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External Voltage Selector Switch

PC power supplies support 110V input, 220V input or both. Dual-voltage supplies normally have a selector in the back that controls which voltage you are using; obviously, you want to make sure it is set correctly. There are also some supplies that will automatically support either 110V or 220V without a selector switch, but these are often found only on more expensive units.

Close-up view of a manual voltage selector switch.
This design wisely makes it clear right on the switch
what the current voltage setting is!

Power supplies that support dual voltage input are preferable since they are more flexible, although few people transport their PCs overseas (other than laptops, for which this discussion isn't relevant).

Warning: If your power supply does have a 110/220 switch, make sure it is set correctly, or else! This is usually done for you by the manufacturer of the case (which normally contains the power supply), but I have seen cases that were originally intended for one part of the world end up in a different part, with the wrong external voltage set as the default. Running a power supply set to 220 on 110 V power will probably cause it just to not work, but if you set the switch to 110 and run it on 220 V, damage might result.

Next: Power Conversion Circuitry


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