Step 3: Electronics
Any analog Sharp IR distance sensor will do, but I used the long range one because it was more convenient for the firefighting competition. If your robot is smaller, you can use one with shorter range. However, you should consider the dead zone of the distance sensors when picking and mounting them. Try to keep about half the dead zone inside the robot frame, since it will allow you more range. However, if it runs into a wall, it might not recover. Once again, feel free to experiment.
In the picture there are a few resistors which I did not include in the parts list or schematic, because they do not add functionality.
Also, in the schematic, it doesn't show how to wire the IR sensor sensor. There are 3 wires on it. The red wire (power) goes to the 5V after the regulator., the yellow (signal) wire goes to the input of the Op amp buffer, and the black wire (ground) goes to ground.
There is also a 1000uF cap across the 5V supply.
Finally, the servo motors are powered by the unregulated voltage straight from the battery. If you are using different servos and a different battery, you may have to power them from the 5V supply if they are not rated for the voltage your battery provides. Regular servo wires have different colors then Vex servo wires, so it is up to you to wire them.