10 - Chargers and
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Appliances such as electric kettles, cookers, fires or toasters, need a lot of power and they run directly from the 230-volt mains supply.
Equipment, such as DAB radios, Blue Ray players, or TV's, need much less power. These use internal power supplies/power adapters to reduce the mains voltage down to a few, or tens of volts.
Power Adapters / Chargers
External power adapters and chargers are commonly used to reduce the high mains voltage to safe, useable voltages of 3, 5, 9 or 12 volts.
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At the same time, the power adapters/chargers will usually convert the alternating current (AC), to direct current (DC). This can be seen in the graph on the left - where the flat waveform shows a constant voltage.
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A standard phone charger, or usb computer socket, typically provides a constant voltage of 5 volts and up to 500mA (0.5 amps) of current. | ![]() |
It is important for an internal fuse, or cut-out, to be included in a power adapter. This will automatically provide protection from an overload. This could happen if a circuit connecting to the adapter attempts to draw more current/power than is available.