TRIAC stands for Triode for Alternating Current. It is a genericized trademark for an electrical device that has 3 terminals and when triggered conducts electrical current in both directions. Its conventional name is bilateral triode thyristor or bidirectional triode thyristor. A thyristor is comparable to a relay where a small voltage induced current can control a lot bigger current and voltage.

Thyristors can be said to be the superset of TRIACs. TRIACs are also relatable to SCRs (Silicon Controlled Rectifiers). TRIACs and SCRs can be distinguished in one characteristic feature i.e. the first one is bidirectional, the flow of current is in both the direction but the later one allows the flow of current in only one direction. Generally, the TRIACs get initiated by the consequence of a positive or a negative potential to the gate but the SCR needs only a positive potential. Once activated, SCRs and TRIACs keep on conducting, regardless of whether the current in the gate ceases, until the principle current dips under a specific level called the holding current.

The GTOs or Gate Turn-Off Thyristors are the same as TRIACs but when the signal in the gate ceases, it provides much more control by turning OFF.

The bidirectional feature of this equipment makes it a good switch for AC or Alternating Current. A trigger, when applied in the main circuit at AC's controlled phase angle, permits control of the average current streaming into a load. This feature is popularly used for managing the speed of dimming lamps, electric heaters, and universal motor.

Factors that affect the working of TRIAC

TRIACS, unlike SCRs, needs appropriate enhancement for its legitimate working. There are some inherent drawbacks like TRIACs Backlash effect, Rate effect, etc. Thus designing it requires proper case.

• Backlash Effect

This effect is one of the most acute Control Hysteresis that grows in the speed control or the lamp control circuits with the help of a Potentiometer for controlling the Gate current. The glowing brightness of the lamp gets a minimum when the potentiometer's resistance increases to the maximum. The lamp never gets ON when the pot is turned back until and unless the resistance of the pot drops to its lowest value. The main reason behind this is the discharging of the TRIAC's capacitor. The triggering pulse is provided to the gate by a Diac. Triac releases through the Diac, generating the Backlash effect.

• Rate Effect

The Rate effect generally takes place due to high inrush current when overwhelming inductive loads switch on and also because of a momentary variation in frequency, voltage or current in the mains.

• Effect of RFI

RFI or the Radio Frequency Interference seriously influences the working of Triacs. Depending on the resistance and the supply voltage of the load, the load current is seen to sharply increase from 0 to a high value whenever the TRIAC switches on the load. This forms pulses of RFI.

This was all regarding TRIACs. Brands that manufacture it are Littelfuse, STMicroelectronics, and NXP. We hope that you liked the article. If you want to refer to the brands then just follow the links as given.

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A thermal cutoff is a safety device for electrical equipment. It ceases the flow of current in a device when heated to a specific temperature. These devices can be reset either automatically or even manually.

Thermal fuse

Thermal fuse is a cutoff that utilizes a fusible link (applicable for only one time). The thermal fuse is not like the thermal switch that gets reset automatically whenever there are temperature drops. On the contrary, it's like an electrical fuse – a one-time-use device that cannot reset itself and needs to be replaced when it is triggered. Thermal fuse is generally used in those situations where overheating is a rare occurrence.

One component is a little meltable pellet that holds down a spring. The spring gets released when the pellet melts completely. As a consequence of this, the circuit breaks up. The NEC Sefuse SF series, Tamura LE series, Hosho Elmwood D series and Microtemp G4A series may manufacture the alloy pellets containing silver, copper, and beryllium to melt at a precise temperature.

Thermal fuses have found its use in heating electrical appliances like hairdryers and coffeemakers. It serves as a safety equipment to cease the flow of current to the device in case of any malfunction that would result in the temperature to ascend to risky levels, potentially lighting a fire. Thermal fuses react only in case of excessive temperature and not during the flow of excess current. This is one of the main differences of the device with a normal electrical fuse. 

Thermal Switch

A thermal switch popularly known as a Thermal Cutout (TCO) or thermal reset is an electrical equipment that opens with a "plink" sound at a higher temperature and closes itself automatically when there is a drop in temperature. The thermal switch is a bimetallic strip that is often encased in a cylindrical glass bulb to shield it from short circuits or dust particles. Another basic configuration utilizes a bimetallic shallow dome-shaped top which "clicks" to an inside out inverted cap when warmed, for example, the "Klixon" brand of thermal cutouts.

The thermal switch can be reused. Thus it is used in temporary places that are user-correctable. Thermal switches are used as thermostats in some cooling and heating system. It is also used in power supplies in case of any malfunction (overload). Another category of thermal switch is the Positive Temperature Coefficient thermistor (PTC). These kinds of thermistors have a “switch” temperature. At this temperature, the resistance rises rapidly and limits the current in the circuit. It is used in motor overheat protection.

