Does the DC jack on Arduino have a + - preference?

Hello, I have a DC plug that seems odd; I'm wondering if it is safe to use with an Arduino?

As I understand, standard DC plugs have have a negative outside, and a positive inside, as so:
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I have a DC plug that is flipped, so the inside is negative, and the outside is positive. Would that also work with the Arduino jack? It kind of goes against how I understand how DC works, so I'm a bit hesitant on plugging it into Arduino. I'm stripping it, and using bare pins, so it shouldn't matter, but I'm just trying to clarify for the future.

download.jpg

Sorry. No. The Arduino jack mates with the plug as shown in your picture. Reversing the polarity will let the magic smoke out of something on the board.

From the reference section here at the forum:

External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or battery. The adapter can be connected by plugging a 2.1mm center-positive plug into the board's power jack. Leads from a battery can be inserted in the GND and Vin pin headers of the POWER connector.

No, it will not work. Arduino UNO is center positive, as shown in the schematic. In the schematic you will see diode D1 protects the board from reverse polarity, blocking the voltage, rendering the board inoperable.

Actually the picture shows a “plug”, not a jack.

The only reversed version I have ever seen was the charging connection to an electronic dial indicator. As no charger came with it, I had to cut and reverse the wires from the wall wart.

Paul

Got it, thank you guys.

toxicxarrow:
It kind of goes against how I understand how DC works.

The arduino requires a DC power supply having a suitable voltage and sufficient power output capability… and the DC voltage must be applied with the correct ‘polarity’. Making the polarity reversed can or will destroy components of the arduino.

You can always chop the cord and do the switcheroo so your polarity will be good.

Southpark:
The arduino requires a DC power supply having a suitable voltage and sufficient power output capability....... and the DC voltage must be applied with the correct 'polarity'. Making the polarity reversed can or will destroy components of the arduino.

I figured as much; now I have to check polarity of each new plug with a multimeter :/. TY for the info.

Bringamosa:
You can always chop the cord and do the switcheroo so your polarity will be good.

I chopped it up regardless; using it on a Pro Mini; but that's good to know. Thanks.

I figured as much; now I have to check polarity of each new plug with a multimeter :/. TY for the info.

Usually the powersuply will tel you what polarity is used, so no need to grab your multi meter, look for this

Bringamosa:
Usually the powersuply will tel you what polarity is used, so no need to grab your multi meter, look for this

Oh wow, I remember seeing those symbols as a kid on a bunch of different adapters.

Just checked the adapter; sure enough, it has the symbol! Cheers! :slight_smile:

Paul_KD7HB:
Actually the picture shows a "plug", not a jack.

Could perhaps more correctly be called a "line socket" since it is a female connector.

Paul_KD7HB:
The only reversed version I have ever seen was the charging connection to an electronic dial indicator.

Used to be a common trick on Canon equipment, mind you that was a long time ago. Possibly intended to prevent use of other brands of power packs. :astonished:

Southpark:
The Arduino requires a DC power supply having a suitable voltage and sufficient power output capability.

"sufficient power output capability"?

Given the inability of the regulator to supply over 100 mA beyond the 50 mA requirement of the MCU itself, it is most unlikely you will find a power pack with insufficient rating. The problem comes when someone - as so frequently here - imagines they can use the 5 V terminal as some sort of power "output". :roll_eyes:

toxicxarrow:
I chopped it up regardless; using it on a Pro Mini

And that is indeed, best advice for a wrongly wired power plug. :grinning:

Paul__B:
"sufficient power output capability"?

This is/was mentioned as it a golden rule that applies to powering any particular device with a power supply.