Power supply for 5v LED strip and UNO.

I’d like to get a LED strip to play with. I’m thinking of a 2m strip. I’d like to power it, and the Arduino - from a power supply. Would a 5v, 2amp power supply be enough to power both?

I was going to snip off the end of the power supply and add a connector that connects to something ( not sure what yet) on the board. And then another bit to connect to the strip/s. (I might snip the strip I to two and drive two strips).

So what would he power supply connect to on the board? Ground and Vin? And can you still connect the USB to upload sketches while the board is powered?

Or maybe the supply goes to the breadboard - and the bread board powers both the LED strips and the UNO?

5V, regulated works fine connencted directly to 5V-pin on arduinoboard.
The Vin-pin is to be used for 6.5V+

Ah thanks. So the 5v isn’t only voltage to the breadboard? It can be used to power the bots as well?


Don't pass the power through the Arduino board, or a breadboard. Neither are designed to handle high currents. Connect the power directly to the LEDs, and also take a second pair of wires to the Arduino.

You do not say what kind of led strip you want to buy. Many strips need a 12V supply. These come in single colour and RGB. To control these, you need to use pwm outputs from the Arduino and MOSFETs. You cannot control individual LEDs with these kinds of strips.

Strips that need a 5V supply are often the individually controllable RGB type referred to as NeoPixels. The most common type is ws2812b.

If ws2812b or similar is what you want, 2A will not be enough. It's not the length of the strip that is important, it's the number of LEDs on it. Strips can have anything from 30 to 144 LEDs per metre. 60 per metre is most common.

You need an amp for every 15 LEDs in theory, since each led can draw up to 60mA. In practice, you don't really want to go much beyond 80% of the power supply's capacity, so one amp for every 13 LEDs.

The Arduino, by itself, will need less power than one led.

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Sorry PaulRB - 'bots' should have read 'board'. :slight_smile:

The LED strip that I am looking at is the 5V ws2812b labelled version.

In particular, it's 30 leds / meter, and I am looking to power two strips of 50cm each. So, 15 leds on each strip - 30 leds in total. So, it sounds like, based on that, a 3A power supply might be sufficient to power the LEDs and the Arduino nano board (but initially testing with an UNO)?

Thanks for the advice on powering with the breadboard/Arduino.

So, I'd power the LEDs direct from the 5V power supply (+/-), and also power the Arduino?

I’d be basing it off this image, but a bit worried about how to not make magic smoke.

I think, when I am programming/testing, the power from the 5V adaptor must be removed, to allow the USB power/data to be connected. Also, as I’m pretty new to this, I’m not sure how to physically connecte the capacitor (or even, what it’s purpose is).

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Use a 1000uF (microFarad), not 1000mF (milliFarad)

1000uF = 1mF
1000mF = 1F

The diagram is fine (except for the error about the cap value) and shows how to connect the cap, which acts as a local power reservoir.