resistor color code calculator is the first band from the left represents the primary good sized figure (digit) of resistance. The 2d band represents the second one good sized digit of resistance. The 0.33 band is the multiplier. The fourth band represents the tolerance cost to which a resistance can vary. The fourth band is generally silver or golden in color.

As noted formerly the maximum vital rule which ought to be observed for studying the resistors is to begin from the primary band (that is at the left side). There are methods to become aware of the primary band from the left side.

The first band is relatively carved in the direction of the leg compared to fourth.
The fourth band of 4 band resistor is specific due to the fact that it's far silver or golden, Both those colours aren't used withinside the first band.
harpersophia 18 october 2021, 8:52

All the electronic devices that we use in our daily life, such as cell phones, laptops, refrigerators, computers, televisions and all other electrical and electronic devices are made with simple or complex circuitry.

ZTT-4.00MG DHW components Warranty 2 years RESONATOR, CERAMIC, 100 V, 4 MHZ, 0.5%, 30 PF, THROUGH HOLE. ZTT series ceramic resonator offers wide frequency range and extended temperature range capabilities with built-in load capability.


Resonators are designed to eliminate a sound wave at a given frequency. Just like waves in the ocean, sound waves have a peak and a trough. Sound waves of a particular frequency bounce inside a resonator. The peak of a sound wave meets through another wave of the same size, canceling out. Sound wave cancellation is what eliminates those annoying noises, giving you a better exhaust note. If you like the sound of your exhaust system but hear the hum a number of turns, a resonator can help you with this problem.

A resonator is a device or system that exhibits resonance or resonant behavior. That is, it naturally oscillates with greater amplitude at certain frequencies, called resonant frequencies, than at other frequencies. Oscillations in a resonator can be both electromagnetic and mechanical (including acoustic). Resonators are used to generate waves of specific frequencies or to select specific frequencies from a signal.Musical instruments use acoustic resonators that produce sound waves of specific tones.

Another example is quartz crystals used in electronic devices such as radio transmitters and quartz watches to produce very precise frequency oscillations. A standing wave in a rectangular cavity resonator A cavity resonator is a resonator in which waves exist in an empty space inside the device. In electronics and radio, microwave cavities made up of hollow metal housings are used in transmitters, receivers and microwave test equipment to verify frequency, in place of tuned circuits which are used at higher frequencies. bass. Acoustic cavity resonators, in which sound is produced by air vibrating in a cavity with an opening, are known as Helmholtz resonators.
harpersophia 16 september 2021, 7:24

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Accurate lighting will let diverse photographers set their devices to the correct settings. Lighting has been used largely for fashion shows, movie sets, stage plays, operas, and concerts. These are events anywhere the audience is not very significant and all attention should be within the performances and the performers anyhow. Although today lighting is known to be in almost every place where it is wanted and designs are made to produce the best lighting effect. Professional Lighting Rental Los Angeles makes it a point to keep an eye on the present trends in production lighting, and matchless gripping tools can straightforwardly recommend you on what the majority of recent options are for your particular commercial film, short film, or promotional video.
AlishaRoy 14 september 2021, 7:13

2N3904 is a NPN transistor hence the collector and emitter will be left open (Reverse biased) when the base pin is held at ground and will be closed (Forward biased) when a signal is provided to base pin. 2N3904 has a gain value of 300; this value determines the amplification capacity of the transistor. The maximum amount of current that could flow through the Collector pin is 200mA, hence we cannot connect loads that consume more than 200mA using this 2n3904 transistor. To bias a transistor we have to supply current to base pin, this current (IB) should be limited to 5mA.

When this transistor is fully biased then it can allow a maximum of 200mA to flow across the collector and emitter. This stage is called Saturation Region and the typical voltage allowed across the Collector-Emitter (V­CE) or Collector-Base (VCB) could be 40V and 60V respectively. When base current is removed the transistor becomes fully off, this stage is called as the Cut-off Region and the Base Emitter voltage could be around 600 mV.

2N3904 as switch:
When a transistor is used as a switch it is operated in the Saturation and Cut-Off Region as explained above. As discussed a transistor will act as an Open switch during Forward Bias and as a closed switch during Reverse Bias, this biasing can be achieved by supplying the required amount of current to the base pin. As mentioned the biasing current should maximum of 5mA. Anything more than 5mA will kill the Transistor; hence a resistor is always added in series with base pin. The value of this resistor (RB) can be calculated using below formulae.
harpersophia 9 september 2021, 7:49

The manufacture of each semiconductor product requires hundreds of processes. After sorting, the entire manufacturing process is divided into eight steps: Wafer Processing, Oxidation, Photography, Etching, Film Deposition, Interconnection, Test, and Package.
Semiconductor Parts Manufacturing Process
Fig 1. Semiconductor Parts Manufacturing Process

1 Wafer Processing
Fewer people know, all semiconductor processes start with a grain of sand. Because the silicon contained in sand is the raw material needed to produce wafers. A wafer is a round slice formed by cutting a single crystal column made of silicon (Si) or gallium arsenide (GaAs). To extract high-purity silicon materials, silica sand is required, a special material with a silicon dioxide content of up to 95%, which is also the main raw material for making wafers. Wafer processing is the process of making and obtaining wafers.

① Ingot Casting
First, the sand needs to be heated to separate the carbon monoxide and silicon, and the process is repeated until the ultra-high purity electronic grade silicon (EG-Si) is obtained. High-purity silicon melts into a liquid, and then solidifies into a single-crystal solid form called an "ingot", which is the first step in semiconductor manufacturing. The manufacturing precision of silicon ingots (silicon pillars) is very high, reaching the nano level.

② Ingot Cutting
After the previous step is completed, you need to cut off both ends of the ingot with a diamond saw, and then cut it into slices of a certain thickness. The diameter of the ingot slice determines the size of the wafer. Larger and thinner wafers can be divided into more units, which helps reduce production costs. After cutting the silicon ingot, it is necessary to add a "flat area" or "indent" mark on the slice, so that it is convenient to set the processing direction based on it as a standard in the subsequent steps.

③ Wafer Surface Polishing
The thin slice obtained through the above-mentioned cutting process is called a "die", that is, an unprocessed "raw wafer". The die surface is uneven, and it is impossible to directly print circuit patterns on it. Therefore, it is necessary to first remove surface defects through grinding and chemical etching processes, then form a smooth surface through polishing and then cleaning residual contaminants.

2 Oxidation
The role of the oxidation process is to form a protective film on the surface of the wafer. It can protect the wafer from chemical impurities, prevent leakage current from entering the circuit, diffusion during ion implantation, and the wafer from slipping off during etching.
Fig 2. Oxidation
The first step of the oxidation process is to remove impurities and pollutants, such as organic matter, metals and evaporation residual moisture with four steps. After the cleaning is completed, the wafer can be placed in a high temperature environment of 800 to 1200 degrees Celsius, and a layer of silicon dioxide is formed by the flow of oxygen or vapor on the wafer surface. Oxygen diffuses through the oxide layer and reacts with silicon to form oxide layers of different thicknesses, which can be measured after the oxidation is complete.
Dry Oxidation and Wet Oxidation Method
According to the different oxidants in the oxidation reaction, the thermal oxidation process can be divided into dry oxidation and wet oxidation. The former uses pure oxygen to produce a silicon dioxide layer, which is slow but the oxide layer is thin and dense. The latter requires both oxygen and high solubility. The characteristic of water vapor is that the growth rate is fast, but the protective layer is relatively thick and the density is low.
Dry Oxidation and Wet Oxidation Method
Fig 3. Dry Oxidation and Wet Oxidation Method
In addition to the oxidizer, there are other variables that affect the thickness of the silicon dioxide layer. First of all, the wafer structure, surface defects and internal doping concentration will affect the rate of formation of the oxide layer. In addition, the higher the pressure and temperature generated by the oxidation equipment, the faster the oxide layer will be formed. In the oxidation process, it is also necessary to use dummy wafers according to the location of the wafers in the unit to protect the wafers and reduce the difference in oxidation degree.

