Inside a Power-Cube Transformer

On the other side of the transformer you find twodiodeswrapped in rubber insulation. The diodes act as arectifier, turning the AC current into DC current.

Most transformer cubes that you find around the house produce a low-voltage DC current (3 to 12 volts, and less than an amp of current). DC current is necessary because rechargeablebatteriesstore DC current, because most electronics require low-voltage DC current and becausesmall DC motorsrun directly from batteries and are the least expensive motors available.

The big question remains, however - why can't somebody standardize all of these little cubes?!