Step 3: Wind the 40cm Coil With 20 Turns and the 20cm Coil With 15 Turns
You’ll first make a few loops with the wire on the outside nail to anchor the wire, then start the loop around the coil. Make sure you leave a lot of extra wire at the beginning and end of the coil. Leave 3 feet to be safe (you’ll need this to hook up to electronics).
It’s surprisingly hard to keep track of the number of windings. Use a friend to help you.
Make the windings REALLY tight. If you end up with loose windings, the coil will be a mess.
It’s really hard to keep the windings in order (especially if you use 18 guage wire, 24 wire gauge is easier to handle but has a lot more loss). So you’ll need a few people to help you hold it down as you wind it.
After you finish the turns, you’ll want to twist the inlet wire & outlet wire to hold the coil steady. Then tape the coil with electrical tape in several spots.
When you’re done with this step you should have two coils, one coil with a 20cm diameter and 15 turns and one coil with a 40cm diameter and 20 turns. The coils should be wound tightly, and secured with tape. You should be able to pick them up and handle them easily without them falling apart or unwinding.