Introduction: Magnetic Wire
Magnetic wire is used by hobbyists and engineers for coils, inductors, transformers, and solenoids, and it is not cheap to buy at $25 to $60 dollars a pound. This is the wire I gathered in one weekend for no more cost than my time. The ten pounds of salvaged magnetic wire from 16 AWG to 34 AWG would have cost me about $300.oo dollars to buy new. And that doesn’t include the other salvaged parts like heat sinks, transformers, and other components as well as sellable scrap.
I have a homemade coil winder I use to make my own custom transformers, coils, and solenoids that I use in my projects like this auto loading coil for a coil gun, or my first coil gun where I made the step up transformer as well as the propulsion coil.
As a green project this one saves energy in the making of wire and other components as well as recycling, one of the biggest savings is to your pocket book.
Step 1: Locating the Magnetic Wire
I get most of my magnetic wire from working TVs and Monitors, people are throwing these out because they are upgrading to the new stuff on the market. Or in the case of TV sets upgrading because the transmitters have gone digital and the old analog TVs can’t receive the signal.
The yoke ring coils as indicated in the second photo with the yellow arrows, the yoke ring coils consisting of 28 to 34 AWG wire are in the front and the back of the yoke.
The lacquered yoke coils wrapping the yokes ferrite cores indicated by the red arrow in the second photo are too hard to salvage for reuse as magnetic wire, however they bring as much as $2.50 a pound cleaned copper.
The picture tube coil indicated by the yellow arrow in the third photo, on the back of the picture tube can be wrapped in electrical tape, foil wrap, and shrink tube. The magnetic wire in this coil can be 24 to 34 AWG.
Step 2: Gaging the Magnetic Wire
The yoke ring coils are small enough to store without transferring to a spool so I just measure them and mark them by size and approximate length.
For this you need three things, a 1 inch outside micrometer, a tape measure, and an Insulated and Bare Copper Wire Table. For my tables I use my book, “Electronics Vest Pocket Reference Book, By Harry Tomas.”
This book is a quick reference for color codes, circuit examples, formulas, and tables used by technicians and engineers alike. If you find one of these books don’t lose it I have been offered a hundred times what I paid for mine. The tables have every dimension and property of wires and other basic components you need for electronics.
This yoke coils wire is 0.0115 of an inch in diameter on top of the insulation #34 AWG wire is 0.0106 to 0.0118 of an inch on top of the insulation that makes this wire #34 AWG magnetic wire according to the Insulated and Bare Copper Wire Table.
Then using the dimensions of the coil 0.25 x 0.25 thick bundle divided by the thickness of the wire I get 484 turns on the coil.
Next from the center of the coil bundle I measure the diameter of the coil and get 5.5 inches and multiply that by Pi giving me 17.3 inches in circumference.
Multiply that by the number of turns and you get 8373.2 inches or 697.8 feet.
So I have just less than 700 feet of #34 AWG magnetic wire and I record this on the side of the coil.
Step 3: Cleaning the Picture Tube Coil
Never hurry this, take your time cleaning the picture tube coil.
Start by finding the end of the electrical tape, this is usually near the leads of the coil and take your time exposing the ends of the leads.
Trim off the leads and expose more of the wire.
Then measure the diameter of the wire, this wire is 0.0255 inch in diameter on top of the insulation, #24 AWG is 0.0251 to 0.0268 inch in diameter on top of the insulation that makes this magnetic wire #24 AWG according to the Insulated and Bare Copper Wire Table.
Since I have the loose wire exposed I just count the number of turns coming to 120 turns on the coil.
Now I can measure the outside of the wire coil with the measuring tape and get 62 inches in circumference and multiply that by the number of turns and get a length of wire out in left field. Or I can reshape the coil round measure the diameter of the coil from the center of the bundle coming to 18 inches multiplied by Pi giving me a circumference of 56 inches. Now I multiply that by 120 turns giving me 6786 inches or 565.5 feet.
Now I can mark the coil #24 AWG and 565 feet and place the coil in storage, or I can remove the rest of the electrical tape and transfer the wire to a spool. In my case I like to make the wire easy to store so I remove the tape leaving just a tab of tape keeping the coil from unwinding until I can spool it.
Step 4: Spooling the Picture Tube Magnetic Wire.
I save spools from fishing line, ribbons, wire and other sources just for jobs like this; I start by selecting a spool large enough to hold all the wire I am spooling. Remember the bigger the coil I am salvaging the larger the spool I need. I drape the coil of wire over the back of a chair and starting at the outside end of the wire and taking my time I start winding the wire around the spool until all the wire is on the spool. When that is done I mark the spool with the wire size and length.
Step 5: Epilogue
This is roughly $150.oo of wire I salvaged in 1 evening while I watched TV, but that is not all I salvage. I salvage the transformers, heat sinks, wires, and components from the circuit boards. I have run across power transistors that are $85.oo each new let alone heat sinks that are impossible to find. And that is for components they still make. But most of all it saves these things from ending up in the landfills.