I have built my own H-bridge to control motors from my PC. When I thought of starting this project - it would be nice to have a micro controller so the 'brains' can all be onboard. Then I looked at hooking up an H-Bridge IC and an ADC chip up to one of my old Windows Mobile PDA's. But in the end I decided to use a MAKE controller board because it's ready to go and just so cool. Very configurable and designed for hacking, it's perfect for this job.

Lets start with the template. I cut this (DXF) from plywood using a laser cutter - but a coping saw will work just as well.

The 4x2cm rectangles cut into the sideboards accomodate the converted servo motors. These are nicely geared down DC motors with the mechanism for absolute positioning removed. This means they simply turn in one direction for as long as you like, perfect for putting a wheel on!

It just so happens the MAKE controller board H-Bridge and software libraries support polarity and pulse width modulation. In english that means you can go forward, reverse and different speeds!

The servo motor is attached using wood screws and a small section of ply on the other side to hold the screws. A nut and bolt would work equally well.

Next the servo horn is pinned to the plywood wheel. Then the wheel is screwed to the servo using the screw provided in the servo kit.

Come back soon for the next stage where we will be adding some sensors so our robot can go exploring on it's own.