Uninterruptible power supply

The main function of this device is to provide uninterrupted power to your computer or other devices during a power outage.

Working Principle

The device provides uninterrupted power from its built-in rechargeable battery. This battery generates a direct current, which the inverter converts into an alternating current of the desired voltage.

The computer connected to the uninterruptible power supply is normally powered by the mains and the battery is charged. If there is a power failure due to a power line failure, the computer is switched over to the uninterruptible power supply battery.

1 - Input power from the mains

2 - Charging unit

3 - Battery

4 - Inverter

5 - Automatic switch

6 - Mains filter

7 - Output power from the device to the equipment

The models of such devices are equipped with a light indication and audible alarm, which notifies you when autonomous operation begins.

The uninterruptible power supply autonomy time depends on the battery capacity level. The battery capacity is indicated in the certificate of the device or the specifications on the website of the official manufacturer of the uninterruptible power supply.  A five-minute run time is considered sufficient for the typical user, enough time for saving documents and shutting down the computer.

Types

Redundant uninterruptible power supply

It is a simple and affordable uninterruptible power supply. Its efficiency is about 60%. The network filtering is partial, which means that surges and interference in the network, which deteriorate the quality of the equipment, partially reach your computer.

Such an uninterruptible power supply is inexpensive and suitable for home use together with a PC.

Line-interactive uninterruptible power supplies

This type of uninterruptible power supply stabilizes the mains voltage using a switching device. If the mains voltage drops by more than 20%, the uninterruptible power supply automatically switches on and supplies power to the computer. The function of the switching device is to ensure that the UPS switches on only when the voltage is completely lost, not when it is reduced. Therefore, the output voltage of this type of uninterruptible power supply is stable. The efficiency is approximately 85%.

Double conversion uninterruptible power supply

This is the most reliable of the reviewed devices. The double-conversion technology provides almost 100% protection for the equipment. The current rectifier converts the incoming current from the mains to the direct current and the inverter converts the current back to alternating current. The batteries are installed between the rectifier and the inverter. Using this battery connection, delays when switching to stand-alone mode are minimized because the use of the inverter requires no additional switching.

Gaming Devices

The main difference between a gaming device and an ordinary device is the ease of use, ergonomics, and design. It should be pointed out that more high-quality and durable materials are used in gaming devices because they are subjected to high loads during the game.

Computer Gaming Mouse

The following factors are taken into consideration by the developers when designing a gaming mouse:

• Analysis of a comfortable and ergonomic shape for the user, because gamers may spend a long time keeping the mouse in their hand. At the same time, the hand should not get tired of the mouse and it should not cause any hand diseases. Gaming mice are supplied with special 4-gram mouse weights that increase the mouse weight. Increased mouse weight gives the user a better feel of the mouse;
• High-quality materials. Comparatively, the approximate number of buttons presses before they break down is 5 million times for ordinary mice, and 50 million times for gaming mice;
• Mouse sensor accuracy. DPI (Dots Per Inch) is the number of dots per inch, it means how many dots the mouse sensor can count from the surface. Generally standard for usual mice is 800 DPI, but for gaming mice, this number is up to 12,000 DPI.  The higher this value is, the smoother the mouse cursor moves and the smoother the controller reads the user's hand movements;
• Additional keys. These keys can be located on the sides of the mouse or on top of it. They are necessary for increasing mouse functionality. Additional keys can be set up for any command;
• Bright and memorable design with RGB backlighting.

Computer gaming keyboard

In addition to convenient shape, additional keys, and RGB backlighting, gaming keyboards mainly use mechanical key switches. They increase the lifetime of the keyboard.

Also, some gaming keyboards are equipped with additional USB connectors, as well as ports for headphones and microphones.

The gaming keyboard is characterized mainly by the wired type of connection to the computer. The wireless type of connection can cause delays in data transfer and the batteries in the keyboard can run out at the wrong time.

Audio gaming headset

Manufacturers pay attention to comfort and weight in the design of the audio headset. They use a wider range of sound frequencies and improved noise isolation from external factors

Gamepad

This is the main input device for game consoles, but it is also actively used in conjunction with PCs. The gamepad allows you to control your video game character more fluidly than with a keyboard and mouse, due to the force of the sticks.

Gamepads have several advantages over a keyboard and mouse:

• The vibration creates a deeper immersion in the game;
• Optionally, you can set the output from the monitor to the TV and play with the wireless gamepad from the comfort of your couch in front of the big screen.

Joystick

Game controllers are often called joysticks. However, this input device is designed for playing flight simulation games.

Car steering wheel and pedals

This device is designed mainly for racing games.  Combining the steering wheel, pedals, and a special fixed race seat chair creates the feeling of a real car in a video game.

Wireless modem

A wireless modem is used to access the Internet via cell phone operators' networks.

Description

• It is convenient to use in travel and in any situation where there is no access to a Wi-Fi network. It integrates into ATMs, vending machines, security systems, vehicles, remote control systems, etc.;
• Different mobile network rates can be used;
• Easy to install.

USB modem

It is connected to a laptop or tablet via a USB port. It looks like a flash drive.

It only connects one gadget to the Internet.

Standard Networking

Modems can use different standard networks. They differ from each other in the speed of data transmission and the quality of the received connection.

GSM, GPRS, and EDGE

These are the mobile communication standards for 2G. Data rates range from 14 Kbps to 400 Kbps. On your smartphone, this communication standard is indicated by the letter E.

3G

• UMTS – Data transfer rate is 284 Kbps
• HSPA – Data transfer speed is 1.8 Mbps
• HSPA+ – Data transfer speed is up to 42 Mbps

4G (LTE)

4G has a data transfer rate of up to 300 Mbps, while LTE-A has a data transfer rate of up to 1Gbps.

A 4G-supported modem, in case it cannot catch this standard, switches to 3G, since it automatically supports this standard as well.

5G

This is the new generation of the network, which is just getting started. The speeds can reach 20 Gbps.

Router

A router is designed to distribute incoming Internet signals to multiple consumers: computers, laptops, phones, and other gadgets.

Working Principle

The source of the signal for the router is the Internet service provider with whom you, as a consumer, have a contract. The ISP wire is plugged into a special WAN (or Internet) connector on the router.

Furthermore, the router receives the incoming signal from the source and, using a special routing table, distributes it to several consumers. The routing table prescribes and selects the shortest possible addresses to the connected devices. Internet data from the router is only sent to active devices. If you turn off a gadget connected to the router, the router will stop transmitting data to the address corresponding to that device.

Router buttons and connectors

1 - Power on and off button

2 - Connector for connecting the power supply of the device

3 - WAN (or Internet) connector for the network cable (usually blue)

4 - LAN connectors. These are needed to connect your consumers to the router with a network cable (usually yellow)

5 - Reboot button for the router.

Routers can be equipped with a USB connector. It is designed to connect a USB modem with a sim card to the router, which receives the incoming signal.

Interaction with devices

Consumers can connect to the router wired through the LAN ports and the Wi-Fi radio signal.

The router can usually connect from one to four consumers through the wired connection, depending on the number of LAN ports on the router.

The number of gadget connections via Wi-Fi for one router is limited and depends on the router itself and its data transfer rate. If you connect multiple devices via Wi-Fi, the data transfer rate may decrease. In other words, if the input speed of the router is 300 Mbps, and 15 devices are connected to it and working simultaneously, the data transfer rate to devices via Wi-Fi is reduced to 20 Mbps. It is because the router transmits the same rate to the connected devices at the same time. If there are walls, furniture, doors on the way from the router to the connected devices, these obstacles significantly reduce the bandwidth of the routers.

Router settings

Wireless communication protocols

The wireless network works using the 802.11 communication protocol. This protocol has its own varieties: 802.11b and 802.11g. These operate at 2.4 GHz and have limited speeds from 11 Mbps to 54 Mbps. Higher-performance protocols are 802.11ac and 802.11n. They provide higher speeds and 5 GHz frequencies.

Data transfer rate

This is an important parameter on which the performance of the router depends. The data transfer speed is related to the communication protocol.

The 802.11n standard provides speeds of 600 Mbps (at 2.4 GHz and 5 GHz). The 802.11ac standard provides faster speeds than 1300 Mbps at 5 GHz.

