General tips on reducing magnetic interference?

Hi everyone,
I have a craft that flies fine on its own. I have printed a small flashlight (a PCB with 16 small LEDs, a battery, two short wires and some steel screws to keep it together), and the compass becomes less happy when I mount it on the quad.

I have two questions: What exactly is affecting the compass reading, and how can I reduce interference? Unfortunately I can’t put the flashlight farther away due to the design, but is there anything else I can do?

What is the biggest culprit here? The steel screws, the battery, the PCB or the current running in the system? How can I mitigate things?

I’d appreciate any knowledge on this, thanks!

you want to avoid the interference of other magnetic fields other than the earth, and get to capture this as best as possible.
first, do not put any ferromagnetic or metal objects near the compas. This can divert the natural magnetic field of the earth in an “unnatural”, unwanted direction,

keep the compass and its data cables (at least 15cm), any cable that is powered, and even data,
If this is not possible, then use coaxial cables or intertwine pairs of cables with their respective GND’s, to avoid loops that generate a distant magnetic field.

by last.
keep ESC away, all the power electronics, the compass and the gps need to be separated from practically all the electronic modules of the device even electronic low power, since the pcbs themselves are metal plates that with their movement relative to the fields Magnetic can self-induce and therefore modify the surrounding magnetic field.

So in summary:

move metal parts away

removes cables and batteries

interlace the power cables with their respective grounds
and sign the signal cables with their respective grounds

to say that the compas must be well attached to the fuselage of the device

if you are more interesed please se these 3 videos



This is fantastic information, thank you very much! I followed your advice and it improved the noise situation greatly, thanks again!

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what version of copter do you have?

The latest one, 3.4.6 I believe.

i have a problem with the do set servo comand in ac 3.6 dev
the servo work wen i clik the button in the mission planner test panel servo.
but if i do a mission, the servo dont work…