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How to Wind an E Core Transformer

Transformers are used to isolate DC power from one side of a circuit, or to increase or decrease AC voltage while maintaining the same signal power. Many transformers are assembled to conform to standard voltage and current values; however, some hobbyists choose to create their own transformers to suit the needs of their custom-assembled circuits. One common transformer type is the E core transformer. As its name implies, an E core transformer has its primary and secondary windings wrapped around a metal core that is shaped like a capital "E." This design allows the transformer to minimize losses while preserving signal fidelity.

Things You'll Need

Transformer E core
Transformer shell
Magnet wire
Non-conductive wax paper
Emery board or sandpaper
Soldering iron
Electronic solder
Solder-type ring terminals
Permanent marker
Screwdriver

Instructions

- 1
  Cut two pieces of wire at least 48 inches long. Sand down the tips of each wire segment until there is at least 1/ 2 inch of bare wire.
- 2
  Place a ring terminal over one end of the first wire and solder the terminal to the wire. Place a ring terminal over the free end of the first wire and solder the wire to the terminal. Repeat this step for the second wire.
- 3
  Place a piece of wax paper around the center leg of the E core. Carefully wind the first wire tightly around the wax paper so the wire holds the paper snugly against the core. Leave two inches of slack at each end of the wire and place the wire ends on one side of the core. Poke two holes through a second piece of wax paper and place the ring terminals from this wire through the holes. Wrap this piece of wax paper completely around the outside of the wound wire.
- 4
  Wind the second wire carefully around the wax paper so that the wire holds the wax paper snugly in place. Leave two inches of slack at the end of this wire and place the wire ends on the opposite side of the core from the first wire's leads. Mark the second wire's ring terminals with an "S."
- 5
  Place the transformer shell over the transformer core and line up the screw holes. Insert the screws included with the shell into the holes through the holes and tighten the screws to close the transformer up.
- 6
  Connect the unmarked ring terminals to the AC input device -- such as a power supply or audio source. Connect the terminals marked with an "S" to the output device -- such as a speaker or other electrical load.

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