Arduino Uno Wall Adapter

There is no EXACT answer, they all will do great.

The reason for the diversity is that the arduino is a building block, and has on board regulators for 5V and 3.3V.

- if you read and report temperatures, you project will need very low power

- if you drive stepper motors or servos it will be more demanding.

To confuse you even more - if you just want to get started and flicker some led's and reading switches the usb

computer connection will do. No external powersupply needed in this case. The usb 2.0 provides about 500mA.

Sorry, but the real answer is "it depends".

I have a large box of orphaned powersupplies where i go to find a powersupply for the arduinos.

My criterias:

- the connector has to fit

- no AC supplies, DC output only

- at least 6V, no more than 16V

Like Christer said, you don't need a power adapter - the USB connection to your computer is plenty.

For those rare cases when I needed it to be powered independently from my computer, I've simply used the power adapters for my cell phones to provide power through the USB connection. The iPhone cubes are nice for that, with 1A of power

Cheers,

-Nico

Thanks so much for the reply it really was extremly helpful, i just have one quick follow up question. If i were doing a low power project like reading and reporting tempuratures and i were to use a power supply that provides much more power than is actually needed for said project, would it over heat or be harmful in any way, shape, or form? For example if hypotheticaly speaking my project required 5V but the power supply provided 15V where would the extra 10V go? Would it not be used at all or be converted into heat or something else?  (Also i'm not really sure if Volts is the correct unit of measurement for what i am asking so you can just ignore it if it's wrong)  And again thank you so much for the much needed help.

It is smarter to use a 6V power supply, because just as you suspect, the rest is "regulated" away.

This is more important for more power hungry projects, but for less power hungry projects it doesent really matter.

Lets think like this:

P=U*I

If you have a 1A consuming project using a 6V supply, 1V*1A=1W will be dispatched (wasted) thru the power regulator and 5V*1A=5W will be dispatched thru the rest of your project hardware.

If you put the same project on a 12V power supply, your project will still dispatch 5W, but the power regulator will dispatch (waste) 7W, a 6W difference.

Do the same calculation for a 200mA project and the difference is much less.

In all cases - both energy used by your project hardware and energy regulated away will turn into heat.

Christer

While your theory is sound, some of the regulators require a certain 'overhead' to regulate properly.

This ranges from 2v for normal type down to 0.2v for some lDO (Low DropOut) types.

Generally the voltage should match the voltage the load requires, or is designed to run on.

In the case of 'most' arduinos its 6 to 12v.

Tony

Voltage never goes away. it is the force or 'push'.

I suggest do some searching as there are some good analogies out there, that i don't have room to add here.

Mark

Agreed, but power supplies of the simple type discussed here in my experience always deliver over the nominal marking, at least if you draw conservative amount of power.

A 12V power supply might actually deliver 15V if you put a meter on it to check, and so i expect the 6V to do as well. That give the extra margin 6V(nominal) to 5V regulated i think you found missing from my previous post. The 6V power supplies i have salvaged has worked OK for this in my experience.

The minimum voltage drop needed is easy to find out if you put a power cube as power supply and a meter on the 5V regulated on the arduino. Then decrease Vin until 5V regulated start to drop. There is your absolute minimum Vin.

Christer

Don't get confused with open circuit voltage, and the voltage when the rated load is being drawn.

While the older transformer based supplies might exhibit this, the newer switchmode supplies will be the same voltage.

Your adjustment theory works, however the regulators can get very noisy (electrically), so its not a complete solution.

besides you are talking about 2 volts at a maximum of 500mA which is 1 watt.

Some of the Arduino boards have Low Dropout regulators, but you would need to check the numbering on them to be sure.

Personally I tend to use a 9v power pack if I 'm powering it from the mains.

Mark

So, over all i should buy a couple different wall adapters so that i can switch them out from project to project depending on how much power is required? If that is so than could you all give me the technical limitations i should stay within. (Although you should know I am planning on doing every thing from simple LED's to powering motors, which i presume needs more power)