In a control circuit for powering up a switching power supply into a powered output bus, the control circuit is built such that before a turning-on of the switching power supply the controller reference is the slave that follows the bus voltage which is the master. The apparatus automates the known method of rifling a gun barrel. The reducer valve is improved so that a specific gas volume remains in the connected pressurized gas source below a minimum pressure. An amplifier system, in electrical contact with the first and second electrodes, receives first and second electrical signals from the two sensors to generate an electrical waveform.