Hi, i was looking my arduino UNO board and i saw a little yellow component which i can't identify or find information about it. It's just aside the USB port, is like this one:
but mine say "505Y", googling i found some others that say "500Z", "510K" "1905", and even some green coloured, but none information about it.
Does anyone know what it's and which is it purpose?
Thanks!
Polyfuse.
500mA auto-reset fuse to protect the 5volt power line coming from the PC/laptop.
Leo..
Hi,
Tom... 
I see, also known as Resettable Fuse (in case someone else want to read about it)
Wawa:
to protect the 5volt power line coming from the PC/laptop.
This mean if i build a circuit very badly and it turn in shorts or something the USB port will be safe right?
Interesting factoid about this part:
https://www.arduino.cc/en/Products/Counterfeit
Here's a major fake-alert! The component 501 K located next to the voltage regulator is generally green on fake boards. The green one has similar properties as the original Arduino golden-black component and is available off the shelf.
We get it specially made for Arduino to make it look different:
Original board
Counterfeit
I believe the gold one with the infinity symbol or 8 on it in the picture you posted is their new custom PTC and they just haven't updated that webpage accordingly.
