Lately I pulled out of my bench a coil I wound years ago to attempt a project from PJKelly Ch33. It is wound with 100turns bifilar coil, and on top of that around 190turns of wire(I ran out of room to do a full 208 turns).
The bifilar is ran as a simple joule their, with a 5k resistor at the base. I haven't had a lot of time to completely test the setup, and verify that an actual charge is put on the receiving battery, and I will upload pics and details later.
The first battery I connected was the small one you see in the video, it started with 1.28volts(so I assume it's a bad battery). My PS wouldn't even charge it. After 2 hours it read around 7volts. I charged it all night and it's now up to 10volts, the circuit without a bulb is only consuming about 20ma.
So far the circuit seems promising, though will probably need to make coils wider, and more turns on secondary.
https://www.youtube.com/shorts/yPkBRPizIkM
When I get home I will show waveforms, also some questions I have regarding strange things that happen when a ground is connected.