Can a Hall sensor accurately calculate magnetic north for an LED board?

[purejoker]

hi there, hope I am posting in the right place...

im trying to calculate the direction of magnetic north, using electronic curcuits.
what i want to do is have a board with a circle of led lights and when i place the board in different places; the light pointting to the direction of north should light up.

i can work out all the electronic, what I am stuck with is how to calculate the magnetic north.
ive looked into fluxgate, but they are to diffcult to build, is there any way of doing this with a hall sensor, or any other components.

i just need a idea to get me going...

thanks alot...


regards
pure

 

[MATLABdude]

Digital compass IC?

http://www.honeywell.com/sites/portal?smap=aerospace&page=Magnetic-Sensors3&theme=T15&catID=CF84B17AB-A90F-716D-10BC-A1E75441138E&id=HC1804CFD-B573-C5B4-9C0B-92928030FAAD&sel=2&sel4=2

If that's a little too pricey, here's a cheaper (and less accurate) one:
http://www.hvwtech.com/products_list.asp?CatID=114&SubCatID=214

 

[mgb_phys]

Yes a linear hall effect sensor is fine.
If you want to just put the board down you need a 2d device (or two 1d devices at right angles) if you can rotate the board around and just find a maximum then you only need 1.

BUT the board must be horizontal - if you want this to work while tilted you have a much more complicated problem.

 

[purejoker]

if i use a hall sensor, that means i require a magnet. but then how do i get the direction of magnetic north?

thank for your ideas

pure!

 

[mgb_phys]

if i use a hall sensor, that means i require a magnet.

Your standing on it.

but then how do i get the direction of magnetic north?

Measure the X and Y magnetic fields from two sensors at right angles and take the arctan
Think about if the board was pointing North, the y sensor would read a maximum and the X sensor would read zero , if it was pointing east they would be the other way around.

 

[purejoker]

if i use one of these, will it do the job! if yes, which is the best to use??

http://www.dinsmoresensors.com/index.html

thanks
pure!

 

[MATLABdude]

if i use one of these, will it do the job! if yes, which is the best to use??

http://www.dinsmoresensors.com/index.html

thanks
pure!

Sure, but it depends on whether you're happy with 8 directions (the digital one), or if you need finer grain resolution (via an A/D converter). Not that you necessarily get a result that's any more accurate, however (the specs seem kind of sparse). If you choose one of the analog ones, note that one (the 1525) has a lower voltage swing than the other (1655). That means that you get less of a voltage change between, say, north and south.