Abstract: A blockage monitor for detecting a blockage in flow of particles includes a sensor body for mounting on a wall of the seed duct and defining a front face flush with the duct surface carrying both an LED light source for projecting light into the interior of the duct and a phototransistor arranged to produce an output signal proportional to the intensity of reflected light received which increases as a seed passes. A separate blockage module counts the output and uses an algorithm for comparing the count with a calibration count to determine whether there is a blockage of the duct. A power voltage is supplied to each sensor using two wires. A test of the sensor includes a pulse in the power voltage so as to generate a corresponding but delayed pulse in the light from the light source.

Abstract: A seed counter for counting seeds flowing through a duct includes a light transmitter on one side of the duct and light receiver on the opposed side of the duct together with an electronic circuit effecting analysis of the signals received by the receiver to generate a seed count value which represents accurately as possible the number of seeds passing through the duct. The transmitter and receiver each comprise a channel-shaped body with diodes at a base of the channel with the channel filled with a translucent potting material facing into the duct. The circuit receives the signals which include for each passage of a seed or a clump of seeds a temporary reduction in light intensity which is converted to a reduction in voltage. Prior to start up the steady state voltage is measured and the current to the transmitter varied to provide a predetermined level of signal at the receiver.

Abstract: A seed counter for counting seeds flowing through a duct includes a light transmitter on one side of the duct and light receiver on the opposed side of the duct together with an electronic circuit effecting analysis of the signals received by the receiver to generate a seed count value which represents accurately as possible the number of seeds passing through the duct. The transmitter and receiver each comprise a channel-shaped body with diodes at a base of the channel with the channel filled with a translucent potting material facing into the duct. The circuit receives the signals which include for each passage of a seed or a clump of seeds a temporary reduction in light intensity which is converted to a reduction in voltage. Prior to start up the steady state voltage is measured and the current to the transmitter varied to provide a predetermined level of signal at the receiver.