9 Electrically Operated Level Controls for Bulk Storage Bins; and Process Control Instruments-Namely, Digital and Analog Tachometers, Set Point Switches, Shaft Speed Indicators, Zero Speed and Slow Speed Switches, Signal Conditioners, Counters, Totalizers, Position Locators, Electronic Logic Modules which Include Logic Circuitry for Operating Counters, Shaft Rotation Alarm Systems, Voltage Adaptor Kits for Speed Control Systems and Switches, Control Centers for Monitoring the Rotation of Several Shafts, Differential Tachometers, and Combined Tachometer and Totalizer Units for Sensing and Counting Machinery Operations