Looking at the schematics for the Minima Transceiver, I notice that there are some inductors included in the top left corner of the schematic, and that the photos on the author’s page appear to show home wound inductors on a toroidal core.
This post is my notes on how to calculate the amount of wire needed and wind those components.
First, I found this post (How to Wind Your Own Toroidal Audio Inductors) by Oren Leavitt showing a useful technique for using a “shuttle” to hold the winding wire while making the wire wraps on the core.
A quick demo video showing a winding being done:
I also need to know how many windings are needed on a core.
The ARRL website has this handy PDF on winding air-core inductors, which includes the calculations for that type of inductor, but since I want to use a ferrite toroid, this is not the math I need.
So let’s see what else is out there…
Here’s a calculator that can calculate inductance per turn:
The above calculator needs the relative permeability of the material the core is made of. I found this handy table of magnetic permeability by medium over on Engineering Toolbox.com which will help with the calculation.
Here’s an alternate calculator that works on specific cores by part number and material: