Light Sensor

Definition of Light Sensor and Circuit Examples

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Light sensor is? Definition, working, principle along with examples of simple light sensor circuits and their use around us

Some electrical components use light to influence how they work and function. An example is a light sensor that is often used in lamps.

Such sensors work by utilizing the principle of current and electrical resistance. When light hits the sensor. The resistance increases or decreases according to its position thus regulating the current.

Definition Light Sensor

Light Sensor

Definition light sensor is  an electronic device that can provide changes in the amount of electric charge when there is a change in the intensity of light received and convert it into electrical quantities

In general, sensors are related to functions and work capable of detecting something. For example, animals such as snakes use their tongues to know prey. By the same principle, certain sensors are made on the basis of temperature and heat.

Light is able to affect certain electronic components so that it is used to make sensor devices. For example, you see garden or street lights without wires but can turn on automatically.

The lamp uses a solar cell as a battery and then a light sensor to detect day and night conditions. Examples of the use of light sensors in everyday life can be seen in automatic lights, street lighting, and also television remote signal receiving devices.

Based on the type, the light sensor is divided into two, namely Photovoltaic (Solar Cell / Photocell) which functions to convert the received sunlight into DC electric current. The second is Photoconductiv which functions as a converter of light intensity into changes in conductivity.

Light Sensor Components

Light Sensor

The following list shows some of the components of light sensors that are often used in electronic circuits.

  • LDR

LDR is  a light dependent resistor that works based on light. As the name implies, this is a type of resistor with a resistance value that will change when exposed to light. When the value rises, the electric current will dodge and the light does not turn on. The application can use series or parallel patterns as needed.

  • Photo diode

Another component of the light sensor is the photo diode. This is a type of diode that uses light to activate electricity. When exposed to light, these components will work or vice versa be made inactive.

  • Photo transistor

Another component is a photo transistor that uses additional light resistance. This is a tool that allows for more efficient sensor processes. Similar ways of working and implementing Resistor and Diode.

  • Solar cell

Other examples of light sensors are solar cells for batteries and solar panels. You need to know, wide panels on the roof to capture light using special cell components. Such cells consist of protons and electrons that move when exposed to sunlight. The movement generates electricity and is then directed to the tool or battery.

Working Principle of Light Sensor

Light Sensor

Picture of the Working Principle of the Light Sensor

The working principle of  the light sensor is also classified into two, namely based on the type and components. Passive sensors such as LDRs will receive light and then decrease or increase resistance. Next, an electric current immediately flows or is cut off which is later connected to a lamp or alarm.

The second sensor is capable of performing active functions such as solar cells. After exposure to light, this tool actually converts light into other energy that is more useful. Tools such as cameras also use a type of sensor which is able to capture images and print them.

An LDR light sensor is generally made of a semiconductor disc that has 2 electrodes on its surface. When the light intensity is low (dark), the material will produce a small number of electrons so that only a few electrons will later carry an electric charge.

So when it is dark or low light intensity, the light sensor will be a bad conductor because it has a large resistance when the light intensity is low (dark).

While in conditions of high light intensity (bright), the material on the surface of the light sensor is able to produce more electrons that escape from the atom which will later carry more electrons that carry electric charge.

So when the light intensity is high (daylight conditions), the light sensor will act as a good conductor, where when bright conditions this sensor will have a small resistance compared to dark conditions.

Light Sensor Circuit Example

The light sensor circuit uses several interconnected components with specific functions. A simple example is a lamp because it only requires resistors and transistors.

You make use of the current principle and electrical resistance. As resistance increases, the current does not move and looks for another one to turn on the light.

In general, you can create parallel or series circuits with such sensors. Each electrical circuit This certainly has its own advantages.

If installed in series, the sensor will flow on one path so that it takes a large current and power source to reach the lamp or other components. This method is very effective and practical.

  • Automatic Light Light Sensor

Light Sensor

Light sensors are often found in home lights. Usually, you install lights like this on the terrace so it doesn’t bother at night. When the atmosphere is dark, the lights will turn on automatically and apply when exposed to sunlight during the day.

Lamps with a series of light sensors can be available in electrical and electronics stores. In addition, you may be willing to make your own because the components are easy to obtain and the electronic circuit for the lamp is also simple.

In addition to lights, sensors can be connected to security alarms for example when there are people passing by then the light is dim.

  • LDR Light Sensor Lights in Parks/ Streets

Light Sensor

Light sensor lights are also applied in open places such as parks and roads. When driving, you pass through a road where there are many lights but no wires.

The area is also quite remote so it is very difficult to connect electricity. As a solution, the lamp uses a light sensor. For park use or public street lighting, the lights used are not only ordinary types sometimes also unique in shape that are interesting.

  • Infrared Light Sensor Family

Light Sensor

Infrared sensors also include light but have different waves. The remote control sends command signals to the television and is picked up by receptors. This signal will move certain commands such as volume up or channel switching.

  • Solar Panel Light Sensor Array

Light Sensor

Solar panels also include tools that use light sensors. As mentioned earlier, the sensor is located on the entire surface containing the solar cell. The light captured immediately moves electrons and then the energy is processed into electricity.

On the other hand, parallel light sensors are more often used because they are efficient. The branched system gives the current freedom to flow.

Also Read: Varistor : Definition, Function, Symbol, Type, How It Works

If it is not able to get into branches with high resistance, electric current will switch to another. The parallel system keeps the current flowing so that it is not interrupted even if the lamp is not on to reduce the load


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