The present invention provides a three-level ac generating circuit and the control method thereof. , continuously supplying the obtained mixture and an aqueous solution of a surface-active agent to an emulsifier, and emulsifying the components at a temperature not exceeding 20\xb0 C. The pivoting arm has a clamp portion extending from the pivot to a position over a seat portion which is adapted to engage a cutter insert. The first control module is for controlling operations of the first circuit module, wherein the first circuit module is externally coupled to the integrated circuit via the shared pin.