Quick question about powering 2 arduinos

So I just wanted to ask this just to be sure I wouldn't burn anything out:

I have 2 arduinos, one a master and the other acting as a slave.
One only has 2 small led matrices, and the other just some pots and buttons.

I have a power supply that can give enough current to drive both of these arduinos, and it will plug into one of the barrel jacks.

Can I connect the Vin pins of both arduinos and connect the grounds to power both through one power source plugged into one of the power jacks?
I'm pretty sure this will work, but my real question is whether the diode between the barrel jack and the Vin pin can source enough current to drive an arduino?

Can I connect the Vin pins of both arduinos and connect the grounds to power both through one power source plugged into one of the power jacks?
Yes you can
I'm pretty sure this will work, but my real question is whether the diode between the barrel jack and the Vin pin can source enough current to drive an arduino?

As long as the total current draw of both boards and their external components is less then 1 amp (typical diode max current rating) and the power module is rated at 1 amp or more, you should be fine. You also could replace the diode in the first board to say a 3 amp diode if your total current consumption is more then one amp.

Lefty

I think I will be powering the board with the LEDs directly from the power source (which can give > 1a) since the LEDs would probably be the most current needy.
As I said, the second board will only be pots and buttons and maybe a couple LEDs, which I’m assuming can be driven with <1A.

As I said, the second board will only be pots and buttons and maybe a couple LEDs, which I’m assuming can be driven with <1A

Should be fine, sounds like that second board will only consume less then 100ma.

Lefty

Okay, so what is the voltage drop on the diode?
I actually have a few power source options of different voltages, would 6v work?
I looked online and it pointed towards saying that 6v can be problematic with the duemilanove. So I think I may just get a low voltage drop 5v regulator, then connect it directly to 5v and gnd pins, right?

And sorry for not being specific about which arduino. Right now both are duemilanoves, but the second one will eventually be replaced by a RBBB or similar custom board.

The docs for the duemilanove specify at least 7V for the power connector. I've found a 5V regulated supply works (no guarantee), ditto 12V.

IMHO you plug a 7-12V supply into the powerjack of your master board, and then simply link the GND and 5V pins between the two boards. When you look at the circuit diagram http://arduino.cc/en/uploads/Main/arduino-duemilanove-schematic.pdf you see that there are no additional diodes taking any drop.

The only potential problem is whether the one MC33269 regulator can drive it, but from your description we seem safe enough.

I was going to use the LM2940, according to the modern device site, it can be used with the RBBB arduino board, with only a 0.5 volt drop.
Could one of these power a duemilanove?

Or, as Msquare said:

and then simply link the GND and 5V pins between the two boards

Would this work?

I have some wall-warts that would work, but I wanted to use a 6v rechargeable battery I have, which is why I wanted to build my own regulator.

Any advice on whether the connecting the 5v's and gnds idea would work?

P.S. I'm not really from Nowhere, Fort Cobb, OK. (first place by that name on google maps)

Quote:
Any advice on whether the connecting the 5v's and gnds idea would work?

Given a reliable source to begin with, sure. But that is really a separate question..

Wel, it is not entirely separate. I just want to power both boards from one source, and I didn't think that that option would work, so I asked about the option I thought of in the OP. Had I known that it was possible, I would have asked about it too.
One of the two arduinos will definitely be a duemilanove, is that a reliable enough source, while powered from the dc power jack?

Okay, thanks for the help.