Abstract: Disclosed is an electronic sensor and control for monitoring the rate of transport of grain elevator buckets, the electronic control including a metal detector probe for sensing the passage of the buckets past the head and a control module for processing the signals from the head to produce a D-C voltage proportional to the bucket transport rate. Trigger networks responsive to the D-C voltage activate appropriate alarms and shut-down of various phases of the grain elevator operations. An automatic calibration control enables calibration of the D-C voltage for different desired rated speeds of the bucket transport.