Flyback transformers, popularly known as the Line Output Transformers, is a special mechanism in converting the energy supply, both voltage and current, into electronic circuits. Although it is termed as a transformer, it works against the typical functions of a conventional transformer, and is exploited more as energy storage equipment. When the primary switch is on, the energy is stored on ferrite core that has the air gap in it. However, when the primary switch is off, the energy is not stored but transferred to the outputs. The current will flow either in the primary winding, or the secondary one, but not both at the same time. Thus, a flyback transformer is often misguided to be an inductor having the secondary windings.
The modern CRT flyback transformers are constructed by winding the primary around a ferrite rod, and then the secondary winding is wound around the primary. This design minimizes the inductance leakage of the primary winding. A ferrite frame is then wrapped around the primary or the secondary assembly that closes the magnetic field lines. An air gap is maintained between the frame and the rod to reduce reminisces. The secondary circuit is twisted with enameled wire, layer on layer, and with the Mylar films between the layers. This way, the wire parts having higher voltage will have more dielectric materials between them. The outer layer of the winding retains the highest voltage, as such, screening and insulation is needed to protect the adjacent components. The higher voltages can be easily achieved with a few turn of the windings, which can provide very high accelerating voltage for a CRT device.
Specifically designed to be used in the CRT display devices, the flyback transformers have recently come up with more useful applications, owing to the demand for a mechanism that produces high currents, as well as, can be relatively used in generating a large number of lower voltages. The smaller size and immense power makes this transformer an easy alternative to the conventional mains transformers. Today, the modern flyback transformer is used in CRT computer monitors and television sets. The frequency and the voltage can vary over a wide range, and depends on the device.
For more practical considerations, in most modern flyback transformers, the rectifier and voltage multiplier comes as a single package on the main circuit board. A thick insulated wire from the transformer is connected to the anode terminal on the side of the picture tube, and is covered by a rubber cap. As such, these are becoming extremely popular for multipurpose applications in various fields.