[rswsmay]

First of all, read the above noted documents posted by Katie.

Now... you need to make sure that you are not trying to control any of the CIM, FP, Globe or the Taigene motors using the spike relays. The are not designed to handle the current draw.

Second, if you are looking to turn on/off (at full speed) the Mabuchi motor, then you could utilize a relay. If however you are trying to vary the speed of the motor, you have to use a speed controller.