Thanks for the reply. I saw those specs too, but that is not enough information. If you look at the picture, the motor has 4 leads. Two of the leads are red and black(I am assuming that these are the power and ground connections) and two of the leads are green and yellow. I need to know which of these leads is for the signal generated by the tach? Are both of them signal leads? Are the power and ground leads common to both the motor and the tach? Also I need to know what kind of a pulse is generated by the tach, a sine wave, a square wave? Is the signal conditioned with an internal Schmitt trigger?