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Component-based

Materials commonly used in electronic products manufacturing industry can be divided into the production of materials and auxiliary materials, two categories, the production of materials can be divided into: electronic components, standard parts, hardware parts, plastic parts; auxiliary materials can be divided into: tags, silicone grease, plate washer water, alcohol, heat-shrinkable tubes, tin section (line) and so on.

Electronic Components

As electronic technology and its applications, the rapid development of components used in an increasing number, study and master the performance of commonly used components, uses, quality and discrimination method, the assembly of electrical equipment to improve the quality and reliability will play an important guarantee for effect. Resistors, capacitors, inductors, diodes, transistors, integrated circuits and other devices are commonly used in electronic circuits.

Section resistor

Resistor is larger resistivity material (carbon or nickel-chromium alloy, etc.) are made. It plays a current-limiting circuit, sub-pressure role.

First, the classification of resistor

Resistors in electronic products is essential, the use of most components. It is varied, the common are the following categories.

1, according to resistance can regulate hours

With fixed resistors, variable resistors two broad categories.

The fixed resistor is the resistance of the resistor can not be adjusted; variable resistor is the resistance within a certain range of adjustable resistor, such as potentiometers.

2, according to material of sub -

There wirewound resistors, non-wirewound resistors.

3, according to zoning

There are general-purpose, high-impedance type, high-pressure type, high-frequency non-sense type.

In addition to these three kinds of classification, there are the shape and pinout according to the structure classification.

Second, some resistors and graphic symbols shape

1, resistor shape:

2, graphic symbols:

Third, the main technical parameters of resistors

Nominal resistance, allowing the error and rated power are fixed resistors of the main parameters. Some resistance standard resistor values, this is the nominal resistance value of resistor. Nominal resistance value and its actual value is often not fully consistent with the actual value and the nominal value of the difference between the percentage obtained by dividing the nominal value is the resistance of the error, which reflects the degree of precision resistors. The following table shows common error of resistor rating.

Tolerances

㊣ 0.5% ㊣ 1% ㊣ 2%

㊣ 5% ㊣ 10% ㊣ 20%

Level

0050102

i j k

Type

Precision

Normal

Rated power is the resistor can withstand long hours working under the maximum power. Rated power larger resistors, generally will be rated directly printed on the resistor. Rated power smaller resistor can be from its geometric dimensions and surface area on the see the following table:

Dimensions

Rated

Carbon Film Resistor

Metal Film Resistors

L D

L

D

0.06W

8

2.5

0.125W

12

2.5

7

2.2

0.25W

15

4.5

8

2.6

0.5W

25

4.5

10.8

4.2

1W

28

6

13

6.6

2W

46

8

18.5

8.6

Fourth, the main technical parameters of resistors on methods of marking

Resistor of nominal resistance and errors are usually marked on the resistor, there are several methods of marking.

1, straight standard method

Direct standard method is to use numbers and text symbols marked directly on the resistor symbol of the main parameters method, as shown in Figure 1-1, the resistance value of 5.1K次, error of ㊣ 5%. If the resistor does not mark the error, then both ㊣ 20%.

2, text symbols France

Sign method is written in figures and text symbol or a combination of both a regular in the resistor symbol on methods of marking out the main parameters. Specific methods as follows: resistance of the integer part of the resistance unit of signs and symbols written on the front of the fractional part of the resistance unit of signs and symbols written on the back of resistance, as shown in Figure 1-2, resistance to 4.7K次.

5.1K次 ㊣ 5% 4K7

Figure 1-1 Figure 1-2

Signs and symbols are as follows:

Ohm (1 ohm), with 次 that the cases of: 0.1次 logo 次1

1000 Europe (103 ohms), with K, said cases of: 1K次 marked as 1K

Megohm (106 ohms), with M said that the cases of: 2.2M logo 2M2

Gigabit Europe (109 ohms), with G said that the cases of: 5.6 ℅ 109 mark for the 5G6

Trillion megohm (1012 ohms), with T said that cases of: 4.7 ℅ 1012 logo 4T7

3, color standard method

Color standard method is based on the color of the provisions of the resistor main parameters on the signs on methods of marking. Parameters specified in the table below:

Color

Digits

Multiplier

Permissible error%

Brown

1

101

㊣ 1

Red

2

102

㊣ 2

Orange

3

103

Yellow

4

104

Green

5

105

㊣ 0.5

Blue

6

106

㊣ 0.25

Purple

7

107

㊣ 0.1

Gray

8

108

White

9

109

Black

0

100

Silver

10-2

㊣ 10

Gold

10-1

㊣ 5

Example: Ring resistors, shown in Figure 1-3, the resistor's nominal resistance of 2K, to allow a tolerance of ㊣ 5%.