3 Photomask
Photomask is the use of light to "print" circuit patterns onto a wafer. We can understand it as semiconductor parts drawing on the surface of the wafer. The higher the fineness of the circuit pattern, the higher the integration of the product chip, which can only be achieved through advanced photomask technology. Specifically, it can be divided into three steps: photoresist coating, exposure and development.

① Coated Photoresist
The first step in drawing a circuit on a wafer is to coat photoresist on the oxide layer. Photoresist changes the chemical properties of the wafer to become "photographic paper". The thinner the photoresist layer on the surface of the wafer, the more uniform the coating, and the finer the patterns that can be printed. In addition, this step can use the "spin coating" method.
Coating Photoresist
Fig 4. Coating Photoresist
According to the difference of UV light reactivity, photoresist can be divided into two types: positive glue and negative glue. The former will decompose and disappear after being exposed to light, leaving a pattern of unreceived areas, while the latter will polymerize after being exposed to light to let the pattern of the light-receiving part appear.

② Expose
After covering the photoresist film on the wafer, the circuit can be printed by controlling the light irradiation. This process is called "exposure." We can selectively pass light through the exposure equipment. When the light passes through the mask containing the circuit pattern, the circuit can be printed on the wafer coated with a photoresist film underneath.
Fig 5. Exposure
During the exposure process, the finer the printed pattern, the more components can be accommodated in the final chip, which helps to improve production efficiency and reduce the cost of individual components.

③ Development
The step after exposure is to spray developer on the wafer, in order to remove the photoresist in the area not covered by the pattern, so that the printed circuit pattern can be revealed. After the development is completed, it needs to be checked by various measuring equipment and optical microscopes to ensure the quality of the drawing of the circuit diagram.

4 Etching
After the photolithography of the circuit diagram is completed on the wafer, an etching process is used to remove any excess oxide film and only the semiconductor circuit diagram is left. To do this, liquid, gas or plasma is used to remove the unselected parts.
There are two main etching methods, depending on the material used: wet etching that uses a specific chemical solution for chemical reaction to remove the oxide film, and dry etching that uses gas or plasma.
1) Wet Etching
Fig 6. Wet Etching Method
Wet etching that uses chemical solutions to remove oxide films has the advantages of low cost, fast etching speed, and high productivity. However, wet etching has the characteristics of isotropy, that is, its speed is the same in any direction. This will cause the mask (or sensitive film) and the etched oxide film to not be completely aligned, making it difficult to process very fine circuit diagrams.
2) Dry Etching
Dry etching can be divided into three different types:
The first is chemical etching, which uses etching gas (mainly hydrogen fluoride). Like wet etching, this method is also isotropic, which means that it is not suitable for fine etching.
The second method is physical sputtering, that is, ions in the plasma are used to strike and remove the excess oxide layer. As an anisotropic etching method, it has different etching speeds in the horizontal and vertical directions, so its fineness must exceed that of chemical etching. However, the disadvantage of this method is that the etching speed is slow, because it completely relies on the physical reaction caused by ion collision.
Fig 7. Physical Sputtering
The third method is reactive ion etching (RIE). It combines the first two methods, that is, while using plasma for ionized physical etching, and chemical etching is performed with free radicals generated after plasma activation. In addition to the etching speed exceeding the first two methods, RIE can use the characteristics of ion anisotropy to achieve high-definition pattern etching.
Reactive Ion Etching (RIE)
Fig 8. Reactive Ion Etching (RIE)
Now dry etching has been widely used to improve the yield of fine semiconductor circuits. Maintaining the uniformity of full-wafer etching and increasing the etching speed are crucial. Today's most advanced dry etching equipment is supporting the production of the most advanced logic and memory chips with higher performance.

5 Film Deposition
In order to create the micro devices inside the chip, we need to continuously deposit layers of thin films and remove the excess parts by etching, and add some materials to separate the different devices. Each transistor or memory cell is constructed step by step through the above process. The "thin film" we are talking about here refers to a "membrane" whose thickness is less than 1 micron (μm, one millionth of a meter) and cannot be manufactured by ordinary mechanical processing methods. Here the process of putting a thin film containing the desired molecular or atomic unit on the wafer is "deposition."
To form a multi-layer semiconductor structure, we need to fabricate a device stack first, that is, alternately stacking multiple thin metal (conductive) films and dielectric (insulating) films on the surface of the wafer, and then repeat the etching process to remove excess parts and form a three-dimensional structure. Technologies that can be used in the deposition process include chemical vapor deposition (CVD), atomic layer deposition (ALD) and physical vapor deposition (PVD). The methods using these technologies can be divided into dry and wet deposition.

① Chemical Vapor Deposition
Fig 9. Chemical Vapor Deposition
In chemical vapor deposition, the precursor gas chemically reacts in the reaction chamber and generates a thin film attached to the surface of the wafer and by-products that are drawn out of the chamber.
Plasma-enhanced chemical vapor deposition requires the use of plasma to generate reactive gas. This method reduces the reaction temperature and is very suitable for temperature-sensitive structures. In addition, the use of plasma can also reduce the number of depositions, which can often lead to higher quality films.

② Atomic Layer Deposition
Atomic Layer Deposition
Fig 10. Atomic Layer Deposition
Atomic layer deposition forms a thin film by depositing only a few atomic layers at a time. The key to this method is to loop the independent steps in a certain order and maintain good control. Coating the precursor on the wafer surface is the first step, after which different gases are introduced to react with the precursor to form the required substances on the wafer surface.

③ Physical Vapor Deposition
Physical Vapor Deposition
Fig 11. Physical Vapor Deposition
Physical vapor deposition refers to the formation of thin films by physical means. Sputtering is a physical vapor deposition method. Its principle is that atoms of the target material are sputtered out by the bombardment of argon plasma and deposited on the wafer surface to form a thin film.
In some cases, the deposited film can be treated and improved by techniques such as ultraviolet heat treatment.

6 Interconnection
The conductivity of semiconductors is between conductors and non-conductors (ie insulators). This characteristic allows us to fully control the current. Through wafer-based lithography, etching and deposition processes, transistors and other components can be constructed, but they also need to be connected to achieve power and signal transmission and reception.
Metal is used for circuit interconnection because of its conductivity, which is need to meet the following conditions:
Low Resistance: Since the metal circuit needs to pass current, the metal in it should have low resistance.
Thermochemical stability: The properties of the metal material must remain unchanged during the metal interconnection process.
High Reliability: With the development of integrated circuit technology, even a small amount of metal interconnect materials must have sufficient durability.
Manufacturing Cost: Even if the previous three conditions have been met, high cost is not suitable for the mass production.
The interconnection process mainly uses two substances, aluminum (Al) and copper (Co).
Al and Co Interconnection Process
Fig 12. Al and Co Interconnection Process
Aluminum Interconnect Process
This process starts with aluminum deposition, photoresist application, and exposure and development, removing any excess aluminum and photoresist before entering the oxidation process through etching tech. After the foregoing steps are completed, repeat them until the interconnection is completed.
With its excellent electrical conductivity, aluminum is also easy to lithography, etch, and deposit. In addition, it has a lower cost and a better adhesion to the oxide film. The disadvantage is that it is easy to corrode and has a low melting point. In addition, in order to prevent the reaction of aluminum and silicon from causing connection problems, it is also necessary to add a metal deposit to separate the aluminum from the wafer, which is called a "barrier metal."
Aluminum circuits are formed by deposition. After the wafer enters the vacuum state, the thin film formed by aluminum particles will adhere to the wafer. This process is called "Vapour Deposition" and includes chemical vapor deposition and physical vapor deposition.

