Little eBay Tesla Coil Gets an Upgrade

Like so many of the projects we feature, this one started with a cheap eBay module purchase. In this case, it was a little Tesla coil that made decent sized arcs but wasn’t quite good enough. The result was a super-sized solid state Tesla coil with better results and room to grow.

As [GreatScott!] discovered, the little eBay Tesla coil has a pretty neat design. The exciter is a Slayer circuit, a super simple one-transistor design. His reverse engineering revealed that the primary coil is simply a loop trace on the PCB under the secondary coil.¬†Sadly, his attempt to replace the primary and reproduce the Slayer exciter resulted in anemic performance. What’s a hacker to do in that case except build a bigger coil? Much bigger — like “build your own winding jig” bigger. Twelve hundred secondary turns and an appropriately menacing-looking primary later, the results were — still anemic. It turns out the Slayer is just not up to the task. He turned to an inverter circuit that was previously used in a wireless energy transfer circuit, and we finally get to see a little of the Tesla coil magic. But wait! There’s more to come, as future videos will tweak the circuit and optimize the coil for¬†better performance.

It’s no surprise that Tesla coils are a popular project around here, especially the musical kinds, from the tiny to the large. Music doesn’t seem to be on [GreatScott!]’s mind, though, and we’ll be watching with interest to see where he takes this build.

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The Automated Pickup Winding Machine

winderBack when electric guitars were a new thing, winding pickups was a very labor intensive and error-prone process. The number of windings could easily vary by a few hundred turns of wire, making the resulting pickup either anemic or much more powerful than the other pickups in the guitar. [Davide] is starting to wind his own pickups, and desiring a little more precision than simply guessing how many winds are on a coil he built an AVR coil winding machine.

The machine uses a DC gear motor running at 1200 RPM. A magnet is glued onto the motor shaft, and a hall effect sensor connected to an ATMega8 keeps track of how many windings are on the coil.

The interface is simple, using character LCD to display a wind counter, motor direction, and current motor speed. There are some useful features in this machine; slow start-up and automatic stop makes winding pickups much easier than the traditional home method of winding pickups with a sewing machine.

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