Introduction: Engineering Project

This is a circuit that works by having 2 light sources, one bright and one dim, that turn on depending on the presence external light sources such as the sun. The purpose of this circuit is to save electricity during the day by turning on a dim light but still having a bright light for when it is dark.


The materials needed are:

1. LED's (2)

2. Resistors (3) (260 Ohm, 470 Ohm and 1200 Ohm)

3. Photoresistor (1)

4. Breadboard

5. Arduino

6. Wires

Step 1: Photoresistor

The first step in wiring up this circuit is to set up the photo resistor.

Start by connecting the 5V from the Arduino to the power rail on the breadboard. Also connect the ground from the Arduino to the ground rail.

After that, put the photoresistor onto the breadboard and connect the first terminal to the power rail. Then connect the second terminal to a resistor leading to the ground rail and to a wire connecting to one of the Arduino's inputs (in this case, I chose A0).

Step 2: LED's

The second step is to set up the LED's.

This is done by connecting the cathode to the ground rail. Then connect a resistor (260 Ohms) to the anode along with an output from the Arduino (9).

Repeat this process for the second LED but change the resistor to 1200 Ohms and the Arduino output to 5.

Step 3: Coding

The final step is to add the coding.

Start with defining the pins that connect to the photoresistor and LED's along with defining the value of light sensed by the photoresistor. After that, in the setup section define what is an input and what is an output. Then, create an if/else statement where if the light is low then turn on the bright LED, else turn on the dim LED.

Congratulations, the project is finished.