Battery Questions...

Hello. Can I run my Arduino Uno off of 12 Volts DC? And if I can, how?

Put the 12V in the DC input jack.
If you are running other stuff as well off the 5v line the regulator might get hot and need a bit of an extra heat sink.

Ok. I've seen people plug a battery pack strait into the controller. Does that have to be 5 volts, or is it a different power level?

Ah Vin.

So how would you add an extra heatsink? Anything special I would need to use? I mean, I don't want to damage my board.

What controller?

Heatsink - something that would help dissipate the heat from the regulator without shorting anything in the area.

Maybe a version of something like this

Ideally you would have a switching regulator to take the 12V down to 5V and connect it to the 5V header pin.

I know what a heatsink is, and I said Uno above.

Yeah that one might work. And I only would like to use one powersource, which is 12 volts to run everything. Most stuff I have hooked up to my Arduino is 12 volts, but the RFID Reader is 5v-16v. Barely getting by with that. So that's why I would like 12 volts to also power the relays and other stuff.

If the "other stuff" is 12V, that power wouldn't be going thru the arduino, so the regulator should be okay unless you start driving lots of LEDs or something that will also need 5V.

How are the relays turned on/off? Are those 5V parts, or do have transistors/ULN2003/etc to drive them?

When you said controller, I thought you might have meant a motor controller or something, was just a little funny seeing the arduino referred to as a controller.

Whatever you do for the heatsink, be careful not to short anything.

That's what I'm wondering. How and where do I add the heatsink. And I'm driving the relays with 2n2222 transisters. And I'm using an Altronix 12 volts power source, so I think I'm good there. I'd be running the relays and RFID Reader off of it.

How and where do I add the heatsink.

Glue it on the top of the regulator.

Any spesific type of glue? Or just hot glue? And is the regulator the transister looking thing between the power jack and the usb hub?

The regulator is so small!
Maybe something like this then

The regulator is right next to the power jack.

Search digikey for "thermal adhesive"
Not Silicon Grease tho.

Wow, that stuff is expensive! I'd be tempted to go withthe slip, with some insulating tape on the bottom of the board to avoid shorts.

You have the relays & stuff on a piece of perfboard or something? I would add the regulator there and just bypass the one on board.

Maybe Radioshack has a 12-24 volts > 5 volts or something like that. I'll look on there site. No, I just have regular din rail relays.

Radioshack does! And it's pretty cheap to. RadioShack.com Official Site - America's Technology Store

I should go pick that up and figure out how to wire it. Can I put power strait into 5 volts on the Arduino, or will it reject it? I'd think it wouldn't reject it, but wouldn't be enough @ 1A.

Maybe Radioshack has a 12-24 volts > 5 volts or something

If it is a standard regulator it will still generate the same amount of heat but maybe it will be easier to get rid of. If you go for a switching regulator then there is much less heat.

The 5V DC (!! DC !!) from the RS converter can go right into the 5V pin on the power header, along with ground.
DO NOT GET THEM BACKWARDS! You are bypassing the reverse polarity protection diode. Just be a little careful, double check the connections before powering up.