I was woken up at about 2:30 tonight by something similar to this -, but unfortunately much louder. At first I thought it could of been my near-dead 20 year old ceilling fan, or perhaps a cricket that found it's way in. After looking around a bit, I discovered that the charger of my LG V20 was the culprit. I tested the charger out in a different outlet to see what would happen, but it was the same thing. Anyone know what's up?