Reverse voltage protection

I mislabelled the batteries in my robot chassis, put the batteries in the wrong way, and loud pop! resulted 😞. The capacitor on the motor driver board had exploded. It's all soldered together, so the easiest thing to do was build another board.

I've done that, and added reverse voltage protection using a mosfet:

Wish I'd thought of that before.

Anyway, I've built another shield to replace the destroyed one.

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