Powering arduino with adapter

Projects General Guidance
1

Hello,

  • I recently bought a 2 meter WS2812B LED strip that takes about 7,2A (max).

I would like to also power my Arduino Uno with a 5V DC 10A adapter, I use the adapter to give power to the LED strip and the Arduino, now I've actually never thinked about this but I have to put the + (5V) side into the Vin arduino pin right? And not just a normal 5V pin?

Also I've read things that this is bad for your Arduino? Is this true? If so why, and what would you recommend me!

  • 1 more question, if I want to connect the Arduino with LED strip I have to attach the + and the - both to the LED strip and the Arduino.
    And if I want to power the Arduino by USB (for Serial data), I have to connect + - from adapter to LED strip, - from adapter to Arduino and just leave the +. So basically I connect only grounds to each other and not the +, I just leave that empty.
    Is that correct?

If I forgot something to mention please tell me!

Thanks!

2

The VIN pin is just an alternative to the barrel jack and requires 7 to 12v. It is also used to supply the 7-12v to other shields, like the Ethernet shield. If your 5v supply is kosher 5v you can apply it to the 5v pin. You just need to be aware that you are bypassing the regulator.

3

Oh.. well I have a 5V adapter and the LED strips also uses 5V... so I can just connect this to a normal 5V pin to power the board.

But what will damage the board without a regulator? Like how could I damage it and such?

4

akatchi:
Like how could I damage it and such?

Most likely if your 5v power supply is not strictly regulated to a max of 5v. A bit lower than 5v won't be a problem.

...R

5

I would like to also power my Arduino Uno with a 5V DC 10A adapter, I use the adapter to give power to the LED strip and the Arduino, now I've actually never thinked about this but I have to put the + (5V) side into the Vin arduino pin right? And not just a normal 5V pin?

Yes. The 5V pin bypasses the on-board voltage regulator.

Also I've read things that this is bad for your Arduino? Is this true? If so why, and what would you recommend me!

I guess the "danger" is that you don't have the voltage-regulator in series to protect the Arduino. If something goes wrong with the power supply (or if you have something inductive like a motor attached) and you get a voltage-spike you can over-voltage your Arduino.

  • 1 more question, if I want to connect the Arduino with LED strip I have to attach the + and the - both to the LED strip and the Arduino.
    And if I want to power the Arduino by USB (for Serial data), I have to connect + - from adapter to LED strip, - from adapter to Arduino and just leave the +. So basically I connect only grounds to each other and not the +, I just leave that empty.
    Is that correct?

Yes. Both the LED strip and the Arduino need power and ground. They can (optionally) have separate power sources, but they need to share a common ground because the "control signals" need a common reference.

6

You can add a diode from 5V to Vin to help protect the regulator - anode to +5, cathode to Vin (so Vin is a voltage drop below 5V). Keeps the regulator from being reverse driven. The regulators on the old Duemilanove seemed sturdier, the NXP1117 used now not as much.

7

"The VIN pin is just an alternative to the barrel jack and requires 7 to 12v. "
Vin also bypass the reverse polarity protection diode, so be sure not to get 5V & Gnd reversed.

8

Thanks for all the help!

DVDdoug:
If something goes wrong with the power supply (or if you have something inductive like a motor attached) and you get a voltage-spike you can over-voltage your Arduino.

I have 1 data pin connected to my Arduino to the led strip

  • LCD 20x4 (I2C)
  • NRF24L01
  • Bluetooth module
  • Speaker (simple buzzer)
  • Motion sensor
  • IR-receiver
  • RFID reader
  • Photoresistor

That's what I have connected to my Arduino and what I want to power with it.. if this causes problems I could also only try an arduino with the data pin to the LED strip, will that cause problems too?

CrossRoads:
"The VIN pin is just an alternative to the barrel jack and requires 7 to 12v. "
Vin also bypass the reverse polarity protection diode, so be sure not to get 5V & Gnd reversed.

Thanks for clearing that out!