How to Build a Simple Electrical Transformer for School

By David Sandoval; Updated April 24, 2017
Transformers work by conducting a variable electromagnetic field along the transformer's core.

A transformer is an electrical device that can be used for one of two functions. The first function of a transformer is to isolate one side of an electrical circuit from direct current electrical energy. Since a transformer works by converting electrical energy into a dynamic electromagnetic field, only alternating current will pass through a transformer. A transformer can also be used to change the voltage of an input AC signal. If the number of windings (also known as "wire turns") around a transformer core is greater at one side of the transformer than the other, the voltage will increase or decrease according to the proportion of wire turns. Many transformers use an iron or nickel core. A simple transformer can be constructed using insulated electrical wire wrapped around a common core.

Use the electrical pliers to cut the wire at the halfway point between the two wire ends. Strip half an inch off of the ends of both wire segments.

Wind the first wire segment around the top of the iron rod, leaving approximately two inches of slack at each end of the wire segment. Color the insulating material at the ends of this wire segment with the marker tip.

Wind the first wire segment around the top of the iron rod, leaving approximately two inches of slack at each end of the wire segment.

To use this isolation transformer, connect the AC power source to the colored wire leads, which serve as the transformer primary. Connect the output device to the other wire leads (the transformer secondary).

About the Author

David Sandoval has served as a trainer and technical writer since 2000. He has written several articles online in the fields of home improvement, finance, electronics and science. Sandoval has an Associate of Applied Science in microelectronics from Northern New Mexico College.