Cui

Hi all,
I am building this usb interface given here:
**broken link removed**
There is one PTC fuse used n the circuit. From what I could make out by googling for the thing is that it protects a circuit from high current by increasing resistance. I could not find it anywhere. Now, is this part absolutely necessary or it could be done away with. Does anyone know?
Samar

It's basically only a fuse, included to help protect your PC if you short the 5V out - it will work fine without it, but you lose that layer of protection.