Digital equipment such as telecommunication, computers systems and instruments use microprocessors that operate at high frequencies allowing them to carry billions of operations per second. A disturbance in the electrical supply lasting just a few milliseconds can affect millions of basic operations. The result may be malfunctioning and loss of data with dangerous or costly consequences (e.g. loss of production). That is why many loads, called sensitive or critical loads, require a supply that is protected. Many manufacturers of sensitive equipment specify very strict tolerances, much stricter than those in the distribution system for the supply of their equipment, one example being Computer Business Equipment Manufacturer’s Association for computer equipment against distribution system disturbances. The design of this uninterrupted power supply (UPS) for personal computer (PC) is necessitated due to a need for enhanced portability in the design of personal computer desktop workstations. Apart from its original functionality as a backup source of power, this design incorporates the unit within the system unit casing, thereby reducing the number of system components available. Also, the embedding of this unit removes the untidiness of connecting wires and makes the whole computer act like a laptop. Not to be left out is the choice of Arduino as an important part of the circuitry. This has eliminated the weight and space-consuming components that make up an original design. The singular use of this Arduino places the UPS under the class of an advanced technology device.