VIN to power servos

[amacmullen14]

Quick question, just for clarification:

The webpage for the arduino duemilanove says

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.

So can I connect a 12v 2000ma wall wart to the arduino power jack, then connect a voltage regulating circuit to the Vin pin and gnd to power 8 servos?  (I've already checked, 2000 ma is more than enough.  They are very small servos.)

I just want to make sure. I don't want to fry anything!   :-?

[keeper63]

According the schematic here (assuming it is the same as your board; you might want to verify this):

http://arduino.cc/en/uploads/Main/arduino-duemilanove-schematic.pdf

VIN comes right after D1, which is connected straight to the jack. Seems like it should work without any problems (provided D1 is robust enough?). There would also be a question of whether the traces and/or the header can handle the current (most likely "yes" - but it is something to consider).

If you are still in doubt, set up your own power system prior to the Arduino entirely, and branch off that to run the Arduino and the servos.

[mowcius]

You should have no issues doing that.

The vin is connected directly to the DC jack so as cr0sh said, as long as the current does not get too much for the width of the track (which is rather more than what you're talking about I would have thought) then it'll be fine.

Mowcius

[amacmullen14]

Thanks for the help, I'm working on a very small 7 DOF robotic arm made from some 5g servos.  (admittedly just because I found them for < $3.50 each)
I was planning on branching the arduino off of the power system, like Crosh suggested, until I found out about that info about the Vin pin, so I thought that might be simpler.

[retrolefty]

Well unless someone can confirm the current rating for the D1 series polarity protection diode use with external power, I would not count on being able to safely pass 2 amps of current out the Vin pin. On my Arduino clone board the D1 diode is a 1N4004 type which carries a 1 amp continous rating.

Lefty

[mowcius]

Well unless someone can confirm the current rating for the D1 series polarity protection diode use with external power, I would not count on being able to safely pass 2 amps of current out the Vin pin. On my Arduino clone board the D1 diode is a 1N4004 type which carries a 1 amp continous rating.

Oh... hmm

You are right. I had got into my head that the diode was after the vin pin. I would have thought it would be safer to have the vin pin protected as well as the DC jack rather than having some external device/supply protected that might be plugged into the vin supply...

[size=10](part way down the left hand side)[/size]

I'm working on a very small 7 DOF robotic arm made from some 5g servos.

Maybe you would be better off with some custom board or smaller board like a pro mini for this project.

I think the final verdict is that it would not be a good idea to connect them to vin.  

Mowcius

[amacmullen14]

Okay thanks again.
No matter what, I was still going to be making a custom board, for a simple voltage regulating circuit, and I had been planning on connecting that directly to the power source, so I guess I will do that.

I just brought up the vin possibility since it would slightly simplify it, even just a little bit.