this turns on the pullup resistors on the digital ios, so maybe without those there may be interferences !
ok, but i already have several external pulldown resistor like this:
the only diference is 10K was very sensitive for me, so i changed for 1k and works perfectly
- remove the external resistors
- change the if condition (digitalRead(x) == DOWN)
- change the side of the button which is connected in vcc to gnd
I brought one of them to my house to try again and put in a multiple plug my pc, a little stereo, my cellphone, an old bubble light, a floor fan in maximum speed and the arduino powered with the first cheap charger.
I turn everything on and off several times (i know it was dangerous for de devices, but i had to clear my doubt, and nothing mess up :) ) and the arduino works perfectly, doesn't fail any single time
so, the only i can think is that the electrical instalation of the house where it fails is really bad. now i remember that while are making the instalation of these arduinos, when we used the drill all the lights lose a little of intensity