Thermal switch is also used in some luminaire, particularly with downlight, where unnecessary heating is well on the way to happen. This might sometime result in "cycling". It is the process where the lights turn on and off after every few minutes. Glimmering radiant Christmas lights take advantage of this impact.

This was all we have about Thermal Cutoffs. Brands that manufacture this equipment are TE Connectivity, Littelfuse and Bourns. Make sure to refer them using the links as provided. Hope you liked the article and Thank you for reading.

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A resettable fuse is a PPTC (Polymeric Positive Temperature Coefficient) device that is a piece of passive electronic equipment utilized in defending against overcurrent faults in electrical circuits. It is also popularly known as polyswitch or a multifuse or a polyfuse. In certain situations, it is noted that this device is much similar to PTC thermistors but instead of charge carrier effects, they are operated on mechanical changes in semiconductors. A PPTC device consists of a voltage rating and a current rating. This electronic device was invented by Gerald Pearson in 1939 at Bell Labs. It was described in US patent #2,258,958.

A PPTC device is manufactured using a crystalline organic polymer matrix which is non-conductive in nature. To make it conductive it is added up with black carbon particle. Several conductive chains of carbons are formed between the crystals when it is cooled. Now as it is good at conducting electricity, the current will pass easily. Passage of a large amount of current through the device will make it heated up. The polymer will expand due to the heating up of the device. As a result, the polymer will change to the amorphous state from its crystalline form. Now as the heat is causing the expansion in the polymer, the carbon particles will start to get separated and the conductive pathways will start to break. As a consequence of this, the device will heat at a much faster rate, expand more and the resistance will be increased. Due to this increase in the resistance the circuital current will decrease. The device still consists of a small amount of current (leakage current) flowing through it which is enough to keep the temperature at a level such that the equipment is at a high resistance state. The range of leakage current is from a few hundred mA at lower voltages to less than a hundred mA at rated voltage. It can be said that latching functionality is one of the characteristic features of the device. 

As soon as the power is removed from the device, the heating caused by the leakage current will cease and the resettable fuse (PPTC) will start to cool down. With the cooling of the device, the original crystalline structure is regained and it gets back to its low resistance state that can hold current. The cooling process of the device generally takes a couple of seconds. 

Resettable fuses are most commonly used in computer power supplies (generally of PC 97 standard), nuclear applications as well as aerospace applications. This device is also used in protecting audio loudspeakers (tweeters). A circuit designed with a PPTC device connected in parallel to the light bulb or a resistor helps in limiting the current through the tweeter to a safer limit. Thus the tweeter will not get damaged if the amplifier is conveying more power that is endurable by it.

This was all we had about Resettable fuses. Brands that make them are TE Connectivity, Littelfuse and Bourns. Make sure to follow them by the links as provided. Thank you for reading up the blog.

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Unlike the CRT (Cathode Ray Tube), the LCDs (Liquid Crystal Display) are not able to produce light of its own. Thus it uses a backlight that provides illumination to it. Backlight provides illumination to the LCD from the back and side of the display panel. Backlight is generally used in small displays such as smartphones, LCD televisions, computer displays, wristwatches, etc.

For color screens, the LED backlighting comes under 2 categories. The first one is the RGB LED backlights and the second one is the white LED backlights.

• RGB LED backlights – The RGB LEDs are made up of red, blue and green LED which can be made to generate several color temperatures of white. RGB LED backlights are generally found in high display devices like HP EliteBook and HP DreamColor LP2480zx monitor. It has also found its use in Dell’s Studio series laptops. RGB LEDs are enabled to provide color gamut to screens. The 3 LED backlights can form a color spectrum that intently coordinates the color filters in the LCD pixels themselves. Using this technique, the filter passband is narrowed, as a result of which a narrow band of spectrum is allowed by each color component through the LCD. As there is a blockage of less amount of light, the efficiency of light is increased. In addition to that, the actual green, blue and red points can be displaced farther out such that more vivid colors can be formed by the display.

• White LED backlights – White LEDs are used frequently in the manufacture of desktop and notebook screens. A white LED is actually a blue LED with yellow phosphor to bring about the discharge of white light.

The LED backlights face several challenges as well. With the increase in the age of an LED, it's very hard to attain uniformity. As 3 different light sources are used i.e. red, green and blue, it means that with aging LED the white point of the display can get displaced at varied rates.  At higher temperature white LEDs faces blue shifts (from 3141K to 3222K for 10 degree Celsius to 80 degree Celsius). Power efficiency may also be kept as a point to note for LEDs.

