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The Inner Workings of a Toroidal Transformer

At Premier Magnetics, we often get questions from do-it-yourselfers about the various components we sell and which option is right for their particular needs. Our staff is always here to help, but to get you started, we would like to provide some basic information about the use of a toroidal transformer.

Like all types of transformers, it is designed to change AC current without the need for any type of movement or action on the part of the component. Like inductors, all of these transformers are considered to be passive electrical components because they don't actually "do" anything to create the change.

Instead, when the current passes through the windings or the wire wraps around the transformer's core of ferrite or another material, a magnetic field is generated and then collapses. This results in a consistent and specific voltage output. The shape of the transformer itself allows greater efficiency, less EMI or electromagnetic interference, as well as less overall size requirements. This is essential in electronics and other small types of devices.

With the design advantages, a toroidal shape can be measured to be as much as fifty percent more efficient to a standard linear type of core. It can also be mounted in any direction on a board or in a device, making it a very good choice for most applications.

The Details

There is actually a bit more to the job or the effects of a toroidal transformer than that. What happens, in detail, is that the AC current comes into the transformer and constantly changes directions, creating a sine wave pattern going to a peak and falling to zero in both directions. The result is known as cycles, and with AC current it is 60 cycles per seconds, measured as 60 Hertz.

The current into the transformer, which looks like a donut or a lifesaver candy made of ferrite or powdered iron and wrapped with wire, creates a positive magnetic field in the primary coil (the wire). This will peak and collapse, and then a negative field will build and collapse. At each collapse, the voltage goes to zero.

From the primary coil, the magnetic fields building and collapses pass through a secondary coil, also wrapped around the same ferromagnetic core. This, in turn, is the voltage that is used to power the device on the other side of the toroidal transformer.

Through the secondary coil, the voltage is constant and can be determined simply by the number of coils in the wire in the secondary winding compared to the number of coils in the wire of the primary winding. This allows different voltage options in the transformer, suiting any electronic device.