I'm wanting to know what wallwart to buy for powering the arduino board together with a 12v dc motor http://tinyurl.com/37w67t.
Things are working (arduino and motor, and simple h-bridge circuit) with a 12v 500ma regulated supply
We've been recommended a 12v 2.1 amp supply. Will this fry the arduino board or cause more problems? Ideally we want to use one power supply for the motor and the arduino, what's the best setup?
I'm also thinking of buying a walwart that has these specifications:
Supply voltage 240V AC 50Hz
Output voltage 1.5V, 3V, 4.5V, 6V, 9V or 12V DC
Output 1200mA (800mA continuous)
Load regulation 1.5% max.
Ripple 10mV
Does the extra current make the motor go faster or is it going to damage something (the arduino or the motor?
The current rating of a voltage regulated power supply is just the maximum it can supply. A 200 amp supply would be just fine, overkill, expensive, and heavy... but just fine.
A word on wallwarts... These typically have awful voltage regulation. They will go well above the labeled voltage when nearly idle and will ripple mightily as the load goes up. Fortunately your Arduino has its own regulator and some capacitors, but if you find "strange" things like your Arduino reboots when you grab the shaft of the running motor that is a clue that your power supply is not up to the job. If you find a wart labeled as a "switching" supply it will generally be much better regulated. These are becoming more common.
And a word on exceeding the current limit... Cheap warts don't have fuses. When you exceed the current limit a filament in the transformer will melt and then you need a new wart. A perfect time to buy a nice switcher, and maybe an inline fuse of slightly less than the rated current of the power supply.