How-To Guide: Making an Inductor

Seeing as I’m in the middle of a semester-long project, I thought I’d share something I learned how to do at uni recently. For our garage-door project as part of ELECTENG 209 we have to make our own inductors for the transmitter and receiver. I’ve seen these things inside computers before but I never thought we’d actually have to make our own. Turns out they’re not actually that hard to made. With a few key tips and a bit of know-how, you’ll be on your way to making your very own inductor too!

Instructions for Making an Inductor

Things you’ll need:

- Copper wire (preferably thick-ish) for the inductor
- a cylindrical object like a pen to wrap the wire around
- wire clippers
- electrical tape (optional)

Firstly, cut the required length of copper wire. If you don’t know how much wire you’ll need, it’s better to cut a length longer than you think you’ll need so you can trim it down later. Start winding the copper wire around the cylindrical object by leaving approximately half a finger length at the end and wrapping the copper wire around tightly.

Continue to wrap the wire around, making sure that kinks and gaps are minimised. When you have enough turns in the inductor, leave another half finger length at the end before clipping the wire. Make sure the two ends of the copper wire are facing the same way.

Using the wire clippers, scrape the ends of the copper wire to remove the wire coating. This is important for the next step.

Remove the wire from the cylindrical object and connect the ends of the wire to an inductance measuring machine. The connectors need to make good contact with the copper to give a proper reading, which is why the copper coating needs to be removed beforehand. If the inductance reading is too high, you may need to shorten the copper wire and then repeat steps 3-5 until the right inductance is found.

When the correct inductance is found, use electrical tape and wrap it around the coil of wire to make sure the inductance does not change.

Remeasure the inductance after the electrical tape is applied to make sure the inductance has remained the same

You now have your very own inductor!

Notes:

The choice of the cylindrical object used can have an effect on the inductance. Larger circular area will produce a higher inductance with less wire turns.
Keeping the turns tidy and close will help to give more predictable and reliable inductance readings.
To reduce the inductance slightly, you can loosen the turns by stretching the ends of the windings. Be careful not to stretch them too much though.