Circuit questions - what is the capacitor for?

Getting Started
1

I have four SCT-013-030 - which have a built in burden resistor and give a an output of 0 to 1v.

My question is about this circuit. Since the article doesn’t explain what purpose the components serve

  1. Do I need a voltage divider with my CT clamp? If it only outputs 0-1v, it doesn’t seem like I would need a voltage divider…
  2. What purpose does the capacitor serve?

I’m using an ESP8266 (3.3v logic) and I have a fixed voltage value of 122.1, which is what I measured from my wall outlet.

I did some test readings wiring up the CT directly to the analog input of my arduino and with a calibration value of 49, the emonlib is showing the correct wattage for 60w, 72w, 132w and 750w resistive loads I have put on the circuit.

49 is just a calibration number I narrowed in on by trial and error, but the output results seem to be correct.

2

If you read the article that precedes that one in the series, it is explained.
The way to calculate the correct calibration is also explained in the ‘Learn’ section, in the “Current & Voltage” section.

3

Also see this question in the FAQ section:
Q: I’m trying to calibrate my system with a 60 Watt lamp. Why are my readings wrong?