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Voltage regulators are built into most power supplies, such as power-banks, USB-plugs and even some batteries. The Arduino Uno has a couple of built-in regulators that can take up to 12 volts and reduce it to 5 and 3.3 volts.
However, it’s sometimes useful to build an independent voltage regulator into a project, for example when we have multiple different voltages needed, or if we can’t source a matching power supply for our project.
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