Wuhuan resistance, shown in Figure 1-4, the nominal resistance of the resistor is 2.4K, allowing error is ㊣ 1%.

4, the digital representation

The digital representation is a resistor with a nominal value of the digital expression of three methods of marking. Digital from left to right, first, 2 for the RMS and the third for the multiplier, that is, the number of zero, the unit of 次. Error usually written symbols J (㊣ 5%), K (㊣ 10%), said.

Figure 1-5 Figure 1-6

Example: Figure 1-5, the nominal resistance of the resistor is 2.2K, allow the margin of error of ㊣ 5%.

Figure 1-6, the resistor's nominal resistance of 10K, to allow error ㊣ 10%.

5, resistor distinguish good and bad

Visual can be seen that lead break or burn resistors and other surface fault; with multimeter ohms file or other special test equipment can test the internal resistors is a good and resistance are normal.

Section Capacitor

I. Classification of capacitor

1, according to changes in capacitance can sub -

Fixed and variable type two main categories

2, according to media sub -

Air-dielectric capacitor, oil-filled capacitors and solid media (mica, paper, refer, ceramic, film, etc.) capacitors.

3, according to polar sub -

Polarity of capacitors and non-polar capacitor

Second, some capacitors shape and graphic symbols

1, capacitor shape

2, graphic symbols:

Third, the main technical parameters of capacitors

Nominal capacity, allowable error, rated voltage, insulation resistance, leakage current, dissipation factor and the time constant capacitors are the main technical parameters.

1, capacitor nominal capacity and the permissible error of the basic meaning of the same as with the resistor. The basic unit of capacitance F (Farah), that is 1V voltage capacitor can store one coulomb of electricity for its capacity shall 1F. With F treated as a unit in the application is often too much, so often used millifarad (mF), microfarad (米F), sodium Act (nF) and leather Act (pF). The relationship is as follows:

1F = 103mF

1mF = 103米F

1米F = 103nF

1nF = 103pF

2, rated voltage

Rated voltage is usually referred to as pressure, refers to permissible ambient temperature range, the capacitance to work long hours imposed by the maximum voltage RMS. Capacitor rated voltage usually refers to the dc voltage.

3, insulation resistance and leakage current

Capacitor dielectric can not be absolutely non-conductive, when the capacitor with DC voltage, the capacitor will Youlou currents. If the leakage current is too large capacitor will heat damage. In addition to electrolytic capacitors, the other capacitor leakage current is very small, so that with the insulation resistance of the insulation performance parameters; while electrolytic capacitors due to leakage large, so that with the leakage current of the insulation performance (and capacity is proportional to).

4, loss factor

Capacitor dissipation factor means the power loss and reactive power loss ratio. Usually the role of capacitance in the electric field, its storage or transmission will be a part of the energy and the polarization due to the role of media leakage into unwanted heat, this part of the heating energy consumption is the capacitance of the loss, obviously the greater the loss, fever, and the more seriously.

4, capacitor parameters on methods of marking

The nominal capacitor capacity and allow the error is marked on the capacitor on its methodology can be divided into the following.

1, straight standard method

Direct standard method is the nominal capacitor capacity and allow the error directly on the signs marked on the capacitor method. Shown in Figure 2-1, CXJD for the model, 2200米F nominal capacity, ㊣ 10% to allow for error, 02.5 for production time.

2, text symbols France

Integral part of the nominal capacity is usually written in terms of volume units of signs and symbols in front of the fractional part of the written in terms of volume units of signs behind the symbols. If 3.3米F labeled 3米3, 2.2pF marked as 2p2.

3, the digital representation

Capacitors and resistors digital representation of the same. However, capacitors in the digital representation of its units of pF. If 0.1米F marked as 104.

Fourth, the use of capacitors

Capacitor's basic function is to store charge, its electrical and electronic circuits used in a very wide range, mainly used with the AC-coupled, isolated DC, filtering, bypass and the selection of AC or pulse frequency and so on. Figure 6-3 The next capacitor C is a common filter capacitor, the following in order to figure 6-2 (b) waveform diagram to illustrate the working process of filtering capacitor. When u in the first half of a rise, began to charge capacitor C; while u in the first one and a half weeks of decline, capacitor C discharges through the load RL; in the second half weeks, the capacitor has also taken a charge - discharge process, so capacitive loop repeated. The discharge curve shown in Figure 6-2 (b) as shown in dotted lines.

From Figure 6-2 (b) can be seen by the output capacitor filtered a number of smooth curves, to a certain load, the greater the capacitance, the output curve of the more smooth.

Section Inductors

Also known as inductance coil inductor is made of the use of electromagnetic induction principle, and played in the circuit inductor choke, transformer, transmission signal and so on.

