What is infra-red (IR)? Infra-red is an electromagnetic wave who wavelength is between 0.75 microns to 1000 microns (1 micron = 1µm). Since infra-red is out of visible light range, we can’t really see IR with naked eye. However, there is a method to “see” IR which will be shown later on. Some of the infra-red applications includes night vision, hyperspectral imaging, and communications. We also use IR daily in our TV remote or any device remote.
Ultrasonic sensor is a sensor that works on principle similar to radar or sonar. It generates high frequency sound and calculate the time interval between the sending of signal and the receiving of echo. Therefore, ultrasonic sensor can be used to measure distance. HC-SR04 ultrasonic sensor consists of a transmitter, a receiver and a control module.
Distance sensors are widely used in applications that require distance measurement. It is also used in robotics application to detect and measure distance with wall or obstacles. So we are going to look on Analog Distance Sensor SN-GP2Y0A21. As it’s name sounds, it gives out analog readings with changes in distance.
Ever wonder how you can detect temperature in your projects? You can do so by using temperature sensor such as LM35 Precision Centrigrade Temperature Sensor. LM35 is a temperature whose voltage is linearly propotional to Celsius temperature. If you need other units such as Kelvin or Fahrenheit, you can apply some conversion from Celsius.
From Wikipedia, Passive Infra-Red sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects n its field of view. The term passive refers that PIR sensor does not emit or generate any energy for detection purpose.