But if you’ve ever built one, you know how tedious winding the secondary coil is. So [Krux] decided to build a machine to do it ... a lot of thought into the design — He’s even got a ...

Anyone who has ever wound a toroidal coil by hand can tell you that it ... That obviously requires a winding ring that can be opened up to allow the toroid form to be inserted; [Sandeep] chose ...