Powering LED strip and Arduino

I am working on the digital clock Project where I build four 7-digit Displays based on the 28 individually addressed leds (cut from the LED Strip)
To build the prototype powering is easy.
I power arduino via USB and have a separate 5v power supply for the LEDs.
However when I finish the Project I would like to have a single power supply for the whole Thing.
I have 9v DC power supply cable. How can arranging powering both arduino and LEDs from it.

Would following Approach work.

  • I connect cables to +9v and GND of power siupply and then to Arduino via DC Adapter
  • I connect Voltage step down module to +9v and GND of the power supply , stap down to 5 v and via capacitor power 28 leds connected together

It would work but it is too complex.

Get a 5V regulated power supply, connect it to both the Arduino’s 5V pin and the LEDs, same with the ground. You always need a large capacitor on the strip an a resistor in line with the Arduino’s data pin.

I always thought Arduino 5v pin is regulated voltage output, and to imput voltage you use vin pin (9v). Can you confirm which pin i should use?
If I use 5v 1A dc power adapter would this work.

I always thought Arduino 5v pin is regulated voltage output

It is but basically it is a connection to the 5V line in the processor circuit so power can go in or out.
I power most of my projects through the 5V pin when an external supply is needed.

and to imput voltage you use vin pin (9v).

Yes you can do that, but you can power the whole thing with 5V. To be ultra fussy you can connect Vin to the 5V pin but you have to watch if you do you never to connect any thing to the power jack.

If I use 5v 1A dc power adapter would this work.

Well at full white an LED takes about 60mA, so 28 * 60 = 1.68A so I would go with a 2A power adapter. You might say you will keep the brightness down but these LED addressable strips can power up in any state so you can't rely on software keeping the brightness down.

Dziubym:
I always thought Arduino 5v pin is regulated voltage output, and to input voltage you use vin pin (9v).

No, it is a reference voltage output, only for powering sensors which use a few milliamps each.

This is because the on-board regulator has minimal heatsinking and if more than maybe 150 mA total is drawn, will overheat and (hopefully) shut down.

Dziubym:
If I use 5v 1A DC power adapter would this work.

Supplied to the 5 V pin, excellent.

The only warning is that there may be some danger powering the board from 5 V if you have the USB input connected to a computer for program upload because the 5 V may feed back into the PC USB and cause trouble.

This is not particularly likely, because virtually all inexpensive powered USB hubs do exactly that and rarely cause problems. Just in case, disconnect your 5 V while programming.