According to known principles of electricity, capacitors access sinusoidal AC circuits, voltage and current in phase difference between the maximum value of 90 °. According to this theory, the C1 and C2 in series connection, and remove the difference from the middle I used it more than the series resistance and capacitance stability. Circuit, D1 and D2, respectively, spread the power of positive half negative half-wave rectified, and added to the A and C1 or C2 charging trigger. Further use to change the trigger time for W phase, as long as the adjustment of the resistance W, you can change the output voltage to achieve the purpose. D1 and D2 is also limited since most of the reverse voltage protection is triggered triac role.