Can i use this AC-DC adapter safely for my Arduino?

Hi,

Before i destroy my Arduino UNO by connecting it to this adapter, i would like to ask if this adapter is safe to be used with my UNO? It connects to the mains and it outputs 12 V DC but it also says 2 A, which is what i'm worried about. Isn't that way above the current limit for the Arduino?

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Yes.
The power supply rating is what the power supply can put out if needed by the load. The Arduino will only take what it needs. In the case of the Uno, about one-amp.

I have powered arduinos from my workbench power supply which is capable of 30A.

12v to an Arduino is a bit high.

The on board regulator may run hot if you power too many devices from the Arduino’s 5v pin.

A power supply ~7 to 9VDC might be a better choice.

Powering through the USB port with a USB phone charger is also often an option.

get 5V 1A and power it off of it's 5 Vout pin ( yes 5V out as Input)

larryd:
12v to an Arduino is a bit high.

The on board regulator may run hot if you power too many devices from the Arduino’s 5v pin.

A power supply ~7 to 9VDC might be a better choice.

But from Arduino Uno Rev3 — Arduino Official Store tech specs:
Input Voltage (recommended) 7-12V
So, i think it should be fine?
And... Input Voltage (limit) 6-20V

Be for warned.

Power = Voltage x Current

The more power, the more heat.

If you give the Arduino regulator 12v, the voltage across the regulator is 12v - 5v = 7v.

If you were drawing 500mA from the power supply the regulator dissipates 7V x .5A = 3.5 watts.

3.5 watts will fry your regulator.

Now assume you use a 7V power supply. This means the regulator now has 7V - 5V = 2V across it.

If you use the same 500mA, the regulator dissipates 2V x .5A = 1 Watt.

Summary, we now have 1 watt (with a 7VDC power supply) where we had 3.5 watts (with a 12VDC power supply).

You can take your chances if you want, it’s all up to you :slight_smile: .

DryRun:
But from Arduino Uno Rev3 — Arduino Official Store tech specs:
Input Voltage (recommended) 7-12V

A very real danger is that the thoroughly obsolete tutorials on the Arduino site (written ten or more years ago and simply not updated) and others misleadingly imply that the largely ornamental "barrel jack" and "Vin" connections to the on-board regulator allow a usable source of 5 V power.

This is absolutely not the case. It is essentially only for demonstration use of the bare board back in the very beginning of the Arduino project - "back in the days" - when "9V" transformer-rectifier-capacitor power packs were common and this was a practical way to power a lone Arduino board for initial demonstration purposes. And even then it was limited because an unloaded 9 V transformer-rectifier-capacitor supply would generally provide over 12 V which the regulator could barely handle.

If you are asking this question, it is highly likely that you will wish to connect something else. In which case, the answer is regulated 5 V.

This is because the on-board regulator is essentially capable of powering only the microcontroller itself and no more than a couple of indicator LEDs. The on-board regulator might be able to power a few other things if it had a heatsink, but on the Arduinos, it does not.

Powering via the "barrel jack" or "Vin" connections is asking for trouble. The "5V" pin is not by any means an output pin, if anything a "reference" pin but most certainly the preferred pin to which to supply a regulated 5 V.

larryd:
Be for warned.

Power = Voltage x Current

The more power, the more heat.

If you give the Arduino regulator 12v, the voltage across the regulator is 12v - 5v = 7v.

If you were drawing 500mA from the power supply the regulator dissipates 7V x .5A = 3.5 watts.

3.5 watts will fry your regulator.

You can take your chances if you want, it’s all up to you :slight_smile: .

I can only respond with experience.

I have the same power supply in the OP's photo that had been powering an Uno (through the 2.1mm power jack) with a Music Shield and a Wemos D1 Mini (from the Uno 5V pin) for months, often 24/7, (my project is taking forever) and the regulator on the Uno is barely warm.

SteveMann:
I can only respond with experience.

I have the same power supply in the OP's photo that had been powering an Uno (through the 2.1mm power jack) with a Music Shield and a Wemos D1 Mini (from the Uno 5V pin) for months, often 24/7, (my project is taking forever) and the regulator on the Uno is barely warm.

It’s all about the amount of current being taken from the power supply, nothing about experience :wink: .

It is more related to the experience of those of us who answer here to the interminable dribble of posts asking "Why when I added this piece to my Arduino did it suddenly stop working after so-and-so length of time". :cold_sweat:

I would also opine that Paul__B's assessment of the on-board regulator is excessively pessimistic, but the basic point is there - the regulator can't provide all that much current. Couple hundred mA is all it can be relied upon for. For anything more than that, you need an external 5v supply.

12 V to an Arduino can be a bit high and the onboard regulator may end up hot.

abraham5:
12 V to an Arduino can be a bit high and the onboard regulator may end up hot.

As stated before, I am powering an Uno with the same wall-wart as the OP. The Uno 5V pin is powering a Wemos D1 Mini. And there is an audio shield on the Uno. It's been running almost 27/7 for three months and the chips on the Uno are barely warm.

Using an IR thermometer, the Atmel processor is the hottest chip on the Uno, at 87.5°(F). The regulator is slightly cooler at 87.2°(f). The ambient temperature in the room is about 79°(F), so statements to the contrary above don't appear to present in my project.