DC-to-DC converters are electromechanical devices or electronic circuits that convert one direct current voltage or current level to another. In most cases, devices use only one power source. However, if different sub-circuits require different voltages to work properly, one needs to convert the input voltage to a lower or higher level. That can be done with DC-DC converters. Additionally, they stabilize voltages, not letting them drop or rise too much. For example, one of the purposes of car DC-DC converters is to regulate the voltage fluctuations in automotive alternators.