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How to Make a Wire-Wound Copper Resistor

Resistors can control the flow of electricity in a circuit. Copper wire is a good conductor of electricity, but it also has a natural resistance to current flow. This natural resistance makes it good material to use to create small, homemade resistors. To make a wire-wound copper resistor, use wire that has a large gauge. This is because a large gauge indicates a thin wire. The longer and thinner a wire is, the more resistance it has. Wrap several feet of it around an object made from insulating material, such as plastic. Insulators are materials that resist the flow of electricity.

Things You'll Need

Insulated solid copper wire
Cardboard, plastic, or wood
Wire cutter
Epoxy
Electrical tape
Solder
Soldering iron
Digital multimeter
Circuit

Instructions

- 1
  Determine the amount of resistance you need. The value must be small, such as 0.1, 1.0 or 10 ohms.
- 2
  Select a gauge size and use a table to find its resistance per 1,000 feet. For example, at room temperature, 20-gauge copper has 10.4 ohms of resistance per 1,000 feet. Gauge is also represented by American wire gauge (AWG).
- 3
  Calculate the amount of copper wire needed. For example, suppose a 10.0-ohm resistor is to be created. If the wire is 30-gauge, its resistance is 105 ohms per 1,000 feet or 0.105 ohms per foot. A minimum of 100 feet is needed to get 10 ohms, since 100 * 0.105 = 10.5 ohms. Use two to three times this amount, to get 200 to 300 feet. Add an additional 2 inches to 5 inches to this, to serve as leads or lead holders.
- 4
  Use a wire cutter to cut the required length of wire needed. Create or obtain a round or tubular holder from plastic, cardboard or wood. Afterward, construct the resistor by wrapping the wire around the holder. If necessary, use epoxy or electrical tape, to prevent the wire from unwrapping.
- 5
  Strip the insulation from the resistor̵7;s ends. Use the bare parts as leads, or solder 1 inch of bare copper wire onto each end. Place the resistor into a test circuit with a battery and a large resistor. Use a digital multimeter to measure the resistance across the wire wound.
- 6
  Check to make sure the resistor does not become too heated when it is inside the circuit. If it gets so hot that the insulation melts, use a longer or thicker wire, or both.

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