To defend against the above-discussed challenges in white and RGB LED backlights, NDF Special Light Products has developed an LED technology known as 'advanced remote phosphor'. It uses blue pump LEDs in addition to a sheet having the printing of phosphorous luminescent materials. These are used in those LED applications that require a long life like Air Traffic Control displays, Cockpit display and medical displays.  The principle for this technology is similar to Quantum dots.

With time it is seen that notebook computer is using LED backlights at an immense rate. Since 2005 Sony is taking the help of LED backlights for its VAIO notebook. Asus, Apple, and Dell also made their own LED backlight notebooks by 2007. Today all screens of Apple use LED backlight, be it computer, laptops, etc.

Hope you liked the article on LED backlights. Brands that manufacture them are ELECTRONIC ASSEMBLY, Lumex and Newhaven Display. Make sure to follow them by the links as provided.

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Based on the IEEE 802.11 family of standards, Wi-Fi belongs to the family of wireless technologies used for networking. It is most commonly used in Internet access as well as in local area networking of devices. Devices that utilize Wi-Fi are laptops, desktops, digital cameras, drones, smart TVs, tablets, smartphones, digital audio players, etc.

Wi-Fi utilizes several parts which come under the IEEE 802 protocol family. It is intended to flawlessly interwork with its wired kin, Ethernet. Devices that are compatible can get connected with one other using a wireless access point. Not only this, but they can easily connect with other wired devices as well as with the Internet. There are different versions of Wi-Fi available as declared by IEEE 802.11 protocol standards. They are categorized on the basis of radio bands, also the Max. Ranges, and speeds that might be accomplished. Generally, Wi-Fi uses 5 gigahertz (60mm) SHF ISM and 2.4 gigahertz (120mm) UHF radio bands. These bands are further divided into several channels. A network can share these channels but at any point in time, only 1 transmitter can transmit locally on a particular channel.

There is a relatively high absorption rate by Wi-Fi’s wavebands and it is seen that it works very well in line-of-sight use. Obstructions like pillars, walls, home appliances, etc. immensely decrease the range, but at the same time in a crowded area, it helps in reducing interference among several networks. A hotspot (access point) offers an indoor range of about twenty meters (sixty-six feet) while the new ones brag to provide an outdoor range of one hundred and fifty meters ( four hundred and ninety feet). The coverage area of a hotspot can be as small as a solitary room having walls that block the radio signals, or as wide as several square kilometers with overlapping access points. Along with the time, the productivity and speed of Wi-Fi have expanded. Presently there are several versions of Wi-Fi that can reach the speed of 1Gbit per second and above when attached with compatible hardware at close range.

To get a system connected with a Wi-Fi network, a user should have the name of the network which is known as SSID (Service Set Identifier) and a password. There is a much higher chance for a Wi-Fi to get attacked than the network that is wired. The reason behind this is because anyone present within the range of a particular network with a wireless network interface controller can get access. Thus for the safety and security of a network, we have WPA or Wi-Fi Protected Access. The WPA includes technologies that are made to ensure data moving crosswise over Wi-Fi networks and incorporates solutions for the enterprise as well as personal networks. WPA utilizes the password verification technique to encode Wi-Fi packets to block hackers. With the advent of time, the security landscape has changed and the WPAs are getting stronger and smarter for protecting the data. 

Hope you liked this article on Wi-Fi. Brands that make them are Redpine, Microchip, and Digi International. Make sure to refer them using the links as provided. Thanks for reading.

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Programmable Logic IC Development tools are electrical components that are utilized to set up reconfigurable digital circuits. Before using them in any circuit is important that they are customized (reconfigured) by utilizing a specific program.

Let’s have a look on some variants of the above tools:-

• PLA – It stands for Programmable Logic Array. A PLA consists of a programmable AND gate array and a programmable OR gate array that are linked together to get complemented conditionally to generate an output. On the basis of IBM’s Read-Only Associative Memory (ROAM), the Texas Instruments made a mask-programmable IC in 1970. The device was named as TMS2000. It consisted of eighteen outputs and seventeen inputs with eight JK flip-flops for memory. Later this device was termed as Programmable Logic Array.

• PAL – It stands for Programmable Array Logic. This device consists of a series of transistor cells that are arranged as "fixed-OR, programmable-AND" plane to carry out a famous binary operation i.e. "sum of products" to generate an output. The PAL was introduced by the MMI in 1978. It was small, fast and cheap. It was available in 20 pins 300 mil DIP-packages. Later it was succeeded by AMD which introduced 24 pins 22V10 PAL with several new features.

