Abstract: A particle blockage monitoring system employs a flexible piezoelectric particle sensor element in a portion of a particle flow path so that a number of particles traveling in the particle flow path strike the flexible particle sensor element while preventing damage to the particles and maintaining the forward momentum of all the particles in the particle flow path. In order to provide flexibility in monitoring particles of different types and to increase the information rate, the use of a one-shot multivibrator to temporarily store a particle detection signal as in the prior art is avoided. Also, serial sampling of the particle sensor data is avoided to increase the information rate. Instead, a comparator that includes a diode in a feedback loop so as to function as a latch is used in conjunction with a serial shift register that has parallel data input lines.

Abstract: A method and circuit for determining whether a sensor 2 is attached to a connection point 5 of a sensor interface circuit 1 of a seed monitoring system. When it is desired to determine whether a sensor is attached to a connection point, the method applies a time varying detection signal at terminal 3 to the connection point 5 via a reactive element, such as capacitor 4. The connection point 5 is connected to a first input of a comparator 9 having its other input set at a first reference voltage which maintains the comparator in a first state in the absence of a detection signal being applied. Even when a detection signal is applied, the comparator is not driven into a second state if an operable sensor is connected to the connection point 5. When the sensor is not connected to the connection point, or is inoperable, the voltage produced by the detection signal at the first input of the comparator is high enough to trip the comparator into a second state, which may be latched.

Abstract: A sensor (10) detects misfires of combustion cylinders in an internal combustion engine by monitoring the exhaust from the engine. The sensor (10) comprises a spark gap (18) to be situated in exhaust from the engine and a transformer assembly (34). The transformer assembly (34) has an ignition transformer (41a) for providing a potential difference between the electrodes (18a, 18b) of the spark gap (18) and a detection transformer (41b) for sensing the occurrence of an arc across the spark gap (18). An ignition pulse shaper (68) provides an ignition pulse to the ignition transformer (41a) upon receiving a trigger signal from an engine control system (66), and a detection pulse shaper (72) monitors the detection transformer (41b) and forwards an arc detection signal to the engine control system (66) upon detecting an arc across the electrodes (18a, 18b) of the spark gap (18).