5mm LDR Light Dependent Resistor Photoresistor

The 5mm LDR Light Dependent Resistor provides a simple and economical way to detect changes in ambient light. Its resistance decreases as the light intensity increases. Conversely, the resistance rises when the surrounding environment becomes darker.

Therefore, the LDR works well in automatic lighting systems, alarms, toys, and light-sensitive electronic circuits. Its compact through-hole design also fits breadboards, perforated boards, and custom PCBs.

Key Features

• Detects changes in ambient light
• Decreases resistance as light intensity increases
• Increases resistance as the environment becomes darker
• Compact 5mm sensing surface
• Simple two-terminal connection
• Non-polarized component
• Low power consumption
• Suitable for breadboards and PCBs
• Easy to use with microcontrollers
• Ideal for educational electronics

Technical Specifications

• Component Type: Light Dependent Resistor
• Alternative Names: LDR, Photoresistor, Photocell
• Sensor Diameter: Approximately 5mm
• Number of Leads: 2
• Polarity: None
• Mounting Type: Through Hole
• Output Type: Variable Resistance
• Required Interface: Voltage-Divider Circuit
• Recommended Use: Ambient Light Detection

Exact light and dark resistance values may vary between production batches. Therefore, measure the supplied component when a project requires precise thresholds.

How It Works

An LDR behaves like a resistor whose value changes with the amount of light reaching its sensitive surface. More light produces lower resistance, while less light produces higher resistance.

To connect the LDR to Arduino, combine it with a fixed resistor to create a voltage divider. Then, connect the divider output to an analog input pin.

The microcontroller reads the changing voltage and uses it to estimate the surrounding light level. However, an LDR provides relative light detection rather than calibrated lux measurements.

Applications

This photoresistor suits projects such as:

• Automatic night lights
• Street-light prototypes
• Light and dark detectors
• Solar tracking experiments
• Security and alarm circuits
• Display brightness control
• Electronic toys
• Arduino sensor projects
• Robotics projects
• Educational experiments

Important Notes

• The component has no polarity.
• Either lead can connect to either side of the circuit.
• Use a fixed resistor to create a voltage divider.
• Select the fixed resistor according to the required sensitivity.
• Avoid exceeding the electrical limits of the specific LDR model.
• Different LDRs may produce different readings under identical lighting.
• Calibrate the threshold inside the final installation environment.
• Keep the sensing surface exposed to the target light source.
• Do not use this component when accurate lux measurement is required.

Package Includes

• 1× 5mm LDR Light Dependent Resistor