The Autotransformer from ATO represents a highly efficient voltage transformation solution characterized by a single continuous winding that serves as both primary and secondary, eliminating the need for separate galvanic isolation between input and output circuits. This unique construction enables significant reductions in copper wire and silicon steel sheet usage compared to conventional isolation transformers, resulting in lower material costs, reduced weight, and compact dimensions that facilitate easier transportation and installation while minimizing footprint requirements. The design supports both step-up and step-down voltage conversion configurations, making it versatile for applications requiring small voltage corrections in distribution systems where load isolation from the supply line is not necessary. Key applications include testing electronic devices after repairs, powering vintage amplifiers or radios, compensating for line voltage drops, adjusting temperature in resistance-type heaters, controlling fan speeds, cutting styrofoam, constructing unregulated DC power supplies for high current applications, adjusting AC supply voltage, and roasting coffee beans. The autotransformer features a schematic wiring configuration that allows tapping at various points along the single winding to produce varied output voltages, with the input and output sharing a common electrical connection. This design achieves higher efficiency and greater power transfer capability per unit of physical size than equivalent isolation transformers, though it is important to note that autotransformers do not provide electrical isolation between primary and secondary circuits. The product line accommodates various voltage configurations and is engineered for reliable performance in industrial, commercial, and specialized applications where voltage adjustment takes precedence over isolation requirements.