Robot.................

...meandering.  The HC-SR04 ultrasonic ranging module isn't working at this time - the width of the 'beam' catches the battery pack, but it works in photovore mode (although best in low light levels).  Need to devise a more forward mount for the module.

The 114:1 gear ratio of the Tamiya dual gearbox works fairly well, but already I'm seeing a need for higher voltage motors....something along the lines of the Pololu 130 6-volt units.  They'll drop into the gearbox with no modification.