A piezoelectric sensor/element is a device that uses the piezoelectric effect, it is basically a device which converts voltage to vibration and vibration to voltage. It normally comes in handy to measure knock (knock  sensor) or vibration (vibration sensor). 

One can use it to for automation using sounds like footsteps, knock,drum etc. Now a days it is also used extensively in power generation projects e.g. Foot Step Power Generation.

This module uses the popular MPU6050 Sensor which includes both a 3 axis accelerometer and a 3 axis gyroscope in a single package.The sensor can be interfaced through a I2C connection which allows an easy and direct interface between the sensor and a micro controller.

The MPU-6000/MPU-6050 family of parts are the world’s first and only 6-axis Motion Tracking devices designed for the low power, low cost, and high performance requirements of smartphones, tablets and wearable sensors.

The 6 Degree of Freedom sensor breakout integrate with the MPU6050 sensor and the low noise 3.3v regulator and pull-up resistors for the I2C bus. So it's available to directly hook up the sensor with the Arduino processors for your robotics,HCI and wearable projects.

The IR Receiver is a type of Diode but different from the LED. It does not emit any light but detects the presence of light. This diode allows some current to pass through it after detecting light and amount of current flow is directly proportional to the amount of light detected and makes a pair with IR transmitter.

The IR Receiver is a type of Diode but different from the LED. It does not emit any light but detects the presence of light. This diode allows some current to pass through it after detecting light and amount of current flow is directly proportional to the amount of light detected and makes a pair with IR transmitter.

An IR transmitter contains an LED that emits infrared light.  Thus the name.  The receiver contains either a photodiode or a phototransistor (usually the latter).  This component passes more or less current depending on the amount of IR light falling on it.

The LED is switched on and off in a coded sequence.

PIR infrared sensor module is based on infrared technology. High sensitivity, high reliability, low power consumption, low voltage operation mode. It’s Compatible with ARDUINO, RASPBERRY PI, AVR, PIC, 8051, etc. Widely used in various auto-sensing electrical equipments for security, automation and lighting control systems because of its unique property of detecting the movement of infrared emitting objects like human bodies. This sensor is equipped with Fresnel lens for improving the detection pattern. All you have to do is give the supply voltage and leave for about a minute to stabilize. Any movement detection causes the sensor output to go high (3.3V). This sensor can be easily used for 220V automatic lighting systems with the help of a simple relay circuit.   

A hall-effect sensor as then name suggests works with the principle of hall-effect and is used to detect magnets. Each side of the sensor can detect one particular pole. It can also be easily interfaced with a microcontroller since it works on transistor logic.

So if you are looking for a sensor to detect magnet for measuring speed of a moving object or just to detect objects then this sensor might be the perfect choice for your project. A3144 is a digital output hall sensor, meaning if it detects a magnet the output will go low else the output will remain high.

This cadmium sulfide (CdS) or light dependent resistor (LDR) whose resistance is inversely dependent on the amount of light falling on it is known by many names including the photo resistor, photoresistor, photoconductor, photoconductive cell, or simply the photocell.

A typical structure of photoresistor uses an active semiconductor layer deposited on an insulating substrate. The semiconductor is normally lightly doped to enable it to have the required level of conductivity. Contacts are then placed either side of the exposed area. The photo-resistor finds many uses as a low cost photo sensitive element and was used for many years in photographic light meters as well as in other applications such as smoke, flame and burglar detectors, card readers and lighting controls for street lamps.

This cadmium sulfide (CdS) or light dependent resistor (LDR) whose resistance is inversely dependent on the amount of light falling on it is known by many names including the photo resistor, photoresistor, photoconductor, photoconductive cell, or simply the photocell.

A typical structure of photoresistor uses an active semiconductor layer deposited on an insulating substrate. The semiconductor is normally lightly doped to enable it to have the required level of conductivity. Contacts are then placed either side of the exposed area. The photo-resistor finds many uses as a low cost photo sensitive element and was used for many years in photographic light meters as well as in other applications such as smoke, flame and burglar detectors, card readers and lighting controls for street lamps.

This cadmium sulfide (CdS) or light dependent resistor (LDR) whose resistance is inversely dependent on the amount of light falling on it is known by many names including the photo resistor, photoresistor, photoconductor, photoconductive cell, or simply the photocell.

A typical structure of photoresistor uses an active semiconductor layer deposited on an insulating substrate. The semiconductor is normally lightly doped to enable it to have the required level of conductivity. Contacts are then placed either side of the exposed area. The photo-resistor finds many uses as a low cost photo sensitive element and was used for many years in photographic light meters as well as in other applications such as smoke, flame and burglar detectors, card readers and lighting controls for street lamps.

This cadmium sulfide (CdS) or light dependent resistor (LDR) whose resistance is inversely dependent on the amount of light falling on it is known by many names including the photo resistor, photoresistor, photoconductor, photoconductive cell, or simply the photocell.

A typical structure of photoresistor uses an active semiconductor layer deposited on an insulating substrate. The semiconductor is normally lightly doped to enable it to have the required level of conductivity. Contacts are then placed either side of the exposed area. The photo-resistor finds many uses as a low cost photo sensitive element and was used for many years in photographic light meters as well as in other applications such as smoke, flame and burglar detectors, card readers and lighting controls for street lamps.

This cadmium sulfide (CdS) or light dependent resistor (LDR) whose resistance is inversely dependent on the amount of light falling on it is known by many names including the photo resistor, photoresistor, photoconductor, photoconductive cell, or simply the photocell.

A typical structure of photoresistor uses an active semiconductor layer deposited on an insulating substrate. The semiconductor is normally lightly doped to enable it to have the required level of conductivity. Contacts are then placed either side of the exposed area. The photo-resistor finds many uses as a low cost photo sensitive element and was used for many years in photographic light meters as well as in other applications such as smoke, flame and burglar detectors, card readers and lighting controls for street lamps.