Filters

Filters are often tied with EMI

Theory

Comparing Low Pass Filters to Voltage Dividers

The usual way to design an analog lowpass filter is to combine a resistor with a capacitor, as shown below:
A standard R-C lowpass filter.

The filter can be thought of as a voltage divider in which R is constant and C begins to conduct better as the sine-wave frequency of the input signal increases.

From:

Links

• https://www.eevblog.com/forum/metrology/0-1-hz-to-10-hz-passive-filter/ - 0.1 - 10hz filter.
• https://www.eevblog.com/forum/metrology/diy-0-1-to-10hz-noise-amplifier/75/ - diy 0.1 - 10hz amplifier. early (incomplete) schematic included. Should be easy to make your own board (but try to throw some money towards the author if you can afford to).