Project 2.11.7: Lux Threshold Tuner

Description	This project uses a potentiometer to adjust the light/dark threshold of an LDR, creating a user-calibratable light sensor.
Use case	This project demonstrates a simple user calibration interface where a preferred light sensitivity setting can be selected and stored for use in future applications, such as automatic lighting systems, security systems, or smart home controllers.

Components (Things You will need)

Building the circuit

Things Needed:

• Arduino Uno = 1
• Arduino USB cable = 1
• LDR module = 1
• Potentiometer = 1
• Breadboard = 1
• Jumper wires

Mounting the component on the breadboard

Step 1: Place the Potentiometer and the LDR module on the breadboard following the wiring diagram.

Both the LDR sensor module and the potentiometer require access to 5V and GND. Use the breadboard power rails to distribute power.

NB: Make sure all components are securely placed on the breadboard with correct orientation.

WIRING THE CIRCUIT

Step 2: Connect the D0 pin of the LDR module to Digital Pin 3 on the Arduino Uno using male-to-male jumper wire.

Step 3: Connect the VCC pin of the LDR module to the positive rail pin on the breadboard using male-to-male jumper wire.

Step 4: Connect the GND pin of the LDR module to GND pin on the breadboard using male-to-male jumper wire.

Step 5: Connect one outer pin of the potentiometer to the positive (+) power rail and the other outer pin to the negative (–) power rail on the breadboard using male-to-male jumper wires.

Step 6: Connect the centre (wiper) pin of the potentiometer to Analog Pin A0 on the Arduino Uno using male-to-male jumper wire.

Make sure to connect the Arduino USB cable to the Arduino board.

PROGRAMMING

Step 1: Open your Arduino IDE. See how to set up here: Getting Started.

Step 2: Type the following code in your Arduino IDE: const int ldrPin = 3;, const int potPin = A0;, int threshold; as shown in the image below.

Step 3: Type the following code in your Arduino IDE inside the void setup() function: pinMode(ldrPin, INPUT);, Serial.begin(9600); as shown in the image below.

Step 4: Type the following code in your Arduino IDE inside the void setup() function: threshold = analogRead(potPin);, int lightState = digitalRead(ldrPin);, Serial.print("Threshold: ");, Serial.print(threshold);, Serial.print(" | ");, if (lightState == LOW) {,Serial.println("Dark Environment"); }, else {, Serial.println("Bright Environment"); }, delay(300); as shown in the image below.

Uploading the code

Step 1: Save your code. See the Getting Started section

Step 2: Select the Arduino board and port. See the Getting Started section

Step 3: Upload your code.

OBSERVATION

Rotating the potentiometer changes the selected threshold value, while the LDR sensor reports whether the surrounding environment is bright or dark.

CONCLUSION

This project helps learners understand how to combine multiple components with Arduino to create more complex interactive systems and automation solutions.