# How many A requires my project ?

Hello there, today i got my arduino uno ! Great success with the blink example YEEEEEEEEAHH :P , but now lets go to some serious (just for me) issues. My project will require an external power supply , i cant have arduino connected to usb cable, so im searching an external power supply !

I will use : (at the right im writing the V and A i THINK each piece wants)

1x - https://www.sparkfun.com/products/11021 5V @ ?A (im not sure for 5V either , it says 7-12V but usb is 5V right ? why external of 5V whouldn't work ?) 2x - https://www.sparkfun.com/products/9648 5V@0.2A x 2 = 5V@0.4A 2x - https://www.sparkfun.com/products/10167 5V@0.0016A x 2 = 5V@0.0032A 1x - https://www.sparkfun.com/products/9395 5V@ up to 1A , so 1A 1x - https://www.sparkfun.com/products/8653 5V@?A 1x - https://www.sparkfun.com/products/9607 3.6V@2A - here it says to put 5V http://tronixstuff.wordpress.com/2011/01/19/tutorial-arduino-and-gsm-cellular-part-one/ 40x - https://www.sparkfun.com/products/9590 2.2V@0.02A x 40 = 2.2V@0.8A , through https://www.sparkfun.com/products/733

Future thoughts :

Non-Future thoughts = ?+0.4+0.0032+1+?+2+0.8 = 4.2A Future thoughts = 4.2 + 0.7 = 4.9A

In order to get 3.6V and 2.2V i will use some kind of regulator or another 2 different power supplies ? THANKS !

why external of 5V whouldn’t work ?)

Because that value of 7 - 12V is the voltage to the power jack. If you want to power it off 5V then feed it direct to the +5V pin on the arduino.

Just add up all the currents and that is the minimum you need. If you don’t know the current of each device then you can’t work it out. You will have to measure it.

In order to get 3.6V and 2.2V i will use some kind of resistors or another 2 different power supplies

No you can not use resistors. You can use voltage regulators to get these lower voltages from the 5V line.

I reuse laptop or cell phone charger power supplies - have tons of the laying around. You can also ruse an atx power supply.

The arduino itself doesn’t consume much current (on the order of ma). So pretty much anything will do. You will need to figure out your future peripherals and how much they consume.

In order to get 3.6V and 2.2V i will use some kind of regulator or another 2 different power supplies ?

You can but that requires some low value resistors so it may not be terribly efficient.

invader7: In order to get 3.6V and 2.2V i will use some kind of regulator or another 2 different power supplies ? THANKS !

The product page for the Cellular Shield says it's 3.8V and it has its own regulator.

For 2.2V...just don't go down that road. Read one of the many threads on LED voltage/current for how to power LEDs correctly.

fungus: The product page for the Cellular Shield says it's 3.8V and it has its own regulator.

So 5V as mentioned to the tutorial i posted , are ok for this too ! 1.2V wont overheat its regulator i think...

If i buy a simple pc power supply and turn it on by connecting black and green wire together (common power supplies colors for this trick) , the 5V from the red (common 5V cable) will be safe enough for my project leds servo sensors lcd etc ??? I show a lot of guides , some of them made it so easy as i described it and some other followed the hard way soldering resistors etc to their power supplies , it will work as simple as connecting black and green cable ? thanks !

It will automatically power up the arduino , so after the black-green connection is made (maybe i put a switch there) it will have load at no time.