Copper Interconnection Process
With the improvement of semiconductor process precision and the shrinking of device size, the connection speed and electrical characteristics of aluminum circuits are gradually unable to meet the requirements. For this reason, we need to find new conductors that satisfy the requirements of both size and cost. With its lower resistance, so it can achieve faster connection speed. What’s more, copper is more reliable because it is more resistant to electromigration than aluminum, which is the movement of metal ions that occurs when current flows through the metal.
However, copper does not easily form compounds, so it is difficult to vaporize and remove it from the wafer surface. To solve this problem, we no longer etch copper, but the dielectric materials, so that metal circuit patterns composed of trenches and via holes can be formed, and then copper is filled into the aforementioned to help interconnection, which is called "inlaid process".
Copper Interconnection Barriers
Fig 13. Copper Interconnection Barriers
As the copper atoms continue to diffuse into the dielectric, the insulation of the latter will decrease and produce a barrier layer that prevents the copper atoms from continuing to diffuse. Then a very thin copper seed layer will be formed on the barrier layer. After this step, electroplating can be carried out, that is, the high-aspect-ratio graphics are filled with copper. After filling, the excess copper can be removed by a metal chemical mechanical polishing (CMP) method. After completion, an oxide film can be deposited, and the excess film can be removed by photolithography and etching processes. The full entire process needs to be repeated continuously until the copper interconnection is completed.
It can be seen from the above comparison that the difference between the copper interconnection and the aluminum interconnection is that the excess copper is removed by metal CMP instead of etching.

7 Test
The main goal of the test is to check whether the quality of the semiconductor chip meets a certain standard, thereby eliminating defective products and improving the reliability of the chip. In addition, products that are tested and defective will not enter the packaging step, which helps to save cost and time. Electronic die sorting (EDS) is a testing method for wafers.
EDS is a process for inspecting the electrical characteristics of each chip in the wafer state and thereby improving the semiconductor yield.

1) Electrical Parameter Monitoring (EPM)
EPM is the first step in semiconductor chip testing. This step will test every device (including transistors, capacitors, and diodes) that the semiconductor integrated circuit needs to use to ensure that its electrical parameters meet the standards. The measured electrical characteristic data will be used to improve the efficiency of the semiconductor manufacturing process and product performance (not to detect defective products).

2) Wafer Aging Test
The semiconductor defect rate comes from two aspects, namely, the rate of manufacturing defects (higher in the early stage) and the rate of defects occurring throughout the life cycle afterwards. Wafer aging test refers to testing the wafer under a certain temperature and AC/DC voltage to find out which products may have defects in the early stage, that is, to improve the reliability of the final product by discovering potential defects.

3) Parameters Test
a. Temp Test
High Temperatur: Verify that the chip can work at a temperature that exceeds the maximum temperature by 10% or higher.
Low Temperatur: Verify that the chip can work at a temperature that lower the minimum temperature by 10% or more.
Room Temperatur: Check whether the chip can work at room temperature (25°C).
(The high and low temperature test requirements for storage semiconductors are 85-90℃ and -5-40℃ respectively.)
b. Speed Test
Core: Check whether the core functions are valid.
Speed: Test movement speed.
c. Motion Test
DC: Apply direct current to check whether the current and voltage are normal.
AC: Apply alternating current to test movement characteristics.
Function: Check whether all functions are normal.

After the burn-in test is completed, the semiconductor chip needs to be connected to the test device with a probe card, and then the temperature, speed, and motion test of the wafer can be performed to verify the relevant semiconductor functions. Please see the table for the description of the specific test steps.

4) Repair
Repairing is the most important test step, because some defective chips can be repaired, and you only need to replace the defective components.

5) Ink
The chips that failed the electrical test have been sorted out in the previous steps, but they still need to be marked to distinguish them. In the past, we needed to mark defective chips with special inks to ensure that they can be identified with the naked eye. Today, the system automatically sorts them based on the test data values.

8 Package
Square chips (also called single wafers) of equal size are formed on the wafers processed by the previous several processes. The next thing to do is to obtain individual chips by cutting. The chip that has just been cut is very fragile and cannot exchange electrical signals, so it needs to be processed separately. This process is packaging, including forming a protective shell on the outside of the semiconductor chip and allowing them to exchange electrical signals with the outside. The entire packaging process is divided into five steps, namely wafer sawing, single wafer attachment, interconnection, molding, and packaging testing.

1) Wafer Sawing
To cut countless densely arranged chips from the wafer, we must first grind the back of the wafer until its thickness can meet the needs of the packaging process. After grinding, we can cut along the scribing line on the wafer until the semiconductor chip is separated.
There are three types of wafer sawing techniques: blade cutting, laser cutting and plasma cutting. Blade cutting refers to cutting wafers with diamond blades, which is prone to generate frictional heat and debris and thus damage the wafers.
Laser cutting has higher precision and can easily handle wafers with thin thickness or small scribing line pitch.
Plasma cutting uses the principle of plasma etching, so even if the scribing line pitch is very small, this technology can also be applied.

2) Single Wafer Attachment
After all the chips are separated from the wafer, we need to attach the individual chips (single chip) to the substrate (lead frame). The role of the substrate is to protect the semiconductor chips and allow them to exchange electrical signals with external circuits. A liquid or solid tape adhesive can be used to attach the chip.

3) Bond
Fig 14. Bonding
After attaching the chip to the substrate, we also need to connect the contact points of the two to achieve electrical signal exchange. There are two connection methods that can be used in this step: wire bonding using thin metal wires and flip chip bonding using spherical gold or tin blocks. Wire bonding is a traditional method, and flip-chip bonding can speed up semiconductor product manufacturing.

4) Molding
Fig 15. Molding
After completing the connection of the semiconductor chip, it is necessary to use a molding process to add a package to the outside of the chip to protect the semiconductor integrated circuit from external conditions such as temperature and humidity. After the packaging mold is made as required, we put the semiconductor chip and the epoxy molding compound (EMC) into the mold and seal it. The sealed chip is in its final product.

5) Package Test
The chip that has the final form must pass the final defect test. All that enters the final test is the finished semiconductor chip. They will be put into the test equipment, set different conditions such as voltage, temperature and humidity, etc. for electrical, functional and speed tests. The results of these tests can be used to find defects, improve product quality and production efficiency.

Get full content and video description from Semiconductor Components Manufacturing Steps.
Andrewen 2 september 2021, 9:39

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1 What is Breadboard?
When learning how to build a circuit, the breadboard is one of the most basic parts. There are many small jacks on the breadboard, which are specially designed and manufactured for solderless experiments of electronic circuits. A breadboard consists of plastic block holding a matrix of electrical sockets of a size suitable for gripping thin connecting wire, component wires or the pins of transistors and integrated circuits (ICs). The sockets are connected inside the board, usually in rows of five sockets. Since various electronic components can be inserted or pulled out at will according to needs, welding is eliminated, circuit assembly time is saved, and components can be reused, so it is very suitable for the assembly, debugging and training of electronic circuits.

2 Why are breadboards called breadboards?
The name of the breadboard can be traced back to the era of vacuum tube circuits. At that time, most of the circuit components were large in size. People usually fixed them on a wooden board for cutting bread with screws and nails for connection. Later, the circuit components became more and more smaller, but the name of the breadboard is still used. The breadboard most commonly used today is usually made of white plastic and is a pluggable (solderless) breadboard. It was designed by Ronald J. Portugal in 1971.
It is a process of verifying ideas by creating an initial model. If you are not sure how a circuit will react normally under a given parameter setting, it is best to build a prototype to test it. For those who are new to electronic circuits, the breadboard is a good start. The advantage of a breadboard is that it can hold the simplest and most complex circuits at the same time. If your circuit cannot be accommodated by the current breadboard, you can splice other boards to adapt to all circuits of different sizes and complexity. Such as integrated circuits (ICs). When you try to master how a module works and need to rewire multiple times, you certainly don't want to solder the circuit interface every time. Once you find a problem, you can disassemble each part to prepare for some troubleshooting.

