How to Make a Simple Rheostat


A rheostat is another name for a variable resistor. This simple component drops a certain amount of voltage in a circuit, which is proportional to the adjusted position. It is often used in dimmer switches for chandeliers, model train control packs and volume adjusters on stereos, to name a few. A simple version of a rheostat is also used frequently for school science fair projects and in the classroom for the purpose of illustrating variable resistance.

Things You'll Need

  • Oxidized door spring
  • 18 AWG solid wire
  • 3 alligator clip test leads
  • Wire cutter
  • Wire stripper
  • Piece of scrap lumber longer than door spring
  • Staple gun with staples
  • 9-volt battery
  • Hobby light bulb in socket
  • Mount the spring to the piece of scrap lumber. Keeping the spring coils together, hold it to the board with one hand and using the other hand, staple each end of the spring. One staple for each end should be sufficient.

  • Create the wiper wire. Cut about a 3-inch piece of wire with the wire cutter. Using the wire stripper, remove about 1 inch of the insulation jacket on either end.

  • Connect a test circuit. Clip one end of an alligator clip test lead between the positive terminal of the 9-volt battery and the other end to one end of the spring, which now serves as the rheostat coil. Another test lead should connect between one end of the wiper and one connector on the hobby bulb socket. A third test lead should connect between the other hobby bulb socket and the negative terminal to the battery.

  • Test the rheostat. Holding the insulated part of the wiper you made in Step 2, touch the free end of it to the coil and vary its position. Notice how the brightness of the bulb varies based on the position of the wiper distance from the direct connection between the battery and coil.

Tips & Warnings

  • The spring must be oxidized, because a shiny metal spring will not resist current flow very well.
  • The piece of scrap lumber should be thick enough so that the staples do not go through to the bottom side of the board.
  • School-aged children who are working on this type of project should do so under the supervision of a parent or other responsible adult.
  • Wear safety glasses when using the staple gun.


  • Photo Credit volume image by Bernard BAILLY from
Promoted By Zergnet


You May Also Like

  • The History of the Rheostat

    A rheostat is a device with a resistance to electric current is dependent on the position of some type of mechanical element...

  • What Is a Rheostat?

    A rheostat is a type of electrical component that provides the capacity to adjust resistance to electrical current. It is frequently equated...

  • How to Use a Rheostat

    A variable resistor called a rheostat has two connections, and hooks up in series with a voltage source to vary its level...

  • How to Wire a 12-Volt Rheostat

    A 12-volt rheostat is a coil of resistance wire with a contact that can slide across the coil. Depending on where the...

  • How to Heat a Wire With a Battery

    There are two ways to use a battery to heat a wire. The first method involves using a wire with a high...

  • How to Select the Correct Rheostat for a Speaker Volume Control

    Speaker volume controls are used to aid in balancing speakers. These are most commonly used with home entertainment systems that are custom-built...

Related Searches

Check It Out

How to Build and Grow a Salad Garden On Your Balcony

Is DIY in your DNA? Become part of our maker community.
Submit Your Work!