The step up transformer is a device that transforms low AC voltage, large current and small impedance into high AC voltage, small current and large impedance. When there is alternating current through the primary coil, the core (or magnetic core) will be generated in the AC flux, the secondary coil induces a voltage (or current). The input of the transformer must be the alternating current, and its output voltage is proportional to the number of turns of the output or input coil. If a battery is used because it is a DC, the switch circuit must be added to the input circuit to turn it into a changing voltage. In this way, the alternating high voltage power can be obtained at the output end.

Formula and description: the number of the winding of the two lines of transformer is N1 and N2, N1 is primary and N2 is secondary. An induction electromotive force is generated at both ends of the secondary coil by adding an AC voltage on the primary coil. When the N2 is greater than N1, its induced electromotive force is higher than the primary voltage, which is called the step up transformer.