Light Sensor Basics: Types and Functionality

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This page describes the basic function of a light-detecting sensor, often simply called a light sensor.

Definition: It detects the intensity of light and provides an output signal corresponding to that intensity.

Light sensors are commonly used for security purposes in offices and homes. They’re also a key component in automatic street light systems.

Light Sensor

  • The light sensor is a passive device.
  • It converts light energy (in the visible or infrared spectrum) into an electrical signal, as illustrated in the figure above.

Light Sensor Types

There are three main types of light sensors:

  • Photo Conductive Cells: These cells vary their electrical resistance depending on the amount of light they are exposed to.
  • Photo Voltaic Cells: These cells generate an electromotive force (EMF) proportional to the light energy incident upon them. Selenium is a commonly used material in photovoltaic cells, and they are a core element in solar cells.
  • Photo Junction Devices: These are true semiconductor devices, such as photodiodes or phototransistors. They use light to control the flow of electrons and holes across the PN junction.

Photoresistors are semiconductor devices that utilize light energy to control the flow of electrons, and consequently, the current passing through them. The most common type of photo-conductive cell is the Light Dependent Resistor (LDR).

Light Sensor: Advantages and Disadvantages

Light Sensor: Advantages and Disadvantages

Explore the pros and cons of light sensors, including types like photoresistors, photodiodes, and phototransistors. Learn about their applications and limitations.

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10 Practical Applications of LDR Light Sensors

10 Practical Applications of LDR Light Sensors

Explore 10 real-world applications of Light Dependent Resistors (LDRs), also known as photoresistors, showcasing their use in automatic lighting, smart devices, and more.

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Photoresistor Advantages and Disadvantages

Photoresistor Advantages and Disadvantages

Explore the pros and cons of photoresistors, including their light-dependent resistance, cost-effectiveness, limitations in sensitivity, and environmental concerns.

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Phototransistor: Advantages and Disadvantages

Phototransistor: Advantages and Disadvantages

Explore the pros and cons of phototransistors, including applications, sensitivity, limitations, and comparisons to other light-sensing devices.

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Photoelectric Sensors: Advantages and Disadvantages

Photoelectric Sensors: Advantages and Disadvantages

Explore the pros and cons of photoelectric sensors, including their types, benefits like material versatility and long lifespan, and drawbacks like lens contamination.

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