Thank you for your reply!
It's not that I don't know how to do the math but thank you, I don't know the cut off frequency yet, I'll have to find it out,
and that's going to be an experimentation process. I don't even know the order of the filter I am going to use yet.
And it's neither a passive nor an active design, it's going to be a digital filter, that's why I said PC application.
All the data are passed to the PC application and then I am going to build/code a low pass Butterworth.
And probably I'll go for a high order butterworth, I need it to have a very fast response and only smooth out
the switching noise from the electronics.
But thanks for the reply anyhow :-D