APPARATUS FOR AUTOMATICALLY PREPARING NUTRIENT SOLUTION Russian patent published in 1995 - IPC

FIELD: farm machinery building. SUBSTANCE: this apparatus allows controlling constitution and concentration of nutrient solution depending on intensity of illumination of plants. It includes reservoirs for acid, mineral fertilizer solutions in which calcium is separated from sulfate and phosphate ions, and potassium sulfate solution, which communicate with mixing reservoir via respective batchers and pipelines. Mixing reservoir has tap water supply line, communicates with plant drop watering system and houses primary converters of pH-meter, concentration meter, pK-meter and pNO₃-meter. Signal generated by concentration meter arrives at one of the inputs of differential amplifier second input of which receives signal from plant illumination sensor. Any deviation of concentration of solution from rated value makes differential amplifier to produce output command to control fertilizer solution batcher actuator and feed required amount of fertilizer solution into reservoir. At the same time, signals produced by pK-meter and pNO₃-meter pass adder and antilogarithmic converter to arrive at one of the inputs of differential amplifier whose second input receives signal from plant illumination sensor. Any deviation of ratio between concentrations of potassium and nitrogen nitrate from nominal value causes differential amplifier to shape output command to control potassium sulfate solution batcher actuator. Signal generated by pH-meter enters controller where it is compared with pre-selected pH value. Whenever measured pH value differs from preset one, controller produces command to actuate acid batcher in order to obtain rated pH value. EFFECT: more sophisticated design. 1 dwg