I have been spending some time finding ways to reuse my old Mindstorm sensors for use with the Handy Board. Fred Martin’s book simply instructs you to cut the Lego wires and solder them to a simple header pin assembly. I was uncomfortable with that since I only have a limited number of Lego wires and the short ones would be too short if I cut them in half. I found that there is a steady supply of Mindstorm parts on e-bay, but I found another option.
My RCX died from battery acid that had leaked from batteries that I left in years ago. Since I have the Handy Board, I have no use for the RCX. The RCX has six very specialized electrical bricks. The RCX has two rows of three connectors of these electrical bricks for Lego wires. After taking apart the RCX, I found that all six are easily popped out of the RCX shell. I have hacked these bricks to provide an easy way to preserve my current Lego wires and add additional length for interfacing to the Handy Board.
The brick on the far left is the unchanged brick out of the RCX. The brick is held in place in the RCX by two tabs. I scored the tabs with a knife and easily bent and broke them off. This is shown in the middle brick. I used an old 28 gauge ribbon cable to create a custom cable for the adapter. I soldered the two wires to the metal tabs of the electrical brick. Care should be taken not to apply too much heat or the brick could melt. The results of the soldering are on the right side. Next I bent the metal tabs down and applied electrical tape as shown below.
Now this adapter can be connected to an existing Lego wire without cutting it. I can also extend the length by using a different length of ribbon cable.
This is how the robot from chapter one looks with the sensor adapters installed.