The low-pass filter shown in figure 1 uses two RC networks. Frequencies under the calculated value passes without attenuation. Frequencies above the calculated value are blocked.
Formula 1
Low-pass filter:
f = 1 / (2 x π x R x C)
Where:
f is the frequency in hertz (Hz)
R is the resistance in ohm (Ω)
C is the capacitance in farads (F)
π = 3.1416
R3 = 2 x R