Frequency range

Routers can be single-band and dual-band. Its primary frequencies are 2.4 GHz and 5 GHz. The dual-band router supports both of these frequencies because of the two built-in radio modules. The majority of routers operate on the 2.4 GHz frequency. The 5 GHz frequency is preferred by the modern user because it is relatively less crowded.

Number of antennas

The number of antennas in the router allows you to separate data streams and retain a good data rate. Thus, the number of antennas increases the performance of the router.

Built-in firewall

The built-in firewall controls all incoming and outgoing information traffic and protects your home network from spam.

Encryption support

Encryption means the process of encrypting data, which is intended to protect it. An unauthorized user cannot read encrypted data.

Router encryption protocols are WEP, WPA, and WPA2.

Router operating modes

Standard connection

It is supposed that the router is connected via wire, and the Internet signal is distributed via Wi-Fi or wires from the LAN sockets.

WISP mode

It is supposed that the router is connected to the provider through the air rather than by wire, and the Internet signal is distributed via Wi-Fi or by wires from the LAN connectors.

Repeater mode

It is supposed to have two routers. The first receives the signal over the wire from the ISP and distributes the signal. The second router receives the signal from the first router and distributes it to gadgets via Wi-Fi or wires from LAN sockets. This way can be used when it is not possible to run a cable to the second router or when it is necessary to extend the coverage of the Wi-Fi network.

Network Interface Card

This device allows the computer to communicate with the local network and the Internet.

Principle of operation

Once information is received, it is decrypted and transferred to the memory of the network card. Subsequently, the computer processes the received bytes of information.

Network connection

Network connection of the network interface card (NIC) is made via:

• Twisted pair connector

• Optical Connector (SC, ST, MIcz)

There are one or more information LEDs next to the twisted-pair connector, indicating the presence of connection and information transfer.

Speed

Each NIC has a speed limit. So, if your NIC's maximum speed limit is 100 Mbps, but your ISP gives you a fiber-optic speed of 500 Mbps, then your Internet connection speed will not exceed 100 Mbps. In this case, it is recommended that you replace your outdated NIC with a new one. Modern NICs support Internet connection speeds of up to 1 Gbps.

Types

Internal

Internal NICs can be installed in PCI or PCIe slots on the motherboard.

External

Connects to a PC through the USB connector.

Integrated on the motherboard

Network cable connector (1), which interacts with the on-board network card on the motherboard.

Wireless Network Card

If there is no integrated network card, the computer is required to have a network card for wireless data transfer via Wi-fi. Such network cards with an antenna can be connected to the motherboard via a PCI or PCIe connector, and connected to the PC via a USB connector

Projector

A projector is a device designed to render images on a screen and horizontal or vertical surfaces.

Types of projectors for digital images

LCD projector

1 - Projection lamp

2 - Condenser

3 - Lenses

4 - Display

5 - Lens

6 - Luminous flux to the screen

It is constructed like a film projector, only it has a color liquid crystal display inside, instead of film, as in modern displays.

Disadvantages: you can see pixels; the display can burn out due to the bright image.

3LCD projector

1 - Projection lamp

2 - mirrors

3 - LCD monitor

4 - Three channels prism

5 - Display

The system of mirrors divides the luminous flux into three channels (RGB), each of which appears on a different LCD panel. Then the processed light stream is merged into a single image in the three channels prism and displayed on the screen through a lens.

Although the technology is more expensive, this kind of projector no longer shows pixels, and the picture looks saturated.

Compared to an LCD projector, the 3LCD also has a higher noise level because it is necessary to cool three screens instead of one.

LCoS projector

1 - Projection lamp

2 - Mirrors

3 - LCoS panel

4 - Reflecting mirror

5 - Polarizing filters

6 - Prism

LCoS technology may also be called D-ILA, HD-ILA, and SXRD.

It is an improved technology of 3LCD, where a reflective layer has been added behind the liquid crystal layer, so light is reflected and transmitted through the liquid crystal twice upon entering into the display.

The technology has increased the contrast and clarity of the image, but these types of projectors are expensive.