First, the classification of Inductors

Many different types of inductors, but not the same classification criteria, usually by the changes in inductance is divided into a fixed inductors, variable inductors, tuning inductors, etc.; according to the core nature of the inductor coil can be divided into air-core inductors, core inductor, copper inductors, etc.; according to wound characteristics can be divided into single-layer inductors, multilayer inductors, inductors and other hive.

Second, some inductors shape and graphic symbols

1, inductor shape

2, inductor graphic symbols

Third, the main technical parameters of inductors

1, inductance L

Inductance L is also known as self-inductance, is said inductor self-sensing capabilities of a physical quantity. When the magnetic flux through a coil changes, the coil will be formed in electric potential, which is the phenomenon of electromagnetic induction. The electric potential generated by said induction electric potential, electric potential is proportional to the size of the rate of change in magnetic flux and coil turns. The basic unit of inductance for the H (Hang), the actual should be there are still millihenry (mH), micro-Hang (米H), the conversion relations are as follows: 1H = 103 mh = 106米H.

2, reactance XL

Inductive reactance parameter table in the inductor are generally finding out, but it is with the inductance, quality factor Q and other parameters are closely related, due to self-inductance of the coil inductance is always potential to prevent coil current changes, so the coil to the alternating current resistance in the role of Size XL will use inductive resistance, said. XL and the coil inductance L and the AC frequency ƒ is proportional to the calculation formula: XL = 2羽ƒL. (Where XL units 次, ƒ unit HZ, L units of H) is not difficult to see that low-frequency current through the coil when the XL is small, through the DC when the XL is zero, this time played only a DC resistance of the coil resistance effects (inductance coil The DC resistance is very small, may be similar to short-circuit). XL high-frequency electric current through a great, if L is also large, can be regarded as open.

3, quality factor

, Also known as quality factor Q value or merit, that is, the coil in a certain frequency AC voltage to work and the equivalent loss of resistance when the reactance ratio.

4, DC resistance

Namely, the DC electrical resistance of their own feelings of the coil can be used multimeter measured directly.

5, rated current

Inductor to work long hours that allows the maximum inductor DC current value.

4, inductor sign method

Inductor symbol of methods and resistors, capacitors sign the same way, with straight standard method, text symbols France and color standard method.

Fixed inductors commonly used in the past few color codes Indications Act, referred to as color-coded inductors. At present, China produced some of the fixed inductors method uses color-coded signs, and some are marked directly on the inductor value, that is, direct standard method. In a number of electronic machines, such as television sets, extensive use of a fixed inductor. It is the copper wire wrapped around the core on. And then re-use epoxy resin or plastic package together, this inductor is characterized by small size, light weight, solid structure, easy to use.

IV Transformers

The two coils close together, when a coil line, the current changes, the magnetic flux through the other coil corresponding changes will occur, so that the coils appear in EMF, and this is the phenomenon of mutual inductance. Transformer is made according to principles of mutual inductance.

First, the classification of transformer

Transformer coupling between the material according to the coil points, empty core transformers, magnetic core transformer, iron core transformers.

According to the operating frequency points, there are high-frequency transformers, intermediate frequency transformers, low frequency transformers, pulse transformer. If the radio magnetic antenna, which is the high-frequency transformer; in the radio IF amplifier stage, using a medium frequency transformer, commonly known as "the Week"; wider variety of low-frequency transformer, a power transformer, input transformer, etc.; TV line output transformer, also known as "ignition coil", which is a pulse transformer.

2, transformers graphic symbols

Third, the main technical parameters of transformers

Transformer ratio, rated power, temperature, efficiency, no-load current, insulation resistance are the main technical parameters of the transformer.

1, transformer ratio n

Transformer ratio n is the transformer primary voltage of U1 and U2 of the ratio of secondary voltage, or primary coil turns N1 and N2, the ratio of secondary coil turns. The beginning of secondary coil turns and voltage have the following relationship:

The voltage and current transformers have the following relationship:

Where I1 is the primary winding current; I2 for the secondary winding current

The number of turns and current transformers have the following relationship:

Type in the last three when n> 1 when compared with step-down transformer, the other hand, compared with step-up transformer. n = 1 is usually used as isolation transformers.

2, rated power P

Refers to the specified frequency and voltage of the transformer can work long hours and not exceeding the prescribed temperature rise of the output power. Rated power capacity of the unit with the VA (volt-ampere) said.

3, temperature

Refers to work at full capacity transformer coil temperature rise after the stable value and the temperature difference between the work environment, affect the temperature rise of transformer insulating performance one of the reasons.

