How to wire something that draws a lot of current to the Arduino

I can't belive I'm asking this, but; can I supply the Arduino with an external adapter of say 1 ampere, and then connect something to the Arduino that draws 1A, or do I need to wire a separate power supply to that device only, and then share grounds?
:blush:

Separate!

You can use the same supply but don't supply power from the Arduino, supply it directly from the power supply. And do connect the grounds.

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The Rugged Motor Driver: two H-bridges, more power than an L298, fully protected

Thank you RC!