5v Wall Wart to Arduino's Vcc and Gnd

Do I need a 5v regulator in between the wall wart and the Arduino's Vcc and Gnd? Thanks!

Don’t use the Vcc input this requires exactly 5V use the Vin as that will use the internal regulator on the board.

Oops, I meant the Vin pin (there's no Vcc on my Diecimila). But it sounds like it will get internally regulated on the Arduino board anyway. Thanks!

Will there be any issue with powering the Arduino from 5 volts? The specs call for a 6+ volt supply...

The Arduino's voltage regulator has a voltage drop, so you have to supply it more than 5 V (specifically at least 6 V, if your spec quote is right) for it to be able to output 5 V.

  • Ben

Unfortunately, I have a 5v supply that I need to power two devices with, the Arduino being one of them. Ben this relates to my dual-supply question from earlier. In that thread (http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1213057755/all-0), user BroHogan told me that he runs an Arduino from 5v all the time without issues. I guess my real questions are, 1. Will the Arduino be damaged at all if it is powered by 5v? and 2. Will it work correctly?

Thanks, and hope I am making at least a little sense :)

He said he's run his Arduino with 5 V connected to his Vcc pin. If you want to power your Arduino with 5 V you will not be able to do it through the on-board regulator (i.e. you cannot power your Arduino by connecting 5 V to Vin). You will instead need to bypass the regulator and connect your 5 V source directly to Vcc. If your Arduino gives you access to its Vcc (5 V) bus, you should be able to connect your wall wart output there.

  • Ben

There is no pin labeled 'Vcc'.

Can I connect the wall wart to the '5v' pin? The Diecimila specs (http://www.arduino.cc/en/Main/ArduinoBoardDiecimila) are kind of ambiguous regarding this:

The power pins are as follows:

  • VIN. The input voltage to the Arduino board when it's using an external power source (as opposed to 5 volts from the USB connection or other regulated power source). You can supply voltage through this pin, or, if supplying voltage via the power jack, access it through this pin.

  • 5V. The regulated power supply used to power the microcontroller and other components on the board. This can come either from VIN via an on-board regulator, or be supplied by USB or another regulated 5V supply.

It sounds like I can, but what do you think? Thanks again!

Yeah, you want to connect your wall wart to the "5V" pin and leave the VIN pin disconnected. I don't actually have an Arduino nor have I ever used one (my experience is with other mega168-based microcontroller boards), so I'm never really sure exactly what is brought out to headers and what the labels are.

  • Ben

It all depends on exactly how much you are getting from your 5V wall wart. Most I have seen are unregulated and produce about 6.5V enough probbly to stop it working. If in doubt then measure it.

My wall wart is from SparkFun Electronics, and information can be found here: http://www.sparkfun.com/commerce/product_info.php?products_id=8269

They state that the adapter is switching-style and regulated to 5v. I have had good experiences buying from Sparkfun so I do not doubt the quality of their products. I will measure it w/ a multimeter just in case, however. Grumpy_Mike, are you saying that more than 5v on the 5v pin will kill it?

The maximum operating voltage of the mega168 is 6.0 V. I’m not sure if the Arduino has any other components with a limit less than this. If your wall wart uses a 5 V switching regulator, then its output is indeed regulated and should be fairly stable at 5 V, which means you can safely connect it to your Arduino’s “5 V” pin.

  • Ben

Great, thanks! I will hopefully receive the wall wart today, and I will let you guys know how everything works out.

OK, just received my wall wart, hooked it up to a multimeter, and I'm getting a steady 5.20 volts. Is that enough to damage the Arduino? Do I need to run the power through a 5v regulator before connecting it to the Arduino?

5.2 V should be fine.

  • Ben