DLP (Digital Light Processing) projector

1 - Projection lamp

2 - Condenser lens

3 - Color wheel

4 - Aspherical lens

5 - DLP chip

6 - lens

7 - Screen

It is called DLP because of the digital light processing. It has one DMD (Digital micromirror device) instead of three LCD screens. The display consists of millions of micromirrors. Each of these mirrors is made of aluminum alloy and can be tilted to one of two positions, differing by 20 degrees. The first position is responsible for white, the second for black. When the position of the mirrors changes rapidly, the pixels on the screen flicker, but the human eye is not able to notice the flicker of the pixels at this speed. The output image is grayed out (because of the rapid change in white and black). However, DLP projectors pass light through a special color wheel to produce a color image.

This disk rotates quickly and paints the pixels one by one.

DLP technology outputs a rich black color on the screen, no grid of pixels is visible, and the mirrors don't burn out because they don't require extensive cooling. That means they are less noisy. Also, these projectors are more compact and portable. However, DLP projectors are less bright than 3LCD projectors.

The older versions of these projectors have a disadvantage: the "rainbow" effect in dynamic and high-contrast scenes. This is related to the rotating color disk. Modern DLP projectors have an increased rotation speed, so the "rainbow" effect disappears.

Moreover, there is a technology of three-matrix DLP projectors that are not inferior to LCD projectors.

Printer

This is a device for printing text or graphic information that is stored in a computer to paper.

Printer Options

Functionality of the device

Printing color

Black and white or color printing.

Printing speed

This indicator shows the number of pages printed per minute.

Printing Cost

This is the cost of replacing the color cartridges in an inkjet printer or replacing the toner roller in a laser or LED printer.

Resolution (dpi)

This indicator shows the print quality of an image or text. The higher it is, the better is the print quality.

For photos good print quality is achieved at a resolution of 2400 dpi, for tables and charts need from 1200 dpi, for text documents 600 dpi is enough.

Photo printing

This is the ability of the printer to print color pictures or photos. For photo printing, the printer must have a color cartridge or cartridges with several shades of different colors. And you also need special paper for photo printing.

Operating system compatibility

This indicator shows its ability to work with various operating systems.

Printer tray layout

The printer tray layout can take up a lot of space. This parameter is relevant for small spaces.

Print format

This parameter indicates the paper size supported by the device. Photo printers support printing in A6 format. For standard printers, the maximum print size is A3; the standard format is A4.

Interface type and wireless connection support

As standard, the printer connects to your computer via USB. It can also be connected to the local network that is used in the office or to Wi-Fi.

Operating principle of printers

Dot-matrix printer

A dot matrix printer creates an image on a sheet of paper using a print head (matrix). This head consists of a set of needles. The set of needles is driven by electromagnets. The head moves along the sheet of paper, and the needles strike it through the ink ribbon.

Matrix printers are no longer used for office or home use. They have slow typing speeds and noisy operations.

Inkjet printer

An inkjet printer works like a dot matrix printer. The image is created from dots, but instead of needle heads, a matrix with liquid dyes (cartridge) is used.

The printing speed of such a printer is 10-30 pages per minute.

Inkjet printers are widespread because of their use in many areas:

• Office - printing A3, A4, A5 sized paper
• Large format printing is used for outdoor advertisement printing
• Interior printers are used for printing posters, stands for interiors
• Photo printers - high-quality print photos

Uninterrupted operation of an inkjet printer is achieved through its regular use. Otherwise, the ink on the print head dries out with prolonged downtime.

Instead of using ink cartridges, inkjet printers can support a continuous ink supply system.

This system delivers ink to the printhead from refillable tanks. The cost of printing is significantly reduced.

Laser printer

The main part of a laser printer is the optical photoconductor drum. It retains an electrical charge on its surface. The laser beam hits the optical photoconductor drum and illuminates individual dots on it. Particles of a special composition (toner) are deposited on the drum and stick only to the charged dots, forming an image. The image is then transferred to the paper under high temperature and pressure.

Laser printers have high print speeds, 80 pages per minute while maintaining high print quality.

LED printer

LED printers use LEDs instead of one laser (laser printer). A different LED is used at each point of the paper print line, so unlike laser technology, the light source remains immovable.

3D printer

This type of printer is designed for printing volume 3D components. They are often used for printing in the medical, industrial, or engineering industries. They are also used for domestic applications such as printing a particular detail. To print a volume 3D figure, you will need a computer program with which you will first need to simulate the model.

Sublimation printers

It is also called a thermal sublimation printer. It can print on a dense surface such as plastic.