A black 3D printed machine sits on a workbench. A coil of copper wire is suspended from one side of it, and a screen on the front of it reads "Homing".

Automatic Coil Winder Takes The Tedium Out Of Actuators

October 23, 2026 by Aaron Beckendorf 4 Comments

Anyone who’s ever built their own motors knows how tedious winding the coils soon becomes; in [Larry]’s case, the issue was even worse. He’s building his own flip-dot matrix display, and each dot uses two electromagnetic coils to flip a magnet in the dot. Rather than wind each of these by hand, therefore, he built his own coil-winding machine.

The coil winder uses two stepper motors: one to wind wire onto the bobbin, and one to move the wire guide carriage back and forth, distributing the wire evenly across the bobbin. The bobbin is held in place by a retainer, which doubles as a tie point for the end of the wire. The spool of wire rotates on a pair of bearings, and the wire is fed between two pieces of foam to provide adjustable tension. The housing is mostly 3D-printed, with some metal rods, bearings, and belt drives fleshing out the structure. On the electronics side, a Teensy controls the winder, with an OLED display and a rotary encoder for control. Before beginning on a coil, it homes the guide carriage against an end-stop switch, then winds on layers, keeping track of the number of layers applied.

We’ve seen a few coil winders here in the past, including a 3D printer adapted to winding stators. For more on this winder’s application, check out [Larry]’s flip-dot design.

Playing Music On A Custom Flyback Transformer

February 11, 2023 by Tom Nardi 7 Comments

We’ve seen a number of people create plasma speakers over the years here at Hackaday, so at first blush, the latest Plasma Channel video from [Jay Bowles] might seem like more of the same. Even his overview of the assembly of the 555 timer circuit at the heart of the setup, as detailed as it may be, is something we’ve seen before.

But the back half of the video, where [Jay] talks about the flyback transformer used in this plasma speaker, really got our attention. You see, frustrated by the limited options on the market for AC flybacks, he set out to put together a custom transformer utilizing a 3D printed secondary former of his own design.

Winding an early version of the secondary with a drill.

Armed with a spare core, [Jay] spent some time in CAD coming up with his secondary. Despite never having built a flyback before, his first attempt managed to produce some impressive sparks — that is, until it arced through the printed plastic and released the critical Magic Smoke. Inspired by this early success, he went back to the digital drawing board and cranked his way through several different iterations until he came up with one that didn’t self-destruct.

Continue reading “Playing Music On A Custom Flyback Transformer” →

Tips For Winding Durable Coils With Nice, Flat Sides

June 19, 2022 by Donald Papp 14 Comments

[Drew Pilcher] needed durable, custom-wound coils with no core, and perfectly flat sides. Coils can be wound by hand, of course, but reliably creating perfect coils with thin wire and lots of layers requires some additional help. Happily, [Drew] shares his method for doing exactly that. Perhaps coming as no surprise, the key to repeatable, high-quality coils is good preparation and tools.

The most important part is the ability to rotate a spool for winding without having to take one’s hands off the workpiece. To accomplish this, a cheap, no-name power drill and foot pedal (made from the harvested trigger unit of the drill) forms the basis of [Drew]’s DIY winder. To make coils with precision, one must also count the number of turns. Thankfully, there is a simple solution for this; [Drew] used a cheap digital turn counter from Amazon. This economical device uses a magnet and sensor, so [Drew] simply stuck the magnet on the side of the drill’s chuck.

Careful winding and a liberal application of CA glue helps ensure good results.

The spool is what the wire gets wound around to form the coil, and it will need to be removed from the coil afterwards. To accomplish this, [Drew] uses a brass shaft, metal washers, and some plastic spacers. A light coating of grease on the spool surfaces helps ensure things come apart properly in the end.

To actually make the coil, [Drew] recommends some means of magnification, and a supply of CA glue. Wind the wire as cleanly and closely as possible, and apply CA glue during the process to secure things. It takes some practice, but really clean windings are possible if done correctly.

For thick coils with a lot of layers, the CA glue will hold things together well enough, but for smaller coils [Drew] likes to give them a final coating of two-part epoxy. After things are completely set, the spool is disassembled and the inner core is pushed out as gently as possible.

The result? A tightly-wound, durable coil with perfectly flat sides. It’s exactly the thing [Drew] needs for his upcoming coil gun project. How’s that work, you wonder? You can see the basics covered right here.