Abstract: The present invention relates to a Drop Counter for counting a succession of falling liquid drops. The Drop Counter includes a light emitting diode for providing a light beam directed to a falling liquid drop. A photo diode sensor is positioned in side-by-side relation with the light emitting diode and detects reflected light from the falling liquid drop. The photo diode sensor provides an output signal when reflected light is detected and further includes a counter for receiving the output signal and counting the number of times the output signals are received.

Abstract: An array of multiple light-emitting diodes each having a different wavelength are equally spaced around a tubular sample holder facing inwardly. A photo-diode light sensor that detects light transmitted through the sample is mounted to the tubular sample holder at a position directly opposite each light-emitting diode. By selectively turning on one of the LED's and selecting the associated photo-diode exactly opposite it, the light transmission through a solution can be ascertained. A computer is then used to plot the transmission and absorption on a graph for each of the different wavelengths. The circular array of sensors and LED's results in one sensor directly opposite each LED, one sensor off-axis on either side in the forward scatter direction, and one sensor off-axis on either side in the back scatter direction. The combination of back-scattered light and forward-scattered light and transmitted light permits measurements of the turbidity of the sample solution.