Liquid flow control arrangement

Claim 1

In an instrument for controlling liquid flow rate in a line, said instrument having light sensitive drop sensing means for sensing the passage of dropS, drop trigger means coupled to and responsive to said drop sensing means providing a pulse at the passage of each drop or a fixed plurality of drops, time trigger means coupled to and triggered by said drop trigger means providing a pulse of a predetermined time width, logic and comparison means coupled to said drop and time trigger means to judge the flow rate, motor means coupled to and driven by said logic and comparison means, line valve means connected to and driven by said motor means to regulate the liquid flow in said line, the improvement therein, wherein said drop trigger means and said time trigger means and said logic and comparison means includes first, second and third monostable multivibrators, said first multivibrator responding to a pulse input supplied by said drop trigger means, a variable resistor capacitor time switch including means for time setting, said switch being coupled to said second multivibrator, said second multivibrator connecting said first and third multivibrators, first, second, and third AND/NAND gates and logic circuitry connecting said gates and said multivibrators providing separate outputs if a succeeding drop is: timely with respect to a preceeding drop, too soon thereafter, or too late thereafter, and a bridge coupled to said gates responsive to said output, said motor means being connected and driven by said bridge.