the invention provides a novel electric power source unit such as a high - speed pulse power source unit built with a pulse - forming circuit and a dc electric power source unit built with a high - frequency voltage - multipler rectifying circuit having high performance in comparison with conventional units . the inventive unit comprises , as a part of the circuit , at least one ceramic capacitor composed of a ceramic dielectric body made of a strontium titanate - based composition unlike the conventional ones in the prior art comprising barium titanate - based ceramic capacitors . four classes of the preferred compositions are disclosed each containing strontium titanate as the principal component .