Powering an Arduino Mini Light rev 05

Hi,

I'm looking for some guidance on how to correctly power my Arduino Mini Light 05. I'm currently powering it through another Arduino Duemi board using the 5v pin and I would like to know what options I have for powering this device! I'm using the board for a LED lighting project with 12v LEDs. It is possible to use the 12v to power the Arduino Mini? Can I somehow get the voltage down to 9v or 5v? Should I prefer 9v over 5v?

I'm an electronics noob so please keep that in mind when answering!

Thanks a lot

"Operating Voltage 5V"
"Input Voltage 7-9 V"

Looks like you can feed it regulated 5V or unregulated 7 to 9V.

Cool .. thanks John!

So to power my leds I have a regulated 12v supply. Can I somehow attach that to the Arduino as instead of needing to have another 5v power supply? E.g. can I power down the 12v to 5v using a resistor or voltage regulator of some kind?

You can use a 5V linear regulator to get regulated 5V from your 12V supply or you could use a 7V to 9V linear regulator to get 7V to 9V from your 12V supply and then feed that to the onboard regulator.

Resistor voltage dividers don't work for a load heavier than an analog input (very low load) because the load acts as a resistor itself and changes the characteristics of the voltage divider.

Thanks a lot John, awesome! I've been looking around and found these TracoPower DC/DC converters that take up to 32V and convert it to 5V.

US: Mini DC/DC Step-Down (Buck) Converter - 5V @ 1A output [TSR12450] : ID 1065 : $14.95 : Adafruit Industries, Unique & fun DIY electronics and kits
EUR: http://www.conrad.nl/ce/nl/product/156673/DCDC-omzetter-TSR-1-serie-1-A-TracoPower-TSR-1-2450in65-32-VDC-out-5-VDC-1-A-1-A

Those would solve my problem, but I'll also have to mount the components to something which makes me wonder if I shouldn't just go for the Arduino Pro.

It looks like this one can take 12v without problems and the space isn't really an issue for me. When I use a 12v adapter to power my LED's and the Arduino how much current should I reserve for the Arduino Pro? Oh hold on .. I just read this:

http://australianrobotics.com.au/news/fuelling-your-arduino-why-you-should-use-an-external-power-breakout

That post says that even though 12v input is in spec for the Arduino Pro it causes several issues and that you should always try to provide the minimal amount of current to the Arduino. Their solution is a rather expensive power regulation board that I would prefer if it wasn't for the price. Are there any other options like this instead of the DC/DC converters? A separate board is kind of appealing.

The Arduino itself uses about 100 mA. If you are driving a single LED directly from an I/O pin, add 20mA. Similarly you have to account for any other loads on the output pins.

The main problem with feeding 12V (instead of 7V) to the Arduino is that the linear regulator will tend to get hot. The Arduino need 100mA and therefore 100mA will pass through the regulator. The output side of the regulator is 5V. If the input side is 12V that means that the regulator has to turn 7V (12V-5V) at 100 mA into heat. That's 0.7W (7V * 0.1A). If you feed it 7V the regulator only has to dump 0.2W (7V-5V * 0.1A).

Thanks for the info. I have the Traco TSR voltage regulator and I have tested it with my multimeter. It turns the 12vdc into 5vdc effortlessly.
I expected that the Arduino mini would also have a Vin port that bypasses the internal voltage regulator but I discovered that is doesn't have one. Can I simply put the output of the TSR onto the 5v pin of the Arduino mini?

Should I add a capacitor somewhere or perhaps a diode? Or is this project near finish? :smiley:

Fexduino:
I expected that the Arduino mini would also have a Vin port that bypasses the internal voltage regulator but I discovered that is doesn't have one. Can I simply put the output of the TSR onto the 5v pin of the Arduino mini?

On the UNO the "Vin" pin does NOT bypass the regulator. That's the one you would feed 7 to 9 to. For regulated 5V you use the "+5V" pin. I expect it is the same on the Mini.

That regulator can take a higher voltage, up to 16V, but it only outputs 150mA

http://www.digikey.com/product-detail/en/LP2985AIM5-5.0/LP2985AIM5-5.0CT-ND/3701530