• GALs – It stands for Generic Array Logic. It was an improved version of PAL which was introduced in 1985 by Lattice Semiconductor. The logical feature of the device was the same as the PAL but this one came with an additional feature of reprogramming. GALs are customized (programmed) utilizing a PAL programmer, or by utilizing the in-circuit programming method on supporting chips.

• CPLDs – It stands for Complex Programmable Logic Device. GALs and PALs are accessible just in little measures, proportionate to a couple of hundred logic gates. CPLDs and PLDs are taken help for larger logic circuits. The first method to program a CPLDs is by a PAL programmer. This method is not convenient for devices that have 100s of pins. The second process is by welding the gadget to its printed circuit board, at that point feed it with a Serial Data Stream from a PC. CPLD comes with a pre-built circuit that deciphers the stream of data and arranges the CPLD to play out its predetermined logical task.

• FPGAs – It stands for Field Programmable Gate Array. Early FPGAs were 82S105 sequencer and 82S100 array by Signetice. It was brought in the year 1970. 82S105 consisted of flip-flop functions while 82S100 was an array of AND terms. FPGAs are made up of a grid of logic gates furthermore, once put away, the information doesn't change, like that of an ordinary gate array. The term “field-programmable” in FPGA means the tool is programmed not by the manufacturer but by the customer. One of the main differences between a CPLDs and an FPGAs is that a CPLD generates logic functions using Sea OF Gate while an FPGA is based on LUTs (Look Up Tables). FPGAs are good for large scale machines while CPLDs are suitable for wide combinational logic applications.

So this was all about programmable Logic IC Development tools. Hope you liked the blog. Companies that manufacture programmable Logic IC Development tools are Lattice, Altera and Terasic Technologies. Make sure to refer them using the links as provided.

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Display modules are popular devices that enrich people with visual information. One of the main motives of display modules is to simplify the sharing of information. There are several displays present but in this article, we are going to focus on two of the most important ones i.e. LCD (Liquid Crystal Display) and LED (Light Emitting Diode). And at the end of the article, we will give a glimpse of OLED (Organic Light Emitting Diode). So without wasting much words let’s begin this blog.

1. LCD (Liquid Crystal Display)

The LCD consists of a flat panel like display which takes the help of light modulating characteristics of liquid crystals. Instead of emitting light directly the liquid crystals use a reflector (or a backlight) to generate images in monochrome or color. LCDs are accessible to show a discretionary or a fixed picture with less info content, which can be shown or covered up, for example, digits, 7 segment displays like in digital clocks or preset words. LCDs have found its way in several applications like computer monitors, aircraft cockpit displays, instrument panels, and LCD televisions. Small LCD screens are used in calculators, smartphones, watches, digital cameras, etc. It is also utilized in consumer electronics products like clocks, video game devices, and DVD players.

2. LED (Light Emitting Diode)

LED is a light-producing semiconductor which discharges light when electric current moves through it. The electrons present in the semiconductor get attached with electron holes and release photons (energy). The shade of the light is dictated by the vitality required for electrons to overcome the bandgap of the semiconductor. White light can be generated by a film of a light-emitting phosphor on the device. LEDs have several advantages over an incandescent light. They are:

• Long Lifetime
• Small Size
• Fast switching
• Improved physical robustness

LEDs have found its use in automotive headlamps, traffic signals, plant growing light, aviation light, etc.

As we have got some ideas regarding LEDs, let's look upon OLED which is one of the popular type of LED present in the market.

                                                               OLED (Organic Light Emitting Diode)

OLED, popularly known as Organic EL diode, is a Light Emitting Diode where the layer of emissive electroluminescent is made up of organic compounds that generates light when an electric current passes through it. OLEDs have found its use in devices like computer monitors, screens used in televisions, portable game console, smartphones, and PDAs. As the OLED display emits visible light there is no use for a backlight. Thus, it is lighter and thinner than the LCD. Even though an LCD uses cold cathode fluorescent lamps but still in a dark room an OLED screen can attain a much higher contrast ratio than an LCD.

Now, OLED can be divided into two categories.

• PMOLED – This stands for Passive Matrix Organic Light Emitting Diode. In this type of display, each row is controlled successively, individually.
• AMOLED – This stands for Active Matrix Organic Light Emitting Diode. It takes the help of a thin film transistor to switch and access each pixel (ON/OFF). Thus, OLED of this category makes large display and high resolution possible.