3 How Breadboard Looks like?
The shape of the breadboard is mostly cuboid, with different sizes. The breadboard generally has two layers, the top is a grid shape with double-sided tape adhering to it( you can tore it to fix the breadboard in a certain position). The upper layer of the breadboard is composed of a grid of rows and columns, and there is no conduction between rows.
The whole board is made of thermosetting phenolic resin, and there are metal strips at the bottom of the board. Holes are punched at the corresponding positions on the board so that the components can be in contact with the metal strips when inserted into the board, so as to achieve the purpose of conducting electricity. Generally, every 5 orifice plates are connected by a metal strip. There are two rows of vertical jacks on both sides of the board, also a group of 5. These two sets of jacks are used to provide power to the components on the board.
breadboard layout example
Some breadboards have two columns on the left and right sides. These two columns are customarily used as the positive and negative poles of the power supply (This is not necessarily true, depending on your own usage habits and circuit needs). Each of the five grids in the same column of the two columns is a group, which is conductive. But there is no conduction between columns. Then in the middle part, every five columns of grids form a group, and the five grids in this group are conductive. There is generally a groove in the center of the board, which is designed for the needs of integrated circuit (IC) and chip testing, and is used to separate the left and right parts of a board. Some breadboards do not have two columns on the left and right sides due to the size, but the other structures are the same.
The motherboard uses a glass fiber board with a conductive layer of copper foil, which is used to fix the solderless breadboard and lead out the power terminal.
There may be slight differences in the structure between different breadboards, but they are basically the same.

4 How to Use Breadboards?
You can use breadboard to make quick electrical connections between components- like resistors, LEDs, capacitors, etc, so that you can test your circuit before permanently soldering it together. Without welding and manual wiring, the circuit and components can be tested by inserting the component into the hole, which is convenient to use. Before use, determine which component's pins should be connected together, and then insert them into the same group of 5 small holes.
Example: LED Lighting
1) Materials
One breadboard, several connecting wires (the connecting wires should use needle-shaped wires at both ends), one led light, and one 3V button battery.
2) First, put the battery into the battery holder (this can be bought online), and plug it into the breadboard. Then, insert the battery holder into the left and right parts of the breadboard. Parts are separated by grooves to avoid short circuit between the positive and negative poles of the power supply).
3) Lead two wires from the positive and negative poles of the battery, and then plug the LED into any two grids that are not conductive on the breadboard (the long pin of the led is positive and the short pin is negative), and finally connect the wires from the positive and negative poles of the battery to the two LED segments.

5 Types of Breadboards
1) Solderless Breadboard
A solderless breadboard is a motherboard that does not serve as a base, and does not have a soldering power socket to draw out but can expand a single breadboard. Connect the two poles of the power supply to the sockets on both sides of the breadboard, and then you can plug in the components for experiment (the power supply should be disconnected during the process of inserting the components). When more than 5 components or a set of jacks cannot be inserted, you need to connect multiple sets of jacks with a breadboard cable.
The advantages of solderless breadboards are small size and easy to carry, but the disadvantages are relatively simple, inconvenient power connection, and small area. It is not suitable for large-scale circuit experiments. If you want to use it for large-scale circuit experiments, you need to fix multiple breadboards on a large wooden board with screws, and then connect them with wires.

2) Single Breadboard
A single breadboard is a part with a motherboard as a base and a dedicated terminal for power access, and even some breadboards that can perform high-voltage experiments include ground terminals. This kind of board is more convenient to use, that is, directly connect the power supply to the terminal, and then insert the components for experiment (the power supply should be disconnected during the process of inserting the components) when more than 5 components or a set of jacks cannot be inserted, you need to use breadboard cables to connect multiple sets of jacks.
The advantage of a single breadboard is that it is small in size, easy to carry, and can easily switch on and off the power supply, but it has a small area and is not suitable for large-scale circuit experiments.

3) Composite breadboard
Composite breadboard is a board composed of many solderless breadboards. Generally, 2-4 solderless breadboards are fixed on the motherboard, and then the power cords of each board are connected together with the copper foil in the motherboard. The kind of breadboards is also specially designed for different circuit units to control the power supply, so that each board can carry different voltages according to the needs. The use of the composite breadboard is the same as the single breadboard.
The advantage of the composite breadboard is that it can conveniently switch on and off the power supply, has a large area to carry out large-scale experiments, and is highly mobile, and has a wide range of uses. However, it is large and heavy for carrying, so it is suitable for laboratories and electronic hobbyists use.

6 Basic Principles of Breadboard Wiring
Complete the circuit overlap on the breadboard, different people have different styles. However, no matter what style or habit, the following basic principles must be paid attention to when completing the circuit overlap:
1. The fewer connection points, the better
Each additional connection point actually increases the probability of failure artificially. There are common faults such as impassability in the breadboard hole, loose wire, and broken wire inside.
2. Try to avoid overpasses
The so-called "overpass" means that components or wires ride on other components or wires. Beginner is easy to make such mistakes. It will bring trouble to the replacement of components in the later stage. On the other hand, in the event of a failure, the messy wires can easily make people lose confidence.
3. Try to be as reliable as possible
There are two phenomena that need attention:
① Breadboard integrated circuits are easy to loosen. Therefore, for integrated circuits such as operational amplifiers, it is necessary to press down forcefully. Once it is not reliable, the position needs to be changed.
② The pins of some components on the breadboard are too thin, so please be careful to move them slightly. If you find that they are not secure, you need to change the position.

7 Breadboard Using Tips for Beginners
1) When installing discrete components, it should be easy to see their polarity and signs. After placing the component pins, bend them where needed. In order to prevent the exposed leads from short-circuiting, a wire with a sleeve must be used, and the component pins are generally not cut to facilitate repeated use. Generally, do not insert components with a pin diameter> 0.8mm, so as not to damage the elasticity of the contact piece inside the socket.
2) The pins of integrated circuits that have been used many times must be repaired neatly, the pins cannot be bent, and all the pins should be slightly skewed outward, so that the lead angles and the jacks can be reliably contacted. The arrangement of the components on the breadboard should be determined according to the circuit diagram in order to facilitate the wiring. In order to be able to correctly route and facilitate wire checking, the insertion direction of all ICs must be kept the same, and which cannot be inserted upside down for the convenience of temporary wiring or to shorten the length of the wire.
3) According to the sequence of the signal flow, the method of installation and debugging is adopted. After the components are installed, first connect the power cord and the ground wire. In order to check the line conveniently, try to use different colors for the line. For example, the positive power supply generally uses a red wire, the negative power supply uses the blue, the ground wire uses the black, and the signal wire uses the yellow. Other colors can also be selected according to the real conditions.
4) The breadboard should use a single-strand wire with a diameter of about 0.6mm. Cut the wire according to the distance of the wire and the length of the jack. The wire end is required to be cut into a 45º, and the stripped length of the wire end is about 6mm. All the wires are required to be inserted into the bottom plate to ensure good contact. In addition, bare wires should not be exposed to prevent disconnection with other wires.
5) The connection is required to be tightly attached to the breadboard to avoid collision and ejection of the breadboard, resulting in poor contact. The wiring must pass around the integrated circuit, and it is not allowed to cross the integrated circuit, and the wires must not be overlapped with each other, try to be horizontal and vertical. This is conducive to line wiring and checking, and components replacement.
6) It is best to connect a capacitor with a capacity of tens of microfarads in parallel between the input terminal of each power supply and the ground, so as to reduce the impact of current during transients. In order to suppress the high-frequency components in the power supply, a high-frequency decoupling capacitor should be connected in parallel at both ends of the capacitor, generally 0.01~0.047Uf.
7) During the wiring process, it is required to place the various components on the corresponding position on the breadboard and mark the pin numbers used on the circuit diagram to ensure the smooth progress of debugging and troubleshooting.
8) All ground wires must be connected together to form a common reference point.

