This project is based off a concept and theory of electronic components and programming due to limited electronic components on hand. Parents always worry about feeding their young children and infants the correct foods. They also worry and need to be conscientious about the temperature of what they are feeding. This setup and project is a way for parents to instantly test the food or liquids just before giving the item to their child. All a parent would need to do is test the food with the thermistor and allow the fan to cool down the item making it safe for the child to eat. Once the fan has come to a stop or slowed way down, the food or liquid is ready to serve to the child.
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Step 1: Gather the Components
1) The first item in the pictures is an Arduino Uno and a breadboard. This will allow you to connect all electrical components to make a complete circuit. The Arduino Uno will also be used to download the code that will control the components.
2) The second item is a USB cord that will allow you to connect from your computer to the Arduino Uno for code downloading as well as the power to the circuit.
3) This is a PNP transistor. Transistors allow for an increased supply of electricity or decreased supply of electricity for a circuit.
4) This is a diode. Diodes control the flow of electricity to a specific direction, so when you hook up the circuit on the breadboard, you need to pay attention to the white line and make sure that it is facing the correct direction.
5) This is a 2.2k Ohm resistor. You will need two of these for the circuit. Resistors are used to restrict the flow of electricity to a certain amount.
6) This is a thermistor. Thermistors output certain values of resistance depending on the temperature it is in.
7) This is a DC motor. DC motors can take direct current electricity in either direction. This will provide the speed of the fan for cooling the food or liquid.
8) The last two items are a set of electrical jumper wires to connect the components completing the circuit.
Step 2: Connect the Circuit
Connect the circuit as shown.
Make sure to take note the direction of the transistor when it is placed in the breadboard. If the flat side is not facing the Arduino Uno it will be backward and the electricity will not flow correctly. Pin 9 is connected to the opposite side of the resistor that is connected in line with the middle prong of the transistor. The bottom prong of the transistor is connected to the negative row of the breadboard. The top prong of the transistor is connected to an open row where the opposite end of the diode from the white line is connected along with one side of the DC motor is connected in that same row. the other side of the DC motor is connected to the row where the diode is connected closest to the white line.
The yellow wire connects with the thermistor is placed in the A0 position on the Uno. In that same row, a 2.2k resistor is connected to the negative row of the breadboard. The third connection needs to be connected to one side of the thermistor, while the other side of the thermistor needs to be connected to the positive row of the breadboard.
The 5V of the Arduino in connected to the positive row of the breadboard. The GND is connected to the negative row of the breadboard.
Step 3: Create the Code
Insert the following code for the project.
The second option is a video that will explain what the parts of the code should do.
Step 4: Run the Program
As I explained in the beginning, I have been forced due to time and lack of potential components needed to fully complete and be successful with the project into a simulation of the project. The attached video explains the concept behind the whole goal of creating a food/liquid tester of temperature while feeding young children and infants.