YouTuber [RimstarOrg], AKA Hackaday’s own [Steven Dufresne], shows how to make a DIY inductor for a specific inductance. This is obviously a great skill to learn as sometimes your design may call for a very accurate inductance that may be otherwise hard to find.
Making your own inductor may seem daunting. You will have to answer a few questions such as: “what type of core will I use?”, “how many turns does my coil need?”, or “how do I calculate these parameters to create the specific inductance I desire?”. [RimstarOrg] goes through all of this, and even has a handy inductance calculator on his website to make it easier for you. He also provides all the formulae needed to calculate the inductance in the video below.
Using a DIY AM Radio receiver, he demonstrates in a visual way how to tune an AM Radio with a wiper on his home-built coil. Changing the inductance with a wiper changes the frequency of the radio: this is a variable inductor,
This video is great for understanding the foundations of inductors. While you may just go to a supplier and buy yours, it’s always great to know how to build your own when you can’t find a supplier, or just can’t wait.