Weigh feeder system

A weigh feeding machine comprising

• a container for a substance;
• discharge means for discharging the substance from the container at a controllable feed-out rate;
• storage means for storing a first electrical signal corresponding to the desired feed-out rate;
• means for sensing the weight of at least the substance being discharged and for producing a second electrical signal having a characteristic which corresponds to the value of said weight and changes for the different values of weight sensed;
• digital circuit means for sampling the second electrical signal a plurality of times during each of a succession of time intervals;
• storage means for storing the samples of said second electrical signal during each time interval;
• digital computer means for computing a feed-out rate during each such time interval, from the samples taken during one such time interval, and for comparing an electrical signal representative of said computed feed-out rate with the first electrical signal representative of said desired feed-out rate, for producing, as a result of said comparison, a control electrical signal indicative of the desired changes, if any, in the feed-out rate of the discharge means;
• and
• control means for controlling the discharging means in accordance with said control electrical signal to thereby maintain the feed-out of the substance from the container at the desired feed-out rate.