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Good morning, today we're going to talk about the humidity sensor, which is mainly used to detect humidity in soil, to determine whether the plants are going to grow or not.

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The components that we use to make this project possible is a LAV, a resistor of 100 kilohm resistors, with a color code of brown, black, red, and gold.

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Then we use another resistor of 1 kilohm resistor, which is color code is black, brown, yellow and gold.

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Then we use a battery, a transistor, in this case an NPN, and some wires.

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The electrodes at the top act as detectors of humidity.

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They detect the presence of water in the soil.

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The transistor acts like a switch.

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It allows current to flow from the collector to the emitter.

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When a certain amount of electrons pass through the base,

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The resistor that has 100 kilo ohms limits the current from passing to the base.

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and the resistor that has one kilo flows the electrons to the collector and the meter.

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When the electrolytes are dry, they is very limited on no current flowing.

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As a result, no current reaches to the base of the transistor, so it remains off.

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This also means that when there is no humidity, the resistance is considered limited.

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In case 2, when the electrolysis sends the presence of water, a conductive pad appears,

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allowing current to flow from the 100-kilo resistor to the base of the transistor.

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Then the transistor turns on, allowing current to flow from the collector to the emitter.

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Therefore, the LED is going to light up.

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One of the difficulties we had to deal with was that we didn't know how to place the transistor.

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And this got in our way and prevented us from turning on the LED.

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And the other difficulty we had was that since we didn't know how the circuit worked, we placed the components wrong without knowing where they should be placed.

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And the demo, after we apply the irrigation system, will be used for ensuring that the plants receive the right amount of water at the right time.

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So now we are going to show you how the circuit works.

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First of all, we have to connect the board to the battery and then we take the wires

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and place it into the water to see if there is need.

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Then the LED lights up but when we put it when there is dry it doesn't light up because

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there is not a conducted path so in the portal board as we can see the batteries are connected

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to the vertical way so all this part of the board is filled with energy the resistor of

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one kilo ohms is connected to the positive side and the negative side of the board in the vertical

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then we took the led and we connected in the same series of the vertical the resistor and the other

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leg we connected in the other hole then we took the transistor we place it at the same vertical

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of the led and we took the other two legs and we place it in different holes

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then we suit the other transistor 100 kilo ohms and place it near to the transistor

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and then we take the other leg and place it in another hole and for last we took three

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wires to connect them first this wire we collected above the transistor and then we took the other

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side and place it in the negative side then we took the rest two wires we connected where in

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any place of the hole we wanted and then with the other hole we connected to the positive side

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then we were trying to make the relay this is how this recruit is this part here is the thick

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is the control circuit and here is the worker circuit this circuit work when this electrolysis

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sense when when the electrolysis sends the water the signals are sent to the transistor so the coil

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doesn't work because there is humidity so it doesn't have to spread the water to the soil

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but when the electrodes are dry this sends a signal to the transistor to start working

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the circuit so the irrigation starts to happen