Get the full content details from How to Use A Breadboard for Beginners?
Andrewen 20 august 2021, 8:12

A dog is one of the most popular pets that people keep all over the world. The overwhelming majority of them tend to give dogs all they can. Keepers want their dogs to have totally comfortable lives, so they buy comfortable clothes, great toys, and the best rated dog food for their pets. Why does it happen exactly that way?

According to the research data available in different sources online, more and more families and lonely people decide to have dogs nowadays. What is the deal? How can you explain that? Maybe, people just feel better together with their beloved pets? That seems to be true. However, there are other reasons for a person to get a dog and, of course, keep it. Here below, you can find the best and most important reasons to have a dog nearby.

Before we proceed, though, it is important to note that the particular breed of a dog does not matter much here. You can choose the breed according to your preferences and criteria and still be confident that the factors below apply.

Walking with a Dog is Cool

Regular walking down the streets familiar to you can become much more exciting when your beloved dog is walking beside you. In addition, your wellbeing and physical shape receive a significant boost.

Why so? That is simple. Dog keepers just have to spend 30 minutes outside twice a day. That is the time when you exercise and breathe fresh air every day. A dog owner is forced to make walking their routine, so the new routine element improves their health a lot.

Dogs Help People Make Friends

Think about that. Many people decide to get and keep a dog due to the same simple reason: they are lonely. The point is, their loneliness is not acceptable for them, so such dog owners want to meet new people and make friends. Is it a problem?

It is not if you have a dog! As it was already mentioned, you need to walk with your dog in the evening without excuses. So, simply go to a local park in the evening together, and it will not be a challenge for you to make new contacts there.

Your Dog is Surely Your Friend

That is another reason for people to keep their pets with love and get top rated dog foods for them. People and even families can feel lonely not only when they feel it difficult to make new connections. The lack of trust is a completely different factor preventing them from having a friend or two.

When speaking of a dog, you can always be sure that its happy face when it sees you is entirely sincere. Your dog is absolutely satisfied to have such a good and kind keeper. Humans are social creatures who need love. Your dog’s love can add a lot of positivity to your regular days. It will make you smile much more frequently than you used to do before getting a pet!

A Dog is an Effective and Free Antidepressant

You can relax and have fun easily while playing with your dog. At least, your routine responsibilities and activities will get out of your mind during that pet play session. That is extremely useful, especially regarding the crazy tempo of modern reality that does not allow people to relax at all.

Additionally, a dog can be your antidepressant or at least an effective mental healthcare assistant. Psychotherapists working with people who suffer from depression recommend their patients to spend more time with pets, such as cats or dogs. It is proven by science that playing with their beloved animals can increase the level of the “happiness hormone” (serotonin) in human blood. Why shouldn’t you use that effect to make your life brighter?

A Dog Cultivates Responsibility

Families deciding to get a dog frequently assume that their kids will become more responsible if there will be a pet in their house. However, that is only one part of the truth.

The other one is that the dog can cultivate responsibility not only in children. Adults become more self-confident and responsible when they own a dog, too. The point is, you can’t avoid caring about your dog, and that fact alone adds you a lot of mental and spiritual discipline.

To Conclude

If you are thinking about getting a dog for yourself or your children, you’ll have to take a bunch of connected responsibilities. However, a pet will give you a lot in return: friendship, love, faith, and the reason to go in for self-improvement.

Do you still have doubts?

Come on. Just go and get that dog already!

P.S. Don’t forget to visit gnc pet vitamins to find out more about high-quality food for your pet. It deserves the best you can give!
ethanhayes752 12 august 2021, 8:38

What is Hard Drive?
Hard disk, hard disk drive (HDD), hard disk, or fixed disk is the most important storage device of computer. It is composed of one or more aluminum or glass discs. These discs are covered with ferromagnetic material. Your documents, pictures, music, videos, programs, application preferences, and operating system represent digital content all can be stored on a hard drive.
Most hard drives are permanently sealed and fixed in the hard drive. Early hard disk storage media was replaceable, but today's hard disk is a fixed storage medium, which is sealed in a case. With the development, removable hard disks have also appeared, and they are becoming more and more popular with different types. In addition, most of the hard disks installed on microcomputers are called Winchester hard drive.
hard disk drive

Hard Drive Tech Parameters
1) HD Capacity
Capacity is the most important parameter of the hard disk. The capacity of the hard disk is measured in megabytes (MB) or gigabytes (GB). However, the hard disk manufacturer usually takes 1G=1000MB in the nominal hard disk capacity, so the capacity we see in the BIOS or when formatting the hard disk will be smaller than the manufacturer’s nominal value.
The hard disk capacity index also includes the single-disk capacity. It refers to the capacity of a single disk of a hard disk. The larger the single disk capacity, the lower the unit cost and the shorter the average access time. For users, the capacity of the hard disk is like the computer memory, and it will never be too much.
2) Rotational Speed
Rotational speed, or spindle speed is the rotation speed of the motor spindle in the hard disk, which is the maximum number of revolutions that the hard disk platter can complete in one minute. It is one of the important parameters indicating the grade of the hard disk. It is one of the key factors that determine the internal transmission rate of the hard disk, and directly affects the speed of the hard disk to a large extent. The faster the rotation speed of the hard disk, the faster the hard disk can find files. The hard disk speed is expressed in revolutions per minute, and the unit is expressed as RPM(revolutions per minute). The larger the RPM value, the faster the internal transfer rate, the shorter the access time, and the better the overall performance of the hard drive.
The spindle motor of the HDD makes the platters to rotate at a high speed, generating buoyancy to make the head float above the platters. Bring the sector of the data to be accessed below the head, the faster the speed, the shorter the waiting time. Therefore, the rotational speed largely determines the read speed of the hard disk.
The rotation speed of ordinary hard disks for household use is generally 5400rpm and 7200rpm. High-speed hard disks are the first choice for desktop users. For notebook users, it is mainly 4200rpm and 5400rpm. Although some companies have released 7200rpm notebook hard disks, they are still rare in the market. Users have the highest requirements on server for hard disk performance. The speed of SCSI hard disks used in servers is basically 10000rpm, and even 15000rpm. The performance is much higher than that of household products.
A higher speed can shorten the average seek time and actual read and write time of the hard disk. However, as the speed of the hard disk continues to increase, it also brings negative effects such as temperature rise, heavy motor spindle wear, and great operating noise. The speed of notebook hard disks is lower than that of desktop hard disks, which is affected to a certain extent by this factor. The internal space of the notebook is small, and the size of the notebook hard disk (2.5 inches) is also designed to be smaller than that of the desktop hard disk (3.5 inches). The temperature rise caused by the increase in speed puts higher requirements on the heat dissipation performance of the notebook itself. In addition, the noise becomes larger, it is necessary to take noise reduction measures, so more technique requirements on the notebook hard disk productions. At the same time, the increase in speed, while the others remain unchanged, means that the power consumption of the motor will increase, the more electricity is consumed per unit time, and the working time of the battery is shortened, so that the portability of the notebook will be affected. Therefore, notebook hard drives generally use a relatively low-speed 4200rpm hard drive.
3) Access Time
The average access time refers to the time required for the head to reach the target track position from the starting position and find the data sector to be read and written on the target track.
The average access time reflects the read and write speed of the hard disk, which includes the seek time and waiting time of the hard disk, that is, average access time = average seek time + average waiting time.
The average seek time of the hard disk refers to the time required for the head of the hard disk to move to the specified track on the disk surface. This time is of course as small as possible. The average seek time is usually between 8ms and 12ms, while a SCSI HDD should be less than or equal to 8ms.
The waiting time of the hard disk, also known as the Latency, refers to the time that the magnetic head is already in the track to be accessed and waiting for the sector to be accessed to rotate below the head. The average waiting time is half of the time required for the disc to rotate one round, and should generally be less than 4ms.
4) Data Transfer Rate
Data transfer rate refers to the speed at which the hard disk reads and writes data, in megabytes per second (MB/s). It includes internal data transfer rate and external data transfer rate.
The internal transfer rate is also known as the sustained transfer rate, which reflects the performance of the hard disk buffer when it is not in use. The internal transfer rate mainly depends on the rotation speed of the hard disk.
The external transfer rate is also called the burst data transfer rate or the interface transfer rate. It is nominally the data transfer rate between the system bus and the hard disk buffer. The type of hard disk interface is related to the size of the hard disk cache.
The maximum external transfer rate of the Fast ATA interface HD is 16.6MB/s, while the Ultra ATA interface hard disk reaches 33.3MB/s.
The hard disk using SATA (Serial ATA) port is also called serial hard disk. Serial ATA adopts a serial connection method. The serial ATA bus uses an embedded clock signal and has a stronger error correction capability. Compared with the past, its biggest difference is that it can check the transmission instructions (not just data). Errors are found to be automatically corrected, which greatly improves the reliability of data transmission. The serial interface also has the advantages of simple structure and support for hot swapping.
5) Cache Memory
Cache memory is a memory chip on the hard disk controller with extremely fast access speed. It is a buffer between the internal storage of the hard disk and the external interface. Since the internal data transfer speed of the hard disk is different from the transfer speed of the external interface, the cache plays a role as a buffer among them. The size and speed of the cache is an important factor directly related to the transmission speed of the hard disk, which can greatly improve the overall performance of the hard disk. When the hard disk accesses fragmented data, data needs to be continuously exchanged between the hard disk and the memory. With a large cache, the fragmented data can be temporarily stored in the cache, reducing the load on the external system and improving the data transmission speed.

