You may want to read Atmel application notes AVR-040 EMC design considerations and AVR-042 Hardware Design considerations. Of course they apply to Arduino. They might answer more questions than you stated You can download them from Atmel's website for free.Udo
relatively low DC voltages/current on a 2-sided PCB (say, 15V@3A max),
've been confused by talk of 'isolation', which I assume refers to using mosfets, diodes, etc to ensure their positive voltages are isolated.
if I connected the shield to more than one arduino ground pin, would that potentially cause a loop
Is it advisable to add a small resistor on the 0V DC connections from battery and DC supplies?
is it good/bad/indifferent to connect the PCB's ground to the chassis (in one place only)?