The present invention discloses a regular circuitry for reducing ripple resulting from a line voltage transmitting to a secondary side of a power transformer. The regular circuitry electrically connected in parallel with the power transformer includes a ripple sampling circuit, a proportional amplifier circuit, and a reversing amplifier circuit. The ripple sampling circuit selects a sampling ripple from the input port of the power transformer, which is electrically connected in series between a primary side rectification circuit and a secondary side rectification circuit. The proportional amplifier circuit receives the sampling ripple to generate an amplified sampling ripple. The amplified sampling ripple transmits to the reversing amplifier circuit so that a reversed sampling ripple is generated. Thus, the reversed sampling ripple can be input to the output port of the power transformer to superimpose on the signal output from the power transformer to reduce the ripple resulting from the line voltage.