Hard Drive Classifications
1) Mechanical Hard Disk (HDD)
Mechanical hard disk (HDD) is a traditional hard disk, one of the main storage media for computers. It is composed of one or more magnetic discs made of aluminum or glass, magnetic heads, rotating shafts, control motors, head controllers, data converters, interfaces and caches. When working, the head is suspended on a high-speed rotating disc to read and write data. Mechanical hard disk is a computer storage device that integrates precision machinery, microelectronic circuits, and electromagnetic conversion.
2) Solid State Drive (SSD)
A solid state drive (SSD) is an array storage composed of multiple flash memory chips plus a main control and cache, and belongs to a hard drive made of an array of solid electronic storage chips. Compared with a mechanical hard disk, the read speed is faster and the seek time is shorter, which can speed up the operating system startup speed and the software startup speed.
3) Solid State Hybrid Drive (SSHD)
Solid state hybrid drive is a combination of mechanical hard disk and solid-state hard disk. It uses small-capacity flash memory particles to store commonly used files. Disk is the most important storage medium. Flash memory only serves as a buffer to reduce seek time and improve efficiency.

Hard Disk Structure
The hard disk is one of the most important storage for computers. Most of the software needed for the computer to function properly is stored on the hard drive. Because the storage capacity of hard disk is large, it is different from computer memory and optical disk. Hard disks are storage devices based on hard rotating disks used on computers. It stores and retrieves digital data on a flat magnetic surface.
hard drive structure
1) Magnetoresistive Heads (MR heads)
The magnetoresistive head is the most expensive part of the hard disk, and it is also the most important and critical part of the HD technology. The traditional magnetic head is an electromagnetic induction magnetic head that combines reading and writing. However, the reading and writing of hard disks are two completely different operations to limit the hard disk design. The MR head uses a separate head structure: the write head still uses the traditional magnetic induction head (MR head cannot write), and the read head uses a new type of MR head. In this way, during the design, the different characteristics of the two can be optimized separately to obtain the best read/write performance. In addition, the MR head gets the signal amplitude through changes in resistance rather than changes in current, so it is very sensitive to signal changes, and the accuracy of reading data is correspondingly improved. Further more, because the read signal amplitude has nothing to do with the track width, the HD track can be made very narrow, thereby increasing the density of the disc. In addition, GMR heads (Giant Magnetoresistive heads) made of materials with a multi-layer structure and better magnetoresistive effect have gradually become popular.
2) Magnetic Track
When the disk rotates, if the head is held in one position, each head will draw a circular track on the surface of the disk, called tracks. They are invisible to the naked eye at all, because they are only some magnetized areas on the disk surface that are magnetized in a special way, and the information on the disk is stored along such tracks. Adjacent tracks are not close to each other. This is because when the magnetization units are too close, the magnetism will affect each other, and at the same time it will also cause difficulties for the magnetic head to read and write. For example, a 1.44MB 3.5-inch floppy disk has 80 tracks on one side, and the track density on the hard disk is much greater than this value, usually there are thousands of tracks on one side.
The surface of the disk is coated with a magnetic medium used for recording, which are magnetic particles under the microscope. The polarity of tiny magnetic particles can be quickly changed by the magnetic head, and can be maintained stably after the change. The system distinguishes 0 or 1 in the binary system through changes in magnetic flux and magnetoresistance. It is precisely because all operations are performed under microscopic conditions, so if the hard disk is operated at high speed while being shocked by external forces, it may cause irreversible data loss due to the head slaps on the surface of the disk. In addition, the uniaxial anisotropy and volume of the magnetic particles will obviously affect the thermal stability of the magnetic particles, and the thermal stability determines the stability of the magnetic particle, that is, the correctness and stability of the stored data. However, it cannot be increased blindly, because it is limited by the write field that the magnetic head can provide and the signal-to-noise ratio of the medium.
3) Fan
Each track on the disk is equally divided into several arc segments, which are the sectors of the disk. Each sector can store 512 bytes of info. The hard disk drive reads and writes data to the disk from the sectors.
4) Cylinder
A hard disk is usually composed of a set of overlapping disks. Each disk surface is divided into an equal number of tracks, and numbered from the "0" on the outer edge. The tracks with the same number form a cylinder. The number of cylinders on a disk is equal to the number of tracks on a disk. Since each disk surface has its own head, the number of disk surfaces is equal to the total number of heads. The so-called CHS of the hard disk, namely Cylinder, Head, Sector. So when the number of CHS of the hard disk is known, the capacity of the hard disk can be determined. The capacity of the hard disk is the number of cylinders and the number of sectors.

How Does Hard Disk Work?
When the hard disk is working, never turn off the power forcibly, which will cause physical damage to the hard disk and data loss. In addition, with high-speed components in the hard disk, if the high-speed disk is shut down forcibly and suddenly, which is more likely to cause damage to the hard disk. So don't turn on the computer immediately after shutting down. This requires time buffering.
When the hard disk is working, try to avoid its vibration, because the distance between the magnetic head and the magnetic disk is very close. If it is subjected to severe vibration, the magnetic head will hit the magnetic disk to damage it, which will make the entire hard drive unusable.
In the process of using the hard disk, many users compress files to reduce the use of disk space. This will cause the compressed volume file to continue to grow. The data access speed also slowed down, and the number of reads and writes increased, which would affect the heat generation and stability of the hard disk, even reduce service life.

