An Arduino IS a Power Supply

Other Hardware General Electronics
1

"An Arduino is NOT a power supply" is a hackneyed nostrum at best.

Contrary to the rubrics - an Arduino IS a power supply.
That's not its primary function. And this facility is definitely limited, modest.
So what?

There are no power supplies, or batteries, of any sort that have NO limitations. Some are capable of more than others.
If a bench-top supply, a lab supply, doesn't have enough juice for the device under test it doesn't stop being a power supply. It's a power supply of insufficient capacity in that case - that's all.

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2

Powering a couple leds with a suitable current limiting resistor and a few low power sensors, from a reasonable Vin or USB power is generally not commented upon.

The quote is mostly used in the forum when OP wants to power motors, relays, GSM boards etc ==> power hungry devices. It's usually a good advice.

That's what I've seen

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3

I've read it, seen it, too many times, as a sweeping and misleading over-generalization.

4

OK - not my experience but it's possible indeed

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5

Same holds for the lm293...

Advice: Throw away immediately!

Imagine some kid got a kit for his birthday...

Why not get it working with the lm293?

Even if it wastes power. It can still bring fun.
And if the project is build for one or two days, what is the purpose of buying a mosfet thingy?
Some people seem to not realize that a 7.50 euro thingy plus 7.50 euro DHL costs are quite significant for a 10 year old...

6

Yes I agree

7

I also agree

8

Well clearly no, an Arduino is in the category "development board" not "power supply". If you go to a website to find Arduinos, do you look under "Power supplies"? Obviously no one lists or recognises it as such.

Also quite clearly, an Arduino contains a power supply, but that is not its primary function. So an Arduino can be used as a power supply within limits (as with any device), but that does not make it a power supply

It would be like saying you could live in a car, therefore a car is a home. Clearly you could (and some people do) live in car, but it is not a home.

A separate question is whether an Arduino should be used a power supply; in 99.9% of cases the power requirements are outside the limits of the Arduino power supply function, and therefore as a generalization "an Arduino is not a power supply" is strictly correct, and is a reasonable starting point for advice in most cases.

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9

Another generalization. Do you have statistics to back up that claim.
What are these limits you mention?

10

Context matters.

I use an Arduino as a power supply often. It can be very handy that way. And when I use it that way I do so within its capability.

11

let's go back to science:

can we agree on a definition ?

suggestion:

A power supply is an electronic device or system that provides electrical energy to an electrical load. It takes input power from a source, such as an electrical outlet or a battery, and converts or regulates it to deliver the appropriate voltage, current, and frequency required by the load. They come in different types, including linear power supplies, switching power supplies, and uninterruptible power supplies (UPS), each designed for specific requirements and applications and, the power supply's delivery capability is crucial, as it determines the maximum amount of electrical power it can provide to the load reliably and efficiently.

with this definition, an Arduino is a power supply, with all its limitations.

if we go back to day to day talks, we tend to take shortcuts and have the context as implicit, esp in forums.

I've seen the quote "An Arduino is NOT a power supply" used in the context where OP wanted to do something crazy with his arduino that would go close to or over the limitations and be a risk. The catch phrase is meant to attract the attention to the very limited capability of the Arduino as power supply in the grand scheme of things.

I've never (or may be very rarely ? I would be keen to see examples where this happened) this being mentioned as an argument when someone was feeding 5V to a small LED for example.

is this worrying you so much?

12

  • I say this to individuals who use the 5v pin on Arduinos to power motors relays and similar.

  • To this statement I usually qualify “okay for light loads only”.
    “Large loads and inductive loads should not be connected”.

  • I have never seen this comment made when an Arduino is only connected to devices like LCDs, RTCs, LEDs . . .

  • I think we can agree “NOT a power supply” is used when users try to take too much current from the 5v pin.
    The statement is used to make the user aware of the potential of damaging their Arduino.

  • Overgeneralization, :thinking: , I don’t believe this is the case as the warning is never said as a stand alone statement, there is always context that goes along with it.

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No not allways.
Rule #1. A Power Supply the Arduino is NOT!

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  • I and others here, have used an output pin as a power supply.
    :scream:

When a user tries to take too much current from the 5V or 3V3 pins, I will continue to use the statement “the Arduino is not a power supply”.

15

me too, for LEDs for example.

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16

I am pretty sure I saw an example yesterday. And that was not the first time.

17

Well I only have one eye.

:wink:

18

The Arduino 5V and 3V outputs are, like everything else in life and electronics, limited.

Basically all I have read is this absolutist "not a power supply" nonsense, probably never as: "in your case, the demands of your project, the 5V output is inadequate."

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19

I could live with this.

:+1:

20

All I see by the use of the "comment" is somebody itching to be a s.a.