The origin of the electrolytic capacitor or condenser can be traced to the second half of the 19th century when the discovery was made (Wheatstone, Buff, Ducretet) that a film can be formed on aluminum electrochemically and that it will exhibit unidirectional electrical conductance and other peculiar properties. One of the early attempted applications of the electrolytic capacitor was in conjunction with the starting of single-phase induction motors; efforts were also made to utilize it for power factor correction in alternating current circuits. It appears that no extensive use had been made of this device until the early twenties, when its utility in filter circuits supplying rectified plate current to.
