In order to make the most of your Arduino, you need to connect it to various sensors. This is how they work.
One of the great advantages of Arduino is the scalability of the platform. There are dozens of different sensors on the market, each of which provides unique features that allow you to implement all the project ideas you might have.
Understanding the different sensors available and their applications is actually one of the most important areas you can focus on as an Arduino enthusiast.
If you are serious about this, you will encounter most of these sensors in some basic initial experiments anyway. But it's best to understand their exact role and how to combine them to get the best results.
The Arduino board itself is not very useful. You can upload applets to it and let them perform basic operations, but the hardware is very limited for any real computing use (at least compared to alternative products on the market, such as cheaper Raspberry Pi models).
The real power of this platform lies in the various sensors and other modules that you can connect to the substrate. With just a few jumpers and a few lines of code, you can make basic settings, track specific properties and output related data through Arduino.
The sensors come in different shapes and sizes, and some are designed to be combined with other sensors to obtain a complete effect. However, most of them can be used alone-in some cases, you can even connect them to a separate circuit without even an Arduino controller.
Related: Great Arduino projects for beginners
Let's take a look at some of the most popular sensors you will encounter and see how they work.
As the name suggests, light sensors can be used to detect changes in ambient light levels. This is useful for controlling lighting in various environments. For example, turn off the lights at home when it's dark outside, or adjust the intensity of heating lights when planting plants.
Most Arduino light sensors are implemented by basic LDR (low dynamic range) light sensors, which gives them lower sensitivity compared to more advanced modules such as photodiodes and resistors. Nevertheless, the basic LDR light sensor should provide sufficient sensitivity for most amateur projects.
Temperature sensors are usually implemented using NTC (negative temperature coefficient) or PCT (positive temperature coefficient) thermistors.
From the user's point of view, the only difference is how you should interpret the output value. Some sensors may have internal converters that can handle this part for you in an attempt to standardize the output of most temperature sensors on the market.
The humidity sensor is usually integrated into the temperature sensor, and the two are provided as a paired unit. They can also be found as standalone devices. Most Arduino humidity sensors are capacitive, which means they measure humidity changes through a thin strip of material whose capacitance changes relative to the surrounding humidity.
The name of the motion sensor is a bit misleading. They do not actually detect any movement, but the changes in the level of infrared radiation in the environment.
Almost everything and everyone emits infrared radiation, and humans are particularly "hot" in this regard because their body temperature is higher than the environment. Because of this, when a person walks into the range of the motion sensor, their presence is detected-but the sensor does not measure any actual motion from the beginning.
Most proximity sensors used in Arduino are based on classic infrared designs. The sensors emit direct infrared beams, which are then reflected by any surface they hit.
The sensor detects the returning beam and measures the time difference between the emitted beam and the received beam. In this way, it can estimate the distance the beam travels very accurately without consuming a lot of power.
Accelerometers are used to measure changes in acceleration and can be used to identify changes in position and speed. They are usually realized by a small crystal next to an object of a certain mass, connected to a very sensitive lightweight spring.
Any movement of the entire device will cause the mass to move, thereby exerting pressure on the crystal. The crystal can then convert the pressure change into an electrical signal, indicating how much acceleration is currently being applied to the body.
Related: What is Arduino? What can you use it for? explain
Some sensors have more expensive counterparts. For simple DIY projects, you can usually use a cheaper version of every sensor you need. This is especially true during the prototyping phase, where you usually use jumpers to mix everything together and don't really care about optimizing space or power consumption.
But as you get closer to completing the project, you may need to research more advanced and durable sensors. Some of them may make your device more energy efficient (which may have a huge impact on battery-powered settings), while others may improve the accuracy of the measurements you obtain.
One problem you may encounter when switching from a cheaper sensor to a more expensive sensor is that it may invalidate your initial device calibration. If you perform all the calibrations on a lower accuracy sensor, you may need to adjust some things when you switch to a more advanced version. In this case, it may make more sense to start with a more accurate sensor first.
Sometimes, you can implement your own sensor with the right parts. But you must remember that part of the price you pay for prefabs is not just for basic materials and construction work.
You also invest in products that have been thoroughly tested and calibrated, and you will know that you can rely on the measurement results (within a certain accuracy range) that it provides. Although you can guarantee the same for your colleagues, it may take more time and energy to get them to this point.
Make music with your Arduino by connecting the Arduino to one of these DIY MIDI instruments.
Stefan is a writer who is passionate about new things. He initially graduated as a geological engineer, but later decided to write freely.
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