Knowledge of Electronic Components

Electronic components in different devices in the model and logo are not the same, in the correct distinction between different at the same time, but also to understand all their functions, this article will be from the three aspects of electronic components simple science and technology, - practical knowledge of electronic components

I. Voltage, current

Voltage and current are brothers, current flows from a place where the voltage (level) is high to a place where the voltage (level) is low, current must be generated because of the presence of voltage, but the presence of voltage does not necessarily generate current - if only voltage is present and no current, it can be proven that there is a break in the circuit (eg there is a switch in the circuit). If there is only voltage but no current, this is evidence of an open circuit (eg a switch in the circuit). In addition, sometimes the voltage measurement is normal, but the current measurement is not necessarily normal, such as a slight short-circuit phenomenon or the resistance value component of a large phenomenon, etc., so in maintenance, it must be combined with the voltage value and current value to be analyzed. When testing an unknown voltage or current with a multimeter, make sure you shift the gear to the highest gear, eg measure the value and then gradually lower the gear. The symbol for voltage is "V" and the symbol for current is "A".

II. Resistors

Different materials present a certain resistance to the current passing through them, and this resistance is called resistance, and an entity (element) that has this physical property of aggregate resistance is called a resistor (simply a conductor with a resistance value). Its role in the circuit is very important, for computer boards and peripherals, the number is also very large.

Its classification also differs if it is classified by use: current limiting resistors, buck resistors, voltage divider resistors, protective resistors, trigger resistors, sampling resistors, decoupling resistors, signal attenuation resistors, etc.; if classified by shape and manufacturing materials: gold layer resistors, carbon layer resistors, cement resistors, non-inductive resistors, thermistors, varistors, pull-up resistors, chip resistors, etc.; if categorized by power: 1/ 16W, 1/8W, 1/4W, 1/2W, 1W...... and so on.

These resistors are ordinary resistors, so we need to know their resistance value of the nominal method, as an example, I will take the computer host card on the most common chip resistors (other resistors of the nominal method are the same): Chip resistor nominal method digital and color ring method of the two.

First, the digital method, usually there are three resistors on the XXX number, the first two numbers are the number of tens and digits, the last number is 10 X-th power, the specific resistance value of the resistor is the first two numbers of the two-digit number multiplied by 10 X-th ohm power, for example, indicated by resistance 104 is 100,000 ohms (i.e. 100 kΩ), indicated by resistance value 473 is 47,000 ohms (i.e., 47 kΩ); the following author to say a few words about the color ring method, this nominal method is the most common in all resistor nominal method (the shape of the patch has relatively little), the common color ring usually has four rings, we will gold or silver ring as the last ring, the first three rings colors correspond to the corresponding number, we know the number of numbers we need to use the number of the above method of reading its resistance value, but first we need to know what color represents what number, so we need to remember such a mnemonic - black, brown, red, orange, yellow, green, blue, purple, gray and white, which corresponds to 0123456789 for gold and silver, respectively 10-1 and 10-2, the two colors in the four-color ring resistor are just marked with an error value, if you understand the line. I also give two examples below for illustration, for understanding and remembering, for example, the resistance of the marked brown, black, yellow and silver ring resistor is 100,000 ohms (ie 100 KΩ), the marked resistance of the yellow, purple, orange and gold ring resistor is 47,000 ohms (ie 47 kΩ). JoinWin is a professional distributor of electronic components and cooperates with original manufacturers, provides original integrated circuits and connectors, supplies hard-to-find and discontinued parts. To get accurate data for millions of electronic components. Enjoy affordable prices for quality products.

There is also a five-color ring resistor, this resistor is some relatively small resistance values, relatively high precision resistors, because there are applications in computer peripherals, so I also introduce: it is gold or silver for the penultimate ring, the first three color ring were hundreds, tenths, digits and the last color circle is the error value, the specific resistance value of such resistance is the first three-color circle name of three digits of three numbers composed of three digits multiplied by 10 negative 1 times or negative 2 times Ohm as indicated by brown, purple, green, silver and brown by a ring with a resistor resistance value of 1.75 Ω.

There is so much about some resistor basics, only when replacing the resistor, it should also be noted that usually 1/4 or 1/8 of the resistor to replace the chip resistor is not a problem. When using the digital method, the chip resistor is usually black, the resistor in the circuit symbol for "R".

III. Capacitors

In addition to resistors, capacitors are the most common, simply put, capacitors are containers that store electric charge. Most hardware people may know about the shape of the capacitor, so I'll just say it briefly. Common capacitors can be divided into: chip capacitors, tantalum electrolytic capacitors, aluminum electrolytic capacitors, OS fixed capacitors, electrodeless electrolytic capacitors, porcelain capacitors, mica capacitors, polypropylene capacitors according to the shape and manufacturing materials.

One of the chip capacitors in the computer mainframe within the various boards on the most common, but only a small number of chip capacitors have a logo, have a logo of the method of reading the capacity of the chip capacitor and chip resistors, only the unit symbol for pF (1000000pF = 1μF), because for most of the chip capacitors, why most of them do not have a logo, I think the damage may not be easy. There are a lot of ceramic capacitors and various metallized capacitors in the computer's power case and color display and many peripherals, so I would also like to say that such capacitors are among non-polarized capacitors. Their capacity nominal method and digital resistors, only some capacitors will use "n", "n" means 1000 and is placed in the position, and the capacitance value also has a relationship, such as the nominal capacity of 10n capacitor is 10000pF (ie 0.01μF), marked as 4n7 capacitor capacitance is 4700pF (ie 4.7n) rather than 47000pF because two kinds of capacitor voltage withstand are marked on the capacitor like 1005V, 400V ...... and so on (only a few don't mark but mostly above 65V). usually above 65V).

Here I want to tell you about aluminum electrolytic capacitors, which are characterized by large capacity and low price, so they are widely used in various boards and power supply boxes, as well as most peripherals. In order to reduce production costs, some manufacturers use very relatively low withstand voltage values ​​of capacitors, such as 6.5V filter capacitors for 5V withstand voltage. It can be used, but the failure rate is slightly higher, combined with its thermal stability is not very high, therefore the replacement of aluminum electrolytic capacitors is very frequent. Only when replacing the voltage withstand in the actual voltage 1.5 times more than on the capacitor, but also pay attention to the positive and negative poles can not be connected to the reverse, especially the power part of the electrolytic capacitors should pay more attention to these two points, otherwise the capacitor may burst .

In addition, there is a brand of capacitors, different brands of resistance simply do not have the same  error value, but different brands of capacitors have different service life and quality, such as different losses and insulation resistance and temperature coefficients are different. The following author will introduce you to some good brands: PHILIPS (Philips), Ruby con BLACK GATE (black gold steel), Ruby con (Ruby), ELNA, ROE, SOLEN, Nichicon, DECON, WIMA (this product is very expensive capacitors above 1μF capacity), RIFA , ERO if you really don't know it. You really do not recognize the words, just remember that you do not buy all the capacitors on C, D two-letter (all prefixes) capacitors, such capacitors are not the world's leading manufacturers, and even some capacitors used in computer boards and cards can also cause bad influence. These capacitors can only be used for the capacity requirements of the power are not very high in the product (for example, up to 4 dollars per radio), its capacity and some other performance indicators on the error are very large, although the new factory products can ensure that 4 years or so can have better performance so it can't be uploaded to computer accessories.