We are doing our final year project named CNC Mini Engraver using MACH 3, software. We are having problem to distinguish the step pin signals as it come between 0.07v and 0.11v. How do we distinguish such a low voltage signal to identify the step pin signals. We tried to use LM741 to amplify it, but the result was not satisfactory and we could not distinguish the step signal signal. The direction pin out put are 5v and 0 v for positive and negative axis.

 

Are you using a voltmeter or an oscilloscope? If a volt meter then it is just that your meter will not be fast enough to see the rise and fall and thus will read the average. The faster you pulse the higher the voltage will be but you will still not see anything like 5v on the step pin. Having said that if you change the active state of the step pin then you will see 5v when stationary and it will drop slightly when moving as it is just the opposite of what I first described.
Hood