Abstract: A system for controlling the feed rate from a vibrating feeder including a device for sensing the amount of materials being discharged from the feeder, an apparatus to change the slope angle of the feeder, and a controller operatively connected to the sensing device and the slope changing apparatus to actuate the apparatus in response to changes in the weight or volume of materials being discharged from the feeder. The sensing device can be connected to a take-away conveyor unit that receives the materials being discharged from the feeder. The slope changing apparatus raises or lowers one end of the feeder to change the slope angle of the feeder while it operates.