Voltage Converter:

A transformer is used to convert AC voltage. Converting one DC voltage to another involves electronic circuitry (before the introduction of semiconductor electronics, electromechanical equipment was necessary), such as a DC-DC converter. Mains power (also known as household current in the United States) is always alternating current (AC).

Mains converters:

A voltage converter is a device that allows equipment designed for one geographical region's main voltage to operate in another with a different voltage. This type of gadget is known as a voltage converter, power converter, travel adapter, and so on. The majority of single-phase alternating-current electrical outlets in the globe operate at 210-240 V or 100-120 V. A transformer or autotransformer can be employed; because (auto)transformers are intrinsically reversible, the same transformer can be used to step up or step down the voltage by the same ratio. Electronic circuitry allows for the creation of lighter and smaller devices; decreasing voltage electronically is simpler and less expensive than increasing it.

Transformers do not modify the frequency of power; in many areas with 100-120 V, electricity is delivered at 60 Hz, whereas in areas with 210-240 V, energy is supplied at 50 Hz. This may have an impact on the operation of devices that rely on mains frequency (some audio turntables and mains-only electric clocks, etc., although modern equipment is less likely to depend upon mains frequency). Even if the voltage supplied is correct, equipment with high-powered motors or internal transformers meant to work at 60 Hz may overheat at 50 Hz.

Although most mains-powered electrical equipment specifies a single nominal voltage, it actually has a tolerance range above and below that point. As a result, gadgets can typically be utilized on any voltage ranging from 100 to 120 V or 210 to 240 V. In such circumstances, voltage converters just need to be specified to convert any voltage within one range to any voltage within the other, rather than having separate converters for all possible pairs of nominal values (110–220, 117–220, 110–230, etc.)

Converters for devices:

Mains converters;

                        Another requirement is to give low-voltage electricity to a device from mains power; this is often accomplished with a power supply. Most modern electronic gadgets require 1.5 to 24 volts DC; lower-powered devices at these voltages can frequently operate on either batteries or mains electricity. Some devices include a power supply and can be simply plugged into a power outlet. Others rely on an external power supply, which may include a transformer and rectifier or electronic circuitry. Switched-mode power supplies became used in the early twenty-first century; they are smaller and lighter than the once-universal transformer converters and are frequently intended to operate from alternating current mains at any voltage between 100 and 250 V.

Mobile converters:

               Voltage converters can be utilized in automobiles that have 12-volt direct current outlets. For low-power devices, a simple voltage dropper can be used; if more than 12V is necessary, or for high-powered devices, a switched-mode power supply is employed. The output voltage is often in the 1.5-24 V range. There are power sources that output either 100-120 V AC or 210-240 V AC; they are known as inverters since they convert DC to AC rather than changing the voltage. An inverter's output frequency and waveform may not accurately mimic that supplied by mains electricity, but this is usually not a problem.