Design Consideration_RC_Filter
Looking at the Heatermeter project, they reported much improved temperature measurement results and stability when they employed an RC filter in a project version update.
An RC filter is a simple low-pass filter that removes high frequency noise. In the case of the cloudSmoker project, the most likely source of high frequency noise would be mains hum (~50 Hz) picked up by the long temperature probe wires. Given barbecue temperature change and measurements is a slow process, I felt safe trying to design a filter to remove higher frequency noise above 10 Hz.
Okawa Electric Design has a pretty neat online filter RC design tool. Using a 100k ohm resistor and a 0.1 uF capacitor resulted in the following low pass filter which had a cutoff frequency of ~16 Hz. Perfect!
I used some polyester film capacitors and a couple of resistors that I had lying around and placed the RC filter components directly adjacent to the ADC input measurement pins.
