How can I connect the Tamiya double gearbox to Arduino Uno? I'm working on building my first robot. this is my first foray into DIY electronics. I already have an Arduino Uno, and I have ordered the Tamiya double gearbox here. My goal is to control the gearbox to move the robot, but from what I've already read, I need to have something between the Ardiuno and the motors. It seems like people have trouble doing that because the included motors are low voltage, so the Arduino motor shield won't easily work.  

I'm looking for a clear solution to making this thing run, in the simplest way possible. One thing I'm considering is replacing the motors in the gearbox with these motors. If I do that, am I right in thinking I could run them from the Arduino motor shield? 

If there is a simpler (or cheaper!) way of making it work than being stuck on the Arduino Motor shield, I'm game for that. I've just gravitated to that solution because it seems simpler as an electronics noob. (I haven't bought that shield yet.) But I'm really open to other solutions, so if you can, I'd appreciate the advice!
Here's what I've found about both the motor shield and the motors:


Motors are 3-6V and will use a lot of amperage. This may be a problem with a mobile robot. You'll have to figure out a power source that can provide 4+ amps... on battery power that's a lot. Personally, I would go with a continuous rotation servo for a compact, light robot.
Motor sheild can provide 2x 2A channels at 5-12 V (Source) using the two + and - terminals on the bottom left side of the shield. You must connect external power, because USB can't provide enough power. I can't find if the motor shield will limit current if it goes over, but if you do use the gearbox, I'd recommend another route for control that's 1/6rd the price.


This chip was recommended by Pololu on the product page.



Time to whip out your soldering iron! Really, soldering is a great investment and you'll get to a point soon where you'll need one; there will be no other alternative. Luck for you, you only have to solder 16 joints. Headers are included.

Diagrams from Pololu's site:


  
  
  
  
  
  *(Click to enlarge ^^^)**


*I added a little text to this image.