for FB group Electronics Hobbyists
The demonstration of a wireless charging circuit that I built uses a Joule Thief circuit with two yellow LEDs in series. The coil is a hand wound loop about 75 mm or 3 inches diameter. A second loop of gray wire with a white LED (dimly lit at bottom) is used as the pickup coil, which would be in the device to be charged.
I wonder if this can also capture the energy from a nearby transformer as an energy harvesting method to charge a supercap and power a night light, perhaps off of the leakage inductance from a microwave oven transformer.
The transformers are designed to minimize leakage inductance. What I’ve done is connect an earphone to a coil of fine wire and use it to sense the magnetic fields. I got the loudest hum at the wall of a room where a big electrical panel was on the other side of the wall.
The amount of power that that coil captured was enough to hear in the earphone, but I don’t think it was enough to even dimly light a LED.