How to Make a 120 Volt Step Up Transformer, All About Circuits

Cnstructing a step-up transformer is a good way to learn some of the basic concepts of electronics; it also makes a good science project. The basic materials are easy to find. The wire might be a bit harder to find, but there are electronic parts stores or places online where you can order it.

Construted transformer

Coil the 28 gauge magnet wire tightly around each bolt and tie them together, as shown in the diagram.

For a transformer to be a voltage step-up, the ratio of turns from primary to secondary must be such that the secondary must have more turns.

Here is an example of a ratio for a step-up transformer. A ratio of 1:10 would step up the voltage and current by a factor of ten from primary to secondary. This ratio means that for every coil in the primary, there needs to be ten in the secondary. Ten coils in the primary equals 100 in the secondary for a ratio of 1:10.

Connect your transformer to the power supply, and use the voltmeter to verify your results.

When this project is completed, you will have some basic knowledge of ratios, how transformers work, and some simple knowledge of electronic theory. It is also a good project for hobbyist to learn something about how things work.

Things You'll Need

  • Steel flatbar, 4 pieces
  • Miscellaneous bolts, nuts, washers
  • 28 gauge "magnet" wire
  • Low-voltage AC power supply
  • Voltmeter


  • Do not use a wall socket to power your homemade transformer. It isn't rated for that kind of power.

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