low-pass filter
It is a low-pass filt er. Because the output is being measured across the capacitor, it allows low-frequency signals to pass through easily while shorting high-frequency signals to ground. If the positions of the resistor and capacitor were swapped ( taking the output across the resistor ), it would be a high-pass filter. Low Pass Filters email In hobbyist electronics and practical prototyping (like the Arduino and signal processing projects you are working on), you will generally stick to standard, widely available component values. Here are the most common practical values used for creating low-pass and high-pass filters: Common Resistor ( $R$ ) Values For filtering and timing circuits, resistors typically range between $1\text{ k}\Omega$ and $100\text{ k}\Omega$ . Going below $1\text{ k}\Omega$ (like your current $180\text{ }\Omega$ or $200\text{ }\Omega$ setup) draws more current from your signal source, which can overload microcontroller pins. Going above $1\text{ M}\Ome...