Compass unaffected by dc brush motors

[thaisonle]

Hi, my class is building a rov for a competition. One of the tasks to to find a the orientation of a shipwreck. We tried a few compasses and they all pointed to the rov within 2 feet of it. Its because the motors give off a magnetic field. We were gonna switch to brushless dc motors but that would kill our budget. Do anyone have any ideas to help us? It could be ANYTHING, digital or analog. Store bought or hand built.
Thanks,

[derelicte]

shut the motors off when you are taking a measurement. you should be able to eliminate the effect of the magnets by calibration and/or placement.

[reHosea]

I've used a Dinsmore 1525 Analog compass from http://www.dinsmoresensors.com/ which was coupled to a picprocessor, and it wasn't effected by the six DC motors that were in close proximity to it. The motors were not brushless motors either, just standard 12v motors.

[thaisonle]

Even with the motors off the compass still doesn't work. We're gonna try that Dinsmore analog.
Thank you so much for the replies,

[derelicte]

Even with the motors off the compass still doesn't work.

I'd say you have issues with that compass.