Machines and methods for preparing single-servings of a beverage. In one embodiment, the invention is a pump-attachable device for monitoring and recording a pressure in a vacuum device that includes an adapter enabled to attach to a pressure gauge receiver of an electric pump, and a cable coupled to the pressure transducer which in enabled to attach to a monitor for recording a detected pressure. In an alternative embodiment, the arrangement of the first embodiment is altered by connecting a shorting contactor on one side to the junction of the voltage source inverter, the starting resistor and the starting bypass contactor so as to be short circuited on the opposite side of the shorting contactor. Once an interpolation direction is selected, verifications are performed on the selected interpolation direction in order to rule out erroneous selection. When a wavelength of the incidence light is denoted by \u03bb, a height of the angle limiting filter is denoted by R, and a width of an opening of the angle limiting filter is denoted by d, \u201cd2\u03bbR\u22672\u201d is satisfied. The dial is set so the second set of demarcations matches the first set during positioning of the AHT.