just about as hot an
item as you please.

http://www.allegromicro.com/datafile/1321.pdf
http://www.allegromicro.com/datafile/3515.pdf

Hope that helps. Book 'em.

Good luck
Chris

There's a couple of folders of datasheets at these links.

http://www.allegromicro.com/datafile/archive/
 
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