Handmade toroidal inductor for "Joule Thief" circuit.

Handmade toroidal inductor for "Joule Thief" circuit.

To make one of these, you need to start with a toroid, which is a piece of ferrite (Iron) shaped like a doughnut. You will also need wire. I used 0.3mm coated copper wire.

Where can you find a toroid?

You can find them in TV’s, computer monitors, and radios.  Another source, and where I found mine, is in a spent CFL or Compact Flourescent Lamp.


I have an Aerogarden brand hydroponic system and the grow bulbs burn up after about 8 months of use.  These lamps have some electronics inside that are useful, including the toroid shown in the video below.  In the video, I also show how I wound my own toroidal inductor.

If you aren’t able to salvage a toroid from scrap, then you might want to shop online, like at surplussales.com.

How can you make your own toroidal inductor? I show how I made mine in a video…

VIDEO:  Handmade Toroidal Inductor


You should take care not to break the tube itself as it has toxic Mercury inside.  What should you do with the rest of the toxic scraps from the CFL?

Recycle CFL’s in the United States

The EPA has a list of retailers that will accept your CFL’s for recycling, including:  Ace, Home Depot, IKEA, Lowe’s, Orchard’s Supply.  See the list of locations at EPA.gov.

Lowes’ website says they have… “installed recycling centers in nearly 1,700 U.S. stores to help customers recycle rechargeable batteries, cell phones, compact fluorescent light bulbs and plastic shopping bags.”  [ Source ]

Home Depot, claiming to be the largest retailer of light bulbs in the United States, offers a recycling center in all of their stores for CFLs.  [ Home Depot PDF describing their recycling program. ]

Another place to search for recycling centers near you:  earth911.com Using this website, I found that Best Buy accepts electronics for recycling, too.

Related Post

See this handmade toroidal inductor working in a circuit…

Related Post:  Joule Thief from Scrap Parts


  1. Watson says:

    I was surprised to find that Ferrite cores don’t have any iron in them. They have nickle, manganese and zinc among other things. Powdered Iron cores do, though. You gave a link to my watsonseblog, which is gone, no thanks to blogger. You can replace it with the one I gave in the website field above. Thanks.

  2. Earl says:

    Greeting. Your updated URL is now here in the comment section.

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