noise in siganl going to counter

[toomosta]

hi,,
i am using a sensor-ir- in wall following and i need to count the walls i face so i connected the forward sensor to comparator then to counter(74191) but the counter counts more than one pulse -even when i move a paper accurately-,so i need a way to remove these noise
thanks.

 

[BradtheRad]

Typically a comparator's output is either a path to ground (0V), or very high impedance.

And I think your 74191 input needs to see either 0V or Vcc.

This means your comparator does not provide Vcc. The 74191 input is floating to some degree, and is liable to pick up electromagnetic noise.

A pullup resistor is often needed in these situations.