Basic Electronics 

What is an electronic device?

An electronic device is something that manipulates electricity to do its work. It is often created by using one or more electronic elements that make it possible to manage the flow of electricity into the device. Some electronic devices commonly used today are computers, mobile phones, televisions, Vaccum cleaners, digital cameras, answering machines, mp3 players, video games, microwave ovens, electric kettles, irons, refrigerators, heaters, etc.
Learn basic Electronics || Devices, TV, LED vs LCD, Refrigerator

What is the difference between an “electrical” and an “electronic” device?

The main difference between an electrical device and an electronic device is that electrical devices deal with analog signals, whereas electronic devices with digital signals. Electrical means that the device consists of pure conductive material and electronic devices consist of semi-conductive materials. Electrical devices take the energy of the electric current and transform it in simple ways into some other form of energy – most likely light, heat, or motion. For example, a toaster turns electrical energy into heat that toasts our bread. Electronic devices are designed to manipulate the electrical current itself to coax it into doing useful things. Some electrical devices often include some electronic components in them and vice versa. For example, the toaster contains an electric thermostat that keeps the heat at just the right temperature to make the perfect toast. on the other hand, a television set’s remote control is an electronic device that contains batteries, which are electrical devices.

How do electronic devices manipulate electric current?

Electronic devices manipulate electric current in a way that adds meaningful information to the current. For example, audio electronic devices add sound information to an electronic current, so that we can listen to music or talk on a mobile phone. The radio transmits signals by modulation of electromagnetic waves with frequencies below those visible light. Radio signals vibrate in a pattern that corresponds to the sound(word or music) that they are carrying. Video devices add images to an electric current so we can watch movies.

How is an image produced on the television screen?

A television produces a series of tiny dots (called pixels) on a screen that, when seen as a whole from a distance, appear as an image. The pixels are arranged according to a specific pattern provided by the video signal. Images are formed with pictures. A picture is drawn on the screen one line at a time. The line is a piece of signal that has been decoded and is being drawn from left to right, top to bottom. (Of the screen) The picture itself is formed of thousands of pixels. Think of a pixel as a square that has three lights (red, green, and blue) that can light up individually to make any color (all the colors at one make white light). The signal turns all of these lights into a picture by changing what lights are on or off depending on what color that part of the picture calls for. Every time that a picture is drawn, the screen has been refreshed. By refreshing the screen various times per second, the still picture can turn into a moving picture. The faster the refresh rate, the smoother the picture will animate.

What is a cathode-ray tube?

A cathode ray tube (CRT) is a device controlling electric current through a vacuum in a sealed container made of thin transparent glass. The tube has a narrow end and a wide end. The narrow end contains an iron gun, which shoots out a series of charged particles of electricity. A series of electromagnets guides the particles to specific points on the wider end of the tube, the screen that viewers look at. The screen’s inner surface is coated with phosphors – substances that light up when a charged electrical particle hits them.

How does a plasma screen differ from an LCD screen?

A plasma screen consists of two transparent glass panels with a thin layer of pixels sandwiched in between. Each pixel is composed of three gas-filled cells or sub-pixels (one each for red, green, and blue). Each cell is linked to an electrode, which, when fired, excites the neon and xenon gases contained in the cell. The gases emit charged particles, much like the ion gun, that interact with phosphors coating the glass inside each cell. The phosphors light up, creating the image seen on the television screen. An LCD screen does not excite gases as a plasma screen does. Instead, it has cells that contain a set of red, blue, and green filters, covered by a layer of liquid crystals sandwiched between two pieces of glass. Depending on the display type, each cell is linked to either electrodes or thin-film transistors (TFT), which trigger the necessary cells to create the image. More recent versions of the LCD television use LED as the light source.

How is a LED better than incandescent light sources?

LED has many advantages over incandescent light sources. An incandescent light source emits light as a result of being heated. So, it is exposed to rapid wear and tear. An LED is a semiconductor light source, which emits very little heat. So, it is more durable and requires less electricity. Also, LEDs have improved physical robustness, smaller size, faster switching, and very high brightness. LEDs emit light in a specific direction, reducing the need for reflectors and diffusers that can trap light.

What is a transistor?

A transistor is a semiconductor device with three electrodes namely the base, emitter, and collector, capable of amplification and switching of electronic signals and electric powers. Since its invention in 1947, it has been the fundamental building block of modern electronic devices. A voltage or current applied to one pair of the transistor’s terminals or electrodes changes the current through another pair of terminals. because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Since transistors work primarily as switches and amplifiers, they were first used in sound-related devices.

How does a refrigerator work?

There are two basic principles that make refrigerators work; a gas cools on expansion and the heat flows from the hotter object to the colder object. A refrigerator consists of a refrigerant (a liquid that evaporates inside the refrigerator to create cold temperatures), a compressor (which controls the flow of the refrigerant), the condenser coils (behind the fridge), the evaporator coils (on the inside of the fridge), and an expansion valve. The compressor constricts the refrigerant vapor, raising its pressure, and pushes it into the coils behind the refrigerator. When the hot gas in the coil meets the cooler air temperature of the room, it becomes a liquid. Now, in liquid form at high pressure, the refrigerant cools down as it flows into the coils inside the freezer and the fridge. The refrigerant absorbs the heat inside the fridge, cooling down the air. Finally, the refrigerant evaporates to a gas and then flows back to the compressor, where the cycle starts all over.

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