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Pricelist: Retail Price (B2C) Pricelist
5mm Photoresistor LDR Sensor (Pack of 2)

5mm Photoresistor LDR Sensor (Pack of 2)

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SpecificationDetails
Diameter5mm
Light Resistance10kΩ to 20kΩ (at 10 Lux)
Dark Resistance1MΩ to 2MΩ (at 0 Lux)
Max Voltage150V DC
Max Power100mW
Spectral Peak540nm
Response Time20ms to 30ms
Price
₹ 8.47 ₹ 8.47
(Tax included)

Product Description

The 5mm LDR is a reliable and low-cost sensor for detecting ambient light levels. It is made of a semi-conductive material (Cadmium Sulfide) that allows electrons to flow more freely when hit by photons. This change in resistance can be easily measured by a microcontroller using a voltage divider circuit. Because it reacts to a broad spectrum of light similar to the human eye, it is perfect for automatic street lights, solar chargers, and "darkness-activated" alarms.

Key Features

  • Analog Sensing: Provides a continuous range of resistance values, allowing for precise light intensity measurement.

  • Wide Dynamic Range: Resistance shifts from a few hundred Ohms in bright sunlight to several Million Ohms in total darkness.

  • Durable & Reliable: Encapsulated in a clear epoxy resin to protect the sensing element from humidity and dust.

  • Small Form Factor: The 5mm head is compact enough to fit into small 3D-printed enclosures or toy sensors.

  • Breadboard Compatible: Long leads allow for easy insertion into breadboards or direct soldering to PCBs.

Technical Details

  • Material: Cadmium Sulfide (CdS).

  • Operating Temperature: -30°C to +70°C.

  • Quantity: 2 Pieces per pack.

Prototyping and Engineering Tips from Robogears

  • The Voltage Divider: To read an LDR with an Arduino, you must use a voltage divider. Connect one end of the LDR to 5V and the other end to an Analog Pin (like A0). Also, connect a 10kΩ fixed resistor from that same Analog Pin to Ground. This creates a measurable voltage that changes with light.

  • Calibration in Code: Use the analogRead() function to see the raw values (0-1023). For a "Darkness Sensor," check if the value falls below a certain threshold (e.g., < 300) to turn on an LED or a relay.

  • Response Lag: LDRs have a "memory effect" and take a few milliseconds to settle after a sudden change in light. If you need to detect high-speed light pulses (like fiber optic data), use a Photodiode or Phototransistor instead.

  • Directional Shielding: If your LDR is being "tricked" by light from its own LED, place a small piece of black heat-shrink tubing around the 5mm head. This creates a "tunnel" that ensures the sensor only looks in one specific direction.

Package Includes

  • 2 x 5mm Light Dependent Resistors (LDR)

Disclaimer

Avoid exposing the LDR to high-intensity lasers at close range, as the heat can permanently damage the Cadmium Sulfide tracks.