So this was all about popular Display Modules. Hope you liked this article. Popular brands that makes display modules are 4D Systems, Riverdi and MikroElektronika. Make sure to check them out using the links as provided.

A switch that is operated by rotation is known as a rotary switch. It consists of a rotating shaft that is connected to a terminal. That terminal is responsible for either setting up or breaking up a connection with other terminals. Rotary switches include diverse switch positions that can be established by pivoting the switch axle in different directions. Places where rotary switches can be used are band selectors present in multi-band radios or multi-speed fans and even on electrical metering equipment as range selectors. Till the early 1970s, these switches were also utilized on TV receivers as channel selectors

Generally, rotary switches find their use at places where there is a demand to operate an enormous number of electrical circuits covering a wide range of voltages, power, and current requirements. Presently they are used in applications as follows:

• Computers
• Instrumentation
• Aircraft equipment
• Communications equipment
• Medical equipment
• Industrial controls

A coded rotary selector switch or a coded rotary switch is very much like the normal rotary switch, however, the output is compiled in binary format to lessen pin requirement. It helps in selecting any one of the several choices.

Now let’s have a look upon the structure of this kind of switches.

A coded rotary switch comprises of "rotor" or a shaft that has a "spoke" or a contact arm that projects out from its surface like a cam. Around the rotor, there are several terminals in a circular arrangement. Each of them provides a contact for the shaft through which any distinctive electrical circuits can be associated. The switch is in a layered framework, thus, allowing the utilization of multiple poles. There is a detent component whose operation is initiated when the switch is moved from one position to another. Hence a coded rotary switch gives more prominent pole and throws abilities than simpler switches do. The detent mechanism, as well as the sensor/contact system, determines the total number of switching combinations that are possible.

The switches that are used presently work upon the principle of the "star wheel" mechanism to offer the switching position. Nylon cams are then mounted behind this component and spring-stacked electrical contacts slide around these cams. The cams are cut at locations where the contact should be closed, to sum up the electrical circuit. Some rotary switches are even client configurable in connection to the number of positions.

So this was all about regarding coded rotary switches. Hope you like this article. Brand that makes them are NKK Switches, Apem, and C&K. Make sure to check them out through their links.

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A tactile switch offers the passage of electricity in an electrical circuit whenever the operation section is pressed by the user. The switch serves as a supplier of input signals such that the device gets operated. It is structured with a small impression appropriate for mounting onto the surface area of PCB (Printed Circuit Sheets) made to associate electronic segments to shape electronic circuits.

Whenever pressed the switch gets activated and gets turned off when released. This action is termed as ‘momentary action' which can only be executed at low current and low voltage. There is a wide range of tactile switches available in the market. They are also popular with the name of tact switch or tactile push switch. They have found their use in several areas like industrial machinery, household appliances, commercial equipment, and office equipment. A user can choose any kind of tactile switches for their equipment based on board mounting, size (external dimension) and sealing structure.

Structure

A typical tactile switch has four of the most important things. They are discussed below:

• Cover: The cover defends the switch’s internal parts. The covers are generally made up of metals and are attached to the base. For static electricity protection, some covers also come with a ground terminal.
• Plunger: Basically the plunger is a button that is pressed by the user to activate the switch. It transfers the squeezed force to the contact dome. The arrangement of the plunger surface can be either projected or flat. Generally, plungers are constructed using molded resin but to offer long strokes some come with rubber materials.
• Contact Dome: The contact dome gives a feeling of click and also behaves like a movable contact. When a certain amount of operating force is provided to the plunger the contact dome reverses its shape and connects the 2 fixed circuits electrically to power the circuit. After the removal of this operating force, the dome returns to its original shape. The contact dome that is made up of rubber provides a softer tactile response by increasing the operation stroke. On the other hand, the metal dome provides a sharper tactile response by decreasing the operation stroke.
• Base: The base of the switch is made using molded resin. Resin materials are only used because they can withstand the heat of soldering.

Features

• Click Response: One of the most characteristics features of tact switches is the click response of the button i.e. it gives the individual a chance to feel the reaction from the switch. A feeling of clicking is initiated from the contact dome inside the tact switch. The shape and the material of the contact dome determine the sharpness of the click sense.
• High Durability: The contact dome also serves as a movable contact in tact switches. The contact resistance (resistance value) is formed between fixed contacts and movable contacts whenever the switch is ON. It can be stabled down by utilizing specific materials, shape which provides high durability that is capable of holding a hundred thousand to ten million times of use and surface processing.

This was a brief article regarding tactile switches. Hope you liked reading it. Brands that make it are C&K, Panasonic and E-Switch. Make sure to check them out using their links.

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