pH Device V3


It is possible to control pH digitally using electronic valves and various solutions(acidic, basic and distilled water). The schematic diagram is attached below. The valves work in such a way that when a voltage is past through the gate, the valves which is normally closed, will open and allow the solution to flow through it. To lower the pH of the solution(make it more acidic), voltage can be past through the valves containing the acidic solution to allow it to flow through and mix with the solution making it more acidic. Likewise for increasing the pH, basic solution can be added. The purpose of distilled water is to dilute the solution. For example if i wan to increase the pH of the solution from 5 to 6, i can just add water instead of a base to increase the pH. This is to prevent the formation of salts. The drain is used to keep the volume of the solution constant to prevent overflowing.

The choice of the acid is Hydrochloric Acid and base is Sodium Hydroxide. The reason is because when they combine, they produce Sodium Chloride which is salt which is not harmful to the plant. The range of pH that we are interested is between the range of 3 to 11. So we will have to use diluted Hydrochloric Acid with pH of 4 and diluted Sodium Hydroxide with pH of 11.


The main problem with V2 was when the draining tube is filled up, it created a suction which causes the tube to drain all the solution in the container (The same method that is used to drain water out of a fish tank). In order to prevent the tube from draining all the solution out, an opening is cut out at the top so that the tube will stop draining the solution when the water level is same in both the container and the tube. The schematic diagram is shown below.

Schematic Diagram


Circuit Diagram


PCB Drawing

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