So I'm trying to protect a circuit board that is receiving 5V from a wire that passes by some noisy relays. If I pass the wire several times through a ferrite core and then into my circuit board, the AVR doesn't start up. If I remove the ferrite core, starts up just fine. There's voltage on the board as there is an LED that lights up just fine that taps into the 5V bus on the board but no dice on the AVR.
Anyone know why an inductor would do this? I thought it would just delay turnon my a few ms or something.