Power supplies for microcontrollers

It is always useful to supply a microcontroller with a power supply unit if you plan to run an already installed program stationary for a long time. A conceivable example would be the recording of room temperature or air humidity with a data logger in the home office. 
If you want to enjoy your project for a long time, we strongly recommend that you observe the maximum values for the current and voltage supply, which depend on the microcontroller.
For an Arduino microcontroller or compatible devices this is 7-12V. If the power supply is <7V, less than 5V could be provided by the microcontroller at the 5V pin. If the power supply is higher than 12V, you run the risk of overheating the voltage regulator on the controller and damaging it.
Please check if the power supply meets the parameters required by the microcontroller before purchasing.