5mm 5528 LDR Light Dependent Resistor, 10LUX 10-20K

### Lesson Plan: Understanding and Utilizing the 5mm 5528 LDR Light Dependent Resistor in Electronic Circuits

**Introduction**

In this lesson, we will explore the operational principles and practical applications of the 5mm 5528 LDR (Light Dependent Resistor). LDRs, also known as photoresistors, are sensors that change their resistance based on the amount of light they receive. This makes them ideal for various applications such as light sensing, automatic lighting systems, and light-activated switches. By the end of this lesson, you will have a comprehensive understanding of its characteristics and how to incorporate it into your electronic projects.

**Learning Objectives**

Upon completing this lesson, you will be able to:
1. Identify the physical characteristics of the 5mm 5528 LDR.
2. Explain the function of an LDR and its role in electronic circuits.
3. Implement the 5mm 5528 LDR in various circuit configurations to detect and respond to changes in light levels.

**Materials Needed**

– 5mm 5528 LDR Light Dependent Resistor (10LUX 10-20K)
– Breadboard
– Jumper wires
– Raspberry Pi Pico WH
– LED
– 330-ohm resistor
– 10k-ohm resistor (for voltage divider)
– Multimeter (optional)

**Background Information**

The 5mm 5528 LDR is a photoresistor that decreases its resistance with increasing light intensity. It typically has a resistance range of 10k ohms to 20k ohms in varying light conditions, with a 10LUX sensitivity. This makes it suitable for light sensing applications where precise light level detection is required.

**LDR Characteristics**

The 5mm 5528 LDR has two terminals:
– **Light-sensitive surface**: The face of the LDR that should be exposed to light.
– **Resistance change**: The resistance varies inversely with the light intensity falling on the LDR.

**Principles of Operation**

LDRs operate based on the photoconductivity principle:
– **Photoconductivity**: The resistance of the LDR decreases as the light intensity increases due to the generation of more charge carriers in the semiconductor material.
– **Light Sensing**: The LDR can be used in a voltage divider configuration to produce a variable voltage output corresponding to the light intensity.

**Circuit Diagram and Setup**

**Step-by-Step Instructions**

1. **Identify the LDR Terminals**:
– Note that LDRs are non-polarized, so they can be connected in any direction.

2. **Set Up the Breadboard Circuit**:
– Place the 5mm 5528 LDR on the breadboard.
– Connect one terminal of the LDR to the 3.3V pin on the Raspberry Pi Pico WH.
– Connect the other terminal of the LDR to one end of a 10k-ohm resistor.
– Connect the other end of the 10k-ohm resistor to the ground (GND) pin on the Raspberry Pi Pico WH.
– Connect the junction between the LDR and the resistor to an ADC pin (e.g., GP26) on the Raspberry Pi Pico WH.
– Place an LED and a 330-ohm resistor in series on the breadboard to observe the effect of changing light levels.
– Connect the anode of the LED to a GPIO pin (e.g., GP15) on the Pico through the 330-ohm resistor.
– Connect the cathode of the LED to the ground.

3. **Write the Control Code**:
– Open your MicroPython IDE and write the following code to read the LDR value and control the LED:

“`python
from machine import Pin, ADC
from time import sleep

ldr = ADC(26)
led = Pin(15, Pin.OUT)

threshold = 30000 # Set a threshold value for light intensity

while True:
light_value = ldr.read_u16()
if light_value < threshold: led.on() else: led.off() sleep(0.5) ``` 4. **Upload and Test the Code**: - Connect your Raspberry Pi Pico WH to your computer using a Micro USB cable. - Upload the code to the Raspberry Pi Pico WH. - Observe the LED turning on and off based on the light level detected by the LDR. Cover the LDR to simulate darkness and expose it to light to observe the changes. 5. **Optional: Measure Resistance**: - Use a multimeter to measure the resistance of the LDR in different lighting conditions. Observe how the resistance decreases with increasing light intensity. **Applications and Extensions** 1. **Automatic Lighting Systems**: - Use the LDR to create automatic lighting systems that turn lights on or off based on ambient light levels. - Experiment with different threshold values to find the optimal light level for triggering the lights. 2. **Light-activated Alarms**: - Implement the LDR in security systems to detect changes in light levels, such as when a door is opened. - Use the LDR to trigger alarms or notifications when light conditions change unexpectedly. 3. **Light Intensity Measurement**: - Create a simple light meter using the LDR to measure and display light intensity on an LCD or other display module. - Calibrate the system to provide accurate light level readings in different environments. **Summary and Review** This lesson has provided a detailed exploration of the 5mm 5528 LDR Light Dependent Resistor, covering its identification, operational principles, and practical applications in electronic circuits. By understanding and utilizing LDRs, you can create responsive light-sensing systems for a variety of applications, enhancing the functionality and interactivity of your electronic projects.