conecting a oscilloscope to the shunt in a dc 3v motor circuit gives me to much noise in the graph, any idea in proper filter to use?

I need to check the diference in force between the two parts of a non simetrical pulley and that is the way i feel easier to take the time, rpm, position, etc.

In the same circuit I took a photocell to check through the B channel on the osciloscope the positions of the pulley and that is working perfect.

Thanks for advice,

Luis.

 

I would first add a .1 uF cap across motor; still to much hash?, add an RC filtar across " shunt", something like 1k ohm & 1.uF, measure across the .1uF.

 

Yep, you basically need a low-pass filter.
But if the values of R and C are too large, it'll have a heck of a phase shift.

This may very well be too much:

but it's the general idea.
Reducing R1 and C3 will reduce the shift.