Hard Drive Maintenance
The impact of dust on the hard disk is not small. If dust is attracted to the circuit board, it will cause unstable operation of the hard disk or damage to internal parts. The functional working status of the hard disk has a great relationship with the temperature. Too high or too low temperature will cause the clock frequency of the crystal oscillator to change, which will cause the circuit components to malfunction. In addition, if the temperature is too low, it will cause the air moisture condenses on the component, causing a short circuit.
Second, we need to clear your hard drive regularly. This will increase the speed of your hard drive. If there are too many junk files on the hard disk, the speed will slow down and the tracks may be damaged. However, clean up frequently will also reduce the service life of the hard drive.
Finally, it is anti-virus. Viruses are the biggest threat to the files stored on the hard drive. Therefore, once we found that the virus should be cleared up in time and try not to format the hard disk.

Using Tips
1) Don't shut down suddenly while working.
When the hard disk starts to work, it is generally in high-speed rotation, if we suddenly turn off the power in the middle, it may cause violent friction between the head and the platter to damage the hard disk. Therefore, it is necessary to avoid this. When shutting down, you must pay attention to whether the hard disk indicator on the panel is still flashing, only the indicator stops flashing and then hard disk read and write ends, you can turn off the computer.
2) Prevent dust from entering.
Dust can cause great damage to the hard disk. This is because in a severely dusty environment, the hard disk can easily attract dust particles in the air, causing them to accumulate on the internal circuit components of the hard disk for a long time, which will affect the heat of the electronic components, causing the temperature of the circuit components to rise, and resulting in leakage or burnout of the components.
In addition, dust may also absorb moisture, corrode the electronic circuits inside the hard disk, and cause some invisible problems. Therefore, although the volume of dust is small, the harm to the hard disk cannot be underestimated. Therefore, it is necessary to maintain environmental sanitation and reduce the humidity and dust content in the air. In addition, users cannot remove the hard disk cover by themselves, otherwise the dust in the air will enter the hard disk and scratch the platters or heads during read and write operations.
3) Temperature Control
As we all known, temperature affects the service life of the hard disk. A certain amount of heat is generated when the hard disk is working, so there is a heat dissipation problem during use. 20~25℃ is better. Temperature can also cause failure of hard disk circuit components, and magnetic media can also cause recording errors due to thermal expansion.On one hand, when the humidity is too high, the surface of the electronic components may absorb a layer of water, oxidizing and corroding the electronic circuits, resulting in poor contact or even short circuits, and it will also cause the magnetic force of the magnetic medium to change, causing data reading and writing errors. On the other hand, it is easy to accumulate a large amount of static charge generated by the rotation of the machine in low temperature, which will burn out the CMOS circuit, attract dust and damage the head and scratch the disk. In addition, try not to make the hard disk close to strong magnetic fields, such as loud speakers, motors, radios, mobile phones, etc., so as to prevent the data recorded on the hard disk from being damaged due to magnetization.

Hard Drive Faults
1) HD Cooling Fan
Considering the heat dissipation effect, many people install hard drive cooling fans for their computer hard drives. However, some low-end fans have obvious vibrations and can transmit vibration to the hard drive. In the long term, it will definitely affect the life of the hard drive.
2) Optical Drive
The reading speed of mainstream optical drives has reached more than 50 times speed. When the optical disc rotates at a high speed, the vibration of the optical drive itself will drive the resonance of the chassis, which affects the work of the hard disk. And this kind of high-speed rotation generates a lot of heat, because the optical drive is so close to the hard drive, the heat released from the optical drive will surely increase the temperature of the hard drive.
3) Static Electricity
In the process of repairing the computer, many people hold the hard disk with their hands, but in dry weather, tens of thousands of volts of static electricity may accumulate on the hands of people, which may break down the chips on the circuit board, causing the hard disk to malfunction.
4) Formatting
If the computer hard disk has bad sectors, many users will take formatting measures. In fact, low format damages the hard disk greatly. It may cause the proliferation of bad sectors on the disk, and even cause the loss of hard disk parameters, making the hard disk unable to use.
5) Power Supply
A low-quality computer will cause the hard drive to be disturbed by voltage fluctuations, especially when the hard drive is reading and writing. If there is a problem with the power supply, a hard drive can be scrapped in an instant.
6) Magnetic Field
Because the hard disk is a device that relies on magnetic media to record data, if it is interfered by the magnetic field of the external environment, it is likely to cause the loss of disk data, so you should try to stay away from the magnetic field environment.

Types of Hard Disk Interfaces
There are five categories of hard disk interfaces: IDE, SATA, SCSI, SAS, FC
1) IDE
IDE (Integrated Drive Electronics), refers to the hard disk drive that integrates the controller and the disk body, and is a hard disk transmission interface. There is another name called ATA (advanced technology attachment).
SATA (Serial ATA) hard disk is called serial hard disk based on its serial data transmission method. In the process of data transmission, the data line and the signal line are used independently, and the transmission clock frequency remains independent. Therefore, compared with the previous PATA, the transmission rate of SATA can reach 30 times that of parallel. It can be said that SATA technology is not an improvement of PATA technology in a simple sense, but a new bus architecture.
SCSI (small computer system interface) invention is mainly because the hard disk speed of the original IDE interface is too slow. In fact, SCSI is not designed specifically for hard drives, in fact it is a bus-type interface, working independently of the system bus.
4) SAS
SAS (serial attached SCSI) is serial attached SCSI, which is a new generation of SCSI technology. Like the popular SATA hard disks, it uses serial technology to achieve higher transmission speeds, and improves internal space by shortening the cable. It is a brand new interface developed after the parallel SCSI interface, which is designed to improve the performance, availability, and expandability of the storage system, and provide compatibility with SATA hard drives.
SAS interface tech can be backward compatible with SATA. Specifically, the compatibility of the two is mainly reflected in the compatibility of the physical layer and the protocol layer.
5) FC (Fibre Channel)
Just like the SCIS interface, FC is not an interface technology designed and developed for hard disks at first. It is specially designed for network systems. However, as storage systems require high speed, they are gradually applied to hard disk systems. FC hard disk was developed to improve the speed and flexibility of multi-disk storage system. Its appearance greatly improves the communication speed of multi-disk system, and it uses optical cable connections between systems in a point-to-point (or switching) configuration. There are something to note: the hard disk itself does not have an FC interface, where the cabinet has, which is interconnected with an optical fiber switch.

Can a Computer Run without a Hard Drive?
A computer can still function without a hard drive. This can be done through a network, USB, CD, or DVD. Computers can be booted over a network, through a USB drive, or even off of a CD or DVD. When you attempt to run a computer without a hard drive, you will often be asked for a boot device.

Should I buy SSD or HDD?
1) According to data read and write speed
A computer with the same configuration can reach a read and write speed of about 500M/S with a solid state drive, but about 150MB/S with a mechanical hard drive. The difference is nearly three times the speed, which makes the difference in computer response speed even greater.
2) According to data security and shock resistance
Since the mechanical hard disk reads and writes data through the magnetic head to read the disk, it is easy to cause data damage due to the collision of the disk and the magnetic head during high-speed rotation, especially it is in the handling process that the disc may be damaged, so everyone needs to be extremely careful when touching it.
3) According to weight and volume
Compared with mechanical hard disks, solid state drives are smaller and lighter in appearance, and has stronger performance and faster transfer speed than mechanical hard drives.
4) According to noise and heat dissipation
Since the solid state drive is made of flash memory particles, it is not equipped with mechanical parts and flash memory chips, and there is no disk and head mechanical motors, fans, etc., so that it can ensure absolute silence. The heat is also very small, and the heat dissipation is also very fast.
5) According to power consumption
SSDs commonly use less power and result in longer battery life because data access is much faster and the device is idle more often. With their spinning disks, HDDs require more power when they start up than SSDs. For example, the general full-speed power consumption of a 3.5-inch mechanical hard disk is about 12W, and a 2.5-inch hard disk is only about 5W. The full-speed power consumption of the solid-state drive is about 10W, its working power is generally 2-3W, less than 1W in standby mode.
Although solid state drives are definitely faster than mechanical hard drives from above mentioned, but it doesn’t mean that solid state drives are necessarily better than mechanical hard drives, because in terms of price and capacity, mechanical hard drives are "T" is the unit, and most of the solid-state drives are still in G. Although there are also "T", the price is beyond everyone's expectations. One more thing to note is that it is more difficult to restore data if the solid state drive is damaged, while the mechanical hard drive can restore data through repair. Therefore, in terms of data security, mechanical hard drives have more advantages in storing important data. In short, consider comprehensively according to the actual situations.

