Abstract: A transducer including a phototransistor arranged to receive light emitted from a light emitting diode and a movable shield between the transistor and diode. The shield is moved relative to the transistor and diode, within a predetermined range, and there is a linear relationship between the displacement of the shield and changes in the output of the phototransistor. The shield is connected to a member whose displacement is to be measured, and displacement of the member is measured simply by measuring the voltage output of the phototransistor.

Abstract: A showerhead of the type including an inlet end, an outlet end, and a bore defining a passage between the two. Two discs are disposed in the passage, in face-to-face engagement with each other and mounted for relative rotation about a central axis. A plurality of orifices, arranged with their centers spaced at regular intervals around a circle of predetermined diameter, extend through each disc. Each orifice of the downstream disc defines a small port at the downstream face and a large port at the upstream face of the disc. Each orifice through the upstream disc defines at its downstream face a port that communicates with but is smaller than a respective port at upstream face of the downstream disc.