Abstract: A method of operating a pump can include advancing a stepper motor one or more additional steps in a first direction after detecting a first change in a limit sensor state corresponding to a piston reaching an end of its travel in a first direction. After advancing the stepper motor the additional step or steps in the first direction, the stepper motor can be reversed and advanced in a second direction until a second change in the limit sensor state is detected. The stepper motor can then be advanced in the second direction a predetermined number of steps associated with a full travel of the piston.

Abstract: A method of operating a pump can include advancing a stepper motor one or more additional steps in a first direction after detecting a first change in a limit sensor state corresponding to a piston reaching an end of its travel in a first direction. After advancing the stepper motor the additional step or steps in the first direction, the stepper motor can be reversed and advanced in a second direction until a second change in the limit sensor state is detected. The stepper motor can then be advanced in the second direction a predetermined number of steps associated with a full travel of the piston.

Abstract: A method of operating a pump can include advancing a stepper motor one or more additional steps in a first direction after detecting a first change in a limit sensor state corresponding to a piston reaching an end of its travel in a first direction. After advancing the stepper motor the additional step or steps in the first direction, the stepper motor can be reversed and advanced in a second direction until a second change in the limit sensor state is detected. The stepper motor can then be advanced in the second direction a predetermined number of steps associated with a full travel of the piston.

Abstract: A method of operating a pump can include advancing a stepper motor one or more additional steps in a first direction after detecting a first change in a limit sensor state corresponding to a piston reaching an end of its travel in a first direction. After advancing the stepper motor the additional step or steps in the first direction, the stepper motor can be reversed and advanced in a second direction until a second change in the limit sensor state is detected. The stepper motor can then be advanced in the second direction a predetermined number of steps associated with a full travel of the piston.

Abstract: The particle counter is equipped with a scroll pump adapted to create a gas flow through the measurement chamber with a maximum flow rate of at least 50 liters per minute. Light scattered from particles entrained in the gas flow is collected by an optical system. The product of the smallest diameter of the minimum aperture and the magnification amounts to at least 2 mm. Especially preferred is a minimum aperture with a smallest diameter of at least 2.5 mm and a magnification of at least 1.5. The optical system images a projection of the measurement volume created by intersection of the gas flow and the beam of light onto the active area of the sensor module. The sensor module 13 contains a photomultiplier-tube (PMT). Both sensitivity and accuracy of the particle counter are improved using a larger aperture and greater magnification, which is made possible by use of the photomultiplier tube.

Abstract: The invention is a stationary running machine for indoor use. It offers a natural running gait to the user and also significantly lower impact than when running on a normal running surface. It also has no rotating parts. It uses a spring system to offer an upward force vector to reduce the effective impact weight of the user. By lifting the body up during running, the invention makes it easier for the user to run and reduces the strike impact. The invention also acts to bring the user back to their initial position after each step so that there is no need for a moving conveyor belt, like used in a treadmill, to keep the user in a central position on the machine while the user is running on the machine. The invention may include a suitable running ramp, that can further offer cushioning and/or rebounding properties.