I’ve gotten to the point in my project where I’m cutting holes in my project box for cabling. I’m realizing I have some questions about noise, insulation, isolation, magnetic field intensity.
Specifically, what measures (if any) do I need to separate/insulate the high current carrying conductors from the analog signal carrying conductors?
My project includes…
6 x 1amp @ 12V solenoids switched by MOSFETs
2 x 2amp @ 12V heater circuits
multiple 5 V signals passed in/out between Arduino and other digital logic devices and sensors (analog).
I’ve calculated the magnetic field intensity for some of the higher current conductors (ground sink for the solenoids in particular) at a distance of 1mm (est. of AWG 20 w insulation):
B = mu_not / (2*pi) * I/d = 1.2E-3 Tesla
mu_not = magnetic field constant = 1.26E-6
I = 6A
d = 0.001m
This is unfamiliar territory to me. Is this a correct calculation? Is this magnitude of magnetic field small/tiny/medium/other? I need to consider what voltage levels could be coupled onto adjacent conductors from this magnetic field expanding and collapsing while the Solenoids are switched.
My thoughts: I found reference that the earth’s magnetic field is on the order of 10^-5 Tesla. This magnetic field is 100 X larger @ 1mm from the conductor. To me this sounds negligible.