operating current

Hello everyone ,
Can I use an old mobile phone charger output 5v ,2A with the Arduino Uno or not !

I'm afraid that the regulator will not be able to handle it and will be fired

Is that ok to work or it's just a bad idea please help me !...

You can safely use it. Circuits draw the current they require.

However, 5 V has to be supplied to Vcc input, not the barrel jack or the RAW power input, as those require 7 V minimum on a typical Arduino. In that case the voltage regulator is not used.

Ok thank you sir

If you have regulated 5volt, then connect it to the 5volt pin (VCC) or to the USB socket.
That bypasses the onboard 5volt regulator.

Best to connect a 5volt phone charger to the USB socket.
Then you also have the protection of an onboard 500mA inline polyfuse.
Leo..

That could be a bad idea, many phone chargers have a fairly wide voltage range, they are designed to charge batteries not power computers. You can get a 12V 2A wall wart on ebay for a few dollars.
Good Luck, Have Fun! Gil

gilshultz:
That could be a bad idea, many phone chargers have a fairly wide voltage range, they are designed to charge batteries not power computers. You can get a 12V 2A wall wart on ebay for a few dollars.

Should have said cellphone chargers, but I think most of us will understand that nowadays.

5volt cellphone chargers with a USB socket or USB lead do not have a wide voltage range.
They are regulated, and almost exactly 5volt. Perfect to connect directly to the USB socket of an Uno.

Note that you can't draw more than 100mA total from any pin if you use a 12volt supply on the DC socket.
Otherwise the 5volt regulator will overheat and shut down (if you're lucky).
Leo..