## Introduction: Light Intensity Energy Saver Using Photocells and Thermistors

This instructable is designed to teach you how to save energy by changing light intensity using photocells and thermistors. We will show you how to construct the circuit and code the Arduino using MATLAB.

## Step 1: Problem Statement

Often times in buildings, lights are turned on and give off the same intensity throughout the entire day. With natural light, the overall light intensity in the room changes. We have created a device that can account for the amount of natural light in the room and change the intensity of the artificial light to emit to be more energy efficient. Natural sunlight also heats up a room, so we have added a device that accounts for the temperature change, so the blinds can be lowered or raised to try to maintain the temperature in the room. All of these systems work together to create a more energy efficient product!

## Step 2: Parts and Materials Used

In order to create the circuit displayed above, you will need the following:

(1) Arduino Board

(1) LED light

(1) Photocell

(1) Thermistor

(2) 330 Ohm resistors

(1) Servo

(12) Double-ended wires

(1) USB cable

(1) Desktop with MATLAB

(1) 3D printer and Fusion 360

## Step 3: Creating Your 3D Rod

There are 8 photos to help guide through this step. The first 7 are using Autodesk Fusion, and the last is the final product.

We are essentially designing a rod that can attach to the servo using tape. The servo and the rod work together to act as a curtain, which will regulate the temperature in the room by blocking or letting in "sunlight". Once it is finished, attach the rod to the servo.

Instructions for creating the sketch:

1. Open Autodesk and click on the "Create" pull down tab. Click on the "cylinder" option as shown in the first picture. Leave it at the initial extrusion of 5 mm.

2. Once you have your solid cylinder, click on "Sketch" and then choose the "Center Diameter Circle" option as shown in the third picture.

3. Click on the center of your solid cylinder and change the diameter of the new circle to 9 mm.

4. Click on "Create" again and choose "Extrude". Click on the smaller circle as your plane of choice and change the operation to "join".

5. Extrude the circle to 65 mm or however long or short you want it to be. The sketch is now finished and should look like the seventh picture.

6. Export the sketch and print to your local 3D printer. It should take around 25 minutes and should look like the last photo when completely finished and printed.

## Step 4: Configuration

The Wiring of the breadboard and Arduino is as follows:

Wire from 28a to power

Wire from 24a to ground

Resistor from 24c to 26c

Thermistor from 26e to 28e

Wire from 20a to power

Photocell from 18c to 20c

Resistor from 16e to 18e

Wire from 4a to ground

LED from 4c to 6c

Wire from 16a to ground

Wire from 18a on the breadboard to 'A0' on the Arduino

Wire from 26a on the breadboard to 'A1' on the Arduino

Wire from 6e on the breadboard to 'D3' on the Arduino

Wire from power on the breadboard to '5V' on the Arduino

Wire from ground on the breadboard to 'GND' on the Arduino

Servo:

Wire from power on the breadboard to the Servo

Wire from the ground on the breadboard to the Servo

Wire from 'D9' on the Arduino to the Servo

## Step 5: Coding

The Code is shown in the images above

## Step 6: Put All Steps Together and Enjoy!

Once your 3D rod is attached to your servo, all the wiring is complete, and you've written the whole code, you have your own energy efficient lighting system!