Cheap digital compass

[Mosaic]

Ok, I need a rough digital magnetic direction finder.

I am considering using an actual compass such as this:
**broken link removed**

Compass needle sensed by a linear hall sensor, perhaps this:
https://www.jameco.com/Jameco/Products/ProdDS/1915940.pdf

Hall signal fed to a PIC ADC.
I am thinking I could profile the ADC values to reflect the compass needles orientation and thus be able to derive a passable direction finder perhaps +/- 5° (a guesstimate). Also by tracking turn direction I could differentiate between the two perpendicular orientations of the needle to the hall sensor.

I haven't tried to evaluate the gauss of a compass needle magnet , but it should be of reasonable strength to work with I think.
Sounds doable?

 

[debe]

Google Flux Gate sensor no moving parts. This is what some auto pilots use, as well as digital compases. They sense the earths magnetic field rather than use a magnetic compass.

 

[Mosaic]

$1K per piece is not cheap....

 

[Nigel Goodwin]

How about this:

**broken link removed**

 

[jpanhalt]

Here's another option: https://www.digikey.com/product-detail/en/HMC1051Z-RC/342-1034-5-ND/409394

And a Microchip pretty good ap note to go with it: https://ww1.microchip.com/downloads/en/AppNotes/00996a.pdf

John

 

[Mosaic]

Ok, I ordered the bang good module....seems worth it as a building block.
The part jpanhalt mentioned is on sale @ Newark.
https://www.newark.com/honeywell-m-ps/hmc1021z-rc/magnetic-sensor/dp/50M1777

But for now I prefer the module as I am making a kit that could use it as an optional plug in add on.

 

[gary350]

A magnetic needle compass is very sensitive to metal objects I have one for camping and hiking. The needle gets all crazy from the metal on my belt buckel and I need to be 50 feet from my vehicle to get an accurate reading. The larger the metal object is the farther away you need to be from it. A cheapo kids toy compass is less sensitive to metal objects than a nice Boy Scout compass. You can use a cheapo compass to find nails in the wall but you can not do that with a good compass it finds every pieces of metal in the whole house and the needle goes crazy.

 

[Mosaic]

That's strange...I have a needle compass on my car's dashboard and it works fine.

 

[dr pepper]

I dont know if the hall sensor sould generate a field and mess up a compass, doesnt matter now.

I have developed a project using a i2c compass module, they are 3 quid each, the circuit generates the heading from x and y vectors.
The maths involved gets complicated, you get x and y readings from the magnetometer, which are vector variables, and you need to convert them to a polar heading, tricky stuff.
There are some examples on the net using lookup tables.
My circuit produces a heading in degrees so might be over accurate, you might be able to use something simpler to get a rough heading.

If yu look through my posts someone here gave me guidance and some pic code a while back.