The L78M05CV is a fixed output, three terminal precision positive voltage regulator. The L78M05CV fixed voltage regulator is designed with thermal overload protection that shuts down the circuit when subjected to an excessive power overload condition, internal short circuit protection that limits maximum current the circuit will pass and output transistor safe area compensation that reduces the output short circuit as the voltage across the pass transistor is increased. If adequate heat sinking is provided then this positive voltage regulator can deliver over 0.5A output current.

It is an RM065 1M Ohm Trimpot Trimmer Potentiometer.  The potentiometer is easy to mount on a PCB and can be adjusted using a screwdriver.

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.

It is an RM065 20K Ohm Trimpot Trimmer Potentiometer.  The potentiometer is easy to mount on a PCB and can be adjusted using a screwdriver.

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.

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.

A crystal oscillator is an electronic circuit or device which is used to generate a stable frequency with the help of a crystal instead of a tuned circuit. The crystal when vibrates, it acts like a resonator & as a result generates an oscillated frequency. The resonator circuit uses a crystal to generate the oscillation.

The element's compact, ultra-thin design (1.6 mm x 0.8 mm x 0.25 mm) with a wide viewing angle of 120° extends significant advantages for backlighting, indicators, membrane applications, and further enhances design versatility and maneuverability for design engineers developing miniature electronic devices.

Available in multiple colours, this vibrant and low power consumption device operates under current as low as 1 mA and meets industrial temperature ratings of -40°C to +85°C. The distinctive package further provides a remarkable zener diode option to withstand ESD voltage up to 8000 V and provide superior protection against ESD (ElectroStatic Discharge) damages.