# Power adapter to power up multiple max7219 + bluetooth + uno

Hi
I am creating display based on arduino uno, currently i am using max7219 displays (8 of them)
I already managed to create an app for android to control max7219 display via bluetooth (from mobile i send text to the max7219 and it displays) but i dont understand how can i power up the whole system without burning anything.
I asked this question before and received alot of answers and i understanded the best choice is to use
9 to 12 V adapter. If i understanded correctly each max7219 display of my kind is using 500mA
The bluetooth module is using 30-40 mA during paring with device and 8 mA during communication.
I tried to powerup 5 displays from computer usb and everything worked fine tho.

If i will use for example 12v 10A power adapter, will everything be good?

And i would like to know, should i use resistors and capacitors? I
I read before that you should use 0.1uF capacitor per chip or 1 10uF cap per 3 matrix( soo 3 in total) and with resistors it was 3 100Ω for the whole project. But i am not sure about them, maybe i wont need them ( i read that information from a guy who made such display for his car and powered it from the car wires as understood)
Thanks

This kind of matrixis i use.

Decired:
If i understanded correctly each max7219 display of my kind is using 500mA

If i will use for example 12v 10A power adapter, will everything be good?

You have been told otherwise in your other thread.
Read reply #7 here.

These modules need 5volt, so how are you going to reduce that 12volt to 5volt.
Linear regulation to convert 12volt/10Amp to 5volt/10Amp would dissipate 70watt (big/hot heatsink).
A switching buck converter would be another module.
Maybe easier to use a 5volt/10Amp supply.
Leo..

Wawa:
You have been told otherwise in your other thread.
Read reply #7 here.

These modules need 5volt, so how are you going to reduce that 12volt to 5volt.
Linear regulation to convert 12volt/10Amp to 5volt/10Amp would dissipate 70watt (big/hot heatsink).
A switching buck converter would be another module.
Maybe easier to use a 5volt/10Amp supply.
Leo..

I understand that, but the wiki says that you need 9 to 12V to power up arduino.

Decired:
I understand that, but the wiki says that you need 9 to 12V to power up arduino.

What Wiki (link).

9volt is just ok, but 12volt is borderline for an Uno.
An Uno also can be powered with 5volt on the USB socket or on the 5volt pin.
Leo..