What the Defferences between HDD and SSD?
A hard disk drive (HDD) is a traditional storage device that uses mechanical platters and a moving read/write head to access data. A solid state drive (SSD) is a newer, faster type of device that stores data on instantly-accessible memory chips.
Generally, SSDs are more durable than HDDs in extreme and harsh environments because they don't have moving parts such as actuator arms. SSDs can withstand accidental drops and other shocks, vibration, extreme temperatures, and magnetic fields better than HDDs.
SSDs commonly use less power and result in longer battery life because data access is much faster and the device is idle more often. With their spinning disks, HDDs require more power when they start up than SSDs. However, when not in use, magnetic drives are more reliable for long-term storage than flash memory ones. Thus, HDDs are more capable of long time storage than SSDs when powered off.
While normal HDDs can last about 10 years max in reality, and an SSD lifespan has a built-in time of death. To keep it simple: an electric effect results in the fact that data can only be written on a storage cell inside the chips between approximately 3,000 and 100,000 times during its lifetime.
As for price, SSDs are more expensive than hard drives in terms of dollar per gigabyte. A 1TB internal 2.5-inch hard drive costs between $40 and $60, but as of this writing, the very cheapest SSDs of the same capacity and form factor start at around $100.
With their ruggedness and low energy consumption, SSDs are becoming more popular with portable PCs. With all the advantages that SSD has over HDD, price, availability and capacity are probably the primary factors constraining the acceptance of this new technology.

What is the Lifespan of a Hard Drive?
Though the average might be three to five years, hard drives can theoretically last much longer (or shorter, for that matter). If a hard drive works 24 hours continuously, it will be damaged in less than 3 years. After normal use, there should be no problem for 5 or 10 years. During use, the garbage must be cleaned regularly and kept HD cool, so as not to get stuck.
As with most things, if you take care of your hard drive, it will better last to its potential.

How Much Do Hard Drives Cost?
A 1TB internal 2.5-inch hard drive costs between $40 and $60, but as of this writing, the very cheapest SSDs of the same capacity and form factor start at around $100. That translates into 4 to 6 cents per gigabyte for the hard drive versus 10 cents per gigabyte for the SSD.
According to market trend, the number of hard drives sold each year has declined recently due to the migration of consumer PCs to SSDs, and also demand for higher-capacity HDDs by exascale datacenters. When demand for HDDs spikes, retailers sell out quickly, and prices increase as dealers come into play.

What are the Best Hard Drives?
Best Hard Drives at a Glance
Seagate BarraCuda
Toshiba X300
WD VelociRaptor
WD Blue Desktop
Seagate Firecuda Desktop
Seagate IronWolf NAS
Seagate FireCuda Mobile
WD My Book
G-Technology G-Drive
Andrewen 11 august 2021, 6:02

The following is a list of common diode types and symbols:

A diode is an electronic device made of semiconductor materials (silicon, selenium, germanium, etc.). It has unidirectional conductivity, that is, when a forward voltage is applied to the anode and cathode of it, the diode is turned on. When a reverse voltage is applied to the anode and cathode, the diode is turned off. Therefore, the diode is equivalent to a switch.

Junction field-effect transistor (JFET) not only has the advantages of small size, light weight, low power consumption, and long life of bipolar transistors, but also has the characteristics of high input resistance, good thermal stability, strong radiation resistance, low noise, etc. Its manufacturing process is simple and it is easy to integrate. Therefore, it has been widely used in large-scale and very large-scale integrated circuits. According to the structure and working principle, field effect transistors(FETs) can be divided into two categories: Junction field effect transistors (JFET) And insulated gate field effect transistor (IGFET).

Light-emitting diodes (LED) are commonly used light-emitting devices that emit energy through the recombination of electrons and holes to emit light. They are widely used in the field of lighting. LED can efficiently convert electrical energy into light energy, and have a wide range of uses in modern society, such as lighting, flat panel displays, and medical devices.

The photodiode is a sensor device that converts light signals into electrical signals. The photodiode works under the action of reverse voltage. When there is no light, the reverse current is extremely weak, called dark current. When there is light, the reverse current rapidly increases to tens of microamperes, called photocurrent. The greater the intensity of light, the greater the reverse current. The change of light causes the current of the photodiode to change, which can convert the light signal into an electrical signal.

A PNP transistor is a bipolar junction transistor made by one n-type material is doped with two p-type materials. It is used to source current, in other words, it is controlled by the current. In a PNP transistor, the majority charge carriers are holes.

A NPN transistor is a bipolar junction transistor made by one p-type material is doped with two n-type materials. It uses both electrons and electron holes as charge carriers, and the majority charge carriers are electrons.

Zener diode uses its PN junction reverse breakdown state, its current can be changed in a wide range while the voltage is basically unchanged. It is mainly used as a voltage regulator or voltage reference component.

Varistor diodes, also known as "voltage-dependent resistor (VDR)", are made by using the characteristic that the junction capacitance changes with the applied voltage when the PN junction is reverse biased. When the reverse bias voltage increases, the junction capacitance decreases, on the contrary, the junction capacitance increases. The capacitance of the it is generally small, and its maximum value is tens of pF to hundreds of pF, and the ratio of the maximum capacitance to the minimum capacitance is about 5: 1. It is mainly used for automatic tuning, frequency modulation, and equalization in high-frequency circuits, for example, as a variable capacitor in the tuning loop of a television receiver.

Bridge rectifier is the most commonly used device for rectification using its unique unidirectional conductivity, and is often used to convert alternating current to direct current.
A tunnel diode or Esaki diode that can be switched at a high speed, which can reach the range of microwave frequencies. The principle is to use the quantum mechanical effect. It is a crystal diode with tunnel effect current as the main current component.

Switching diodes are a type of semiconductor diodes, which are specially designed and manufactured for "on" and "off" on the circuit. The turn-on time required for it is shorter than that of ordinary diodes. The common series are 2AK, 2DK and others, which are mainly used in electronic computers, pulse and switch circuits.

The rectifier diode is a semiconductor device that converts AC power into DC power. Usually it contains a PN junction with two terminals, anode and cathode, and is a vital component in power supplies where they are used to convert AC voltage to DC voltage.

The Schottky diode, also called Schottky barrier diode or hot-carrier diode, are used for their low turn-on voltage, fast recovery time and low-loss energy at higher frequencies. When it is in unbiased condition, the electrons lying on the semiconductor side have a very low energy level compared to the electrons present in the metal.

A laser diode, injection laser diode, or diode laser is similar to a LED in which a diode pumped directly with electrical current can create lasing conditions at the diode's junction. It includes single heterojunction (SH), double heterojunction (DH) and quantum well (QW) laser diodes.

A silicon controlled rectifier (SCR) or semiconductor controlled rectifier, also known as the thyristor, is a four-layer solid-state current-controlling device, NPNP or PNPN. When a gate pulse is applied to it, just like a diode. SCRs are unidirectional devices as opposed to TRIACs.
Andrewen 30 july 2021, 9:12
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