I want to measure an AC current with a current transformer and an arduino device. I found on a website (http://www.homautomation.org/2013/09/17/current-monitoring-with-non-invasive-sensor-and-arduino/) that measurement circuit:
My question is, why do I need a capacitor here? The explanation from the website is:
The capacitor C1 (10uF) has a low reactance – a few hundred ohms – and provides an alternative path for the alternating current to bypass the resistor.
But why do I need an alternative path for the alternating current?