Abstract: A controller is disclosed which uses pulse width ("PWM") and pulse frequency ("PFM") modulated signals to control a variable to a desired value, the PWM and PFM signals generated through calculation of the difference between the variable and the desired value and then by routing either the PWM or the PFM to the final control element or elements, thereby performing the functions of a proportional and integral controller. Derivative action is also disclosed by differentiating the difference, after filtering, and using the relationship between the difference and the differential to determine the routing of the output signal to the final control element or elements.

Abstract: An optical flow meter comprising a source of light, an optical fiber, a connector, a detector, and output electronics. The optical fiber is connected to the source of light so as to transmit light therethrough. The connector is arranged for attaching the optical fiber in a position generally adjacent to a rotating body. The detector is a photodetector that is arranged to receive light from the optical fiber after the light is reflected by the rotating body. The source of light is a light-emitting diode. The optical fiber is a single optical path. A lens is disposed generally about one end of the optical fiber for directing and focusing light relative to the rotating body. The end of the optical fiber is sealed so as to isolate the end of the fiber from the environment of the rotating body. A beamsplitter is included as an optical coupler between the light-emitting diode, the optical fiber, and the photodetector.

Abstract: An apparatus for controlling the temperature of a supply of water by selective injection of steam is disclosed. The apparatus comprises a water supply conduit which includes a water inlet end and a water outlet end. Steam is supplied to the apparatus by a steam supply conduit which supplies steam to the water supply conduit at a predetermined location between the water inlet end and the water outlet end of the water supply conduit. The steam entering the water supply conduit is controlled by a steam supply control valve located on the steam supply conduit. A pressure differential sensing means senses the difference in pressure along the water supply conduit between a first point in said water supply conduit, upstream of said predetermined location and a second point in the water supply conduit downstream of the predetermined location. A means for controlling the control valve means in response to this sensed pressure differential is also required.