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+---
+title: "The KiCoil Planar Coil Generator"
+date: 2025-12-31T13:15:39+02:00
+summary: >
+    I wrote a layout tool generating planar coils that can handle spiral coils, toroidal coils, and hybrids in between
+    the two.
+---
+
+.. raw:: html
+
+    <figure data-pagefind-ignore>
+        <img src="header.png" style="max-width: 20em">
+    </figure>
+
+A planar coil is a coil that is made from flat traces in some printing process like PCB or IC manufacturing, instead of
+being wound from wire. A few weeks ago, I needed one such planar coil that 
+
+
+Project State
+-------------
+
+Currently, circular coils are special cased. Their layouts are directly generated, without the use of polygon
+offsetting. Windings are efficiently approximated using circular arcs. The circular coil layout code is solid, and
+contains decent (albeit not infallible) parameter sanity checks. Its main limitation is that sometimes, clearances can
+be violated a bit.
+
+The arbitrary shape code path is less stable, and produces faulty output in some cases. The most common error is
+crossing traces near the first vertex of the polygon when the polygon has highly convex or concave parts. I'm still
+improving this code path, but as long as you check the output, any errors it produces should be easy to fix by hand.
+
+If you would like to contribute, I'd welcome any ideas on the arbitrary shape code path. I think there is no single
+optimal solution here, and a generic algorithm that can be adjusted to favor for instance shape accuracy versus winding
+smoothness would be nice.
+
+All project links are listed on `https://jaseg.de/projects/kicoil/ <https://jaseg.de/projects/kicoil/>`__. You can check
+out the code on my git at `https://git.jaseg.de/kicoil.git <https://git.jaseg.de/kicoil.git>`__. Issues are tracked on
+codeberg at `https://codeberg.org/jaseg/kicoil <https://codeberg.org/jaseg/kicoil>`__. The kicad addon can be installed
+from the KiCad plugin manager, and you can install the standalone kicoil python package `from PyPI
+<https://pypi.org/project/kicoil/>`__.
+