A method is described for preparing a catalyst precursor suitable for use in the Fischer-Tropsch synthesis of hydrocarbons including 10 to 40% by weight of cobalt oxide crystallites and 0. An inlet provides a pathway for air to flow toward the fuel injectors. Further the superconducting layer is switched between a partially transparent non-superconducting state and a substantially non-transparent superconducting state by a modulation circuit. The differential logic is a combinational circuit in an oscillator alignment state and a sequential circuit in a hard-phase alignment state.