4, efficiency 灰

Means the transformer output power and input power ratio. Namely, where the output power PO for the transformer, PI for the transformer input power. Because there is loss in the circuit reasons, the efficiency of the transformer is always less than 100%.

5, no-load current

Secondary load of zero (open circuit), the junior still have a current, this part of the current is called the no-load current.

6, insulation resistance

The transformer windings, the windings and core insulation between is not ideal. When the applied voltage, it will Youlou currents exist, this is because the transformer insulation resistance due to the existence. Insulation resistance greater the smaller the leakage current; transformer insulation resistance is too low, may make live instruments and equipment, chassis, resulting in pairs of instruments, equipment or physical danger.

Fourth, the use of transformer

Transform the voltage transformer in the circuit, the current transformation, transmission power, impedance matching, or impedance transformation purposes, the following is only a brief voltage change and impedance matching.

1, the voltage conversion

Usually we take the power of the coil called the primary coil or primary side coil to produce induced under the action of the mutual inductance of the coil, said electric potential force for secondary coil or vice-edge coil, a transformer generally only one

A primary coil, but the secondary coil may have one or more. Left early, are a secondary coil, N1 for

The primary coil turns, N2 as the secondary coil turns, RL load; U1 AC voltage for the primary coil, U2

Inductive voltage generated by the secondary coil, then, can be seen, secondary voltage and primary coil

Inverse relationship between the number of turns. That N1> N2 time, U2

U2> U1, which is a step-up transformer. If the transformer has more than one secondary coil, each secondary coil and the

The primary coil turns may be different than both, so a step-up transformer can coexist and step-down possible.

2, impedance matching

In electronic circuits, the signal source and load impedance mismatch, the need to use matching components or circuits inserted in between the two in order to achieve impedance matching, transformer impedance transformation function can play a role in this. Such as the left shows, the transformer secondary coil load RL, the equivalent load impedance secondary coil from the transformer A, B depends on

Into the equivalent impedance RL ', the equivalent impedance RL' with the transformer ratio, the load relationship: RL '= n2 ℅ RL.

V Relay

Relays are commonly used in automatic control circuit of electronic components, it is to use a smaller current to control the large current automatic switch, automatic operation in the circuit play, auto-regulation, security protection and so on.

First, the classification of relay

Many different types of relays commonly used are electromagnetic and dry spring type, usually relays are divided into DC, AC, Reed and time relay of four.

2, the main technical parameters

A rated voltage or rated for operating current

This refers to the relay coil normal working hours required voltage or current value.

2, pull-in voltage or current

Means the relay pull-in movement can produce a minimum voltage or current. Under normal circumstances, pull-in voltage for the rated voltage of 75% or so.

3, the release of voltage or current

Reduce the voltage across the relay coil to a certain value, the relay from the pull-in state transitions to the release of the state.

4, contact load

Refers to contact of the load capacity. Such as the relay contact load is DC28V/10A or AC220V/5A, it is said that such a relay contact at work voltage and current values should not exceed the value, otherwise it would contact damage.

Third, reed relays

Reed full name "dry reed switch," is determined by two pieces of magnetic conductive material also made of reed-ping

OK to inclose filled with inert gas (such as nitrogen, helium, etc.) glass

Tube composed of switching elements, overlap and form a certain gap to form access

Points, left the dry reed pipe shape diagram.

Reed works as follows: When a permanent magnet near the reed switch or from around the dry reed pipe formed after the magnetic field coil power so reed magnetization, the reed-contact part of the magnetic sensors were out of the opposite polarity magnetic pole , as shown below, different names poles attract each other, when the magnetic force to attract more than the elastic reed, the contact will be pull-in; when the magnetic force is reduced to a certain value, the contact will be elastic reed bounce.

Reed has the following advantages and disadvantages:

K isolated from contact with the atmosphere inside the glass tubes filled with another inert gas, thus greatly reducing the contact in the open and close the course due to sparks caused by contact contact oxidation and carbonization. And to prevent the outside world of organic vapor and dust and other impurities on contact erosion.

L reed thin and short, have a higher natural frequency, increased contact of the on-off speed, the switching speed faster than the average of the electromagnetic relay 5 to 10 times

M small size and light weight.

N The disadvantage is the switching capacity of small, contact is easy to produce large jitter, as well as contact contact resistance.

VI diode

To truly understand diodes, you must first understand what is the semiconductor. Conductivity between the material between the conductors and insulators, known as semiconductors. For example, germanium (Ge-32), silicon (Si-14), selenium (Se-34) and metal oxides. Silicon or germanium and other semiconductor materials are made of single crystal, its atomic arrangement becomes a very neat crystal structure, such a pure single-crystal semiconductor known as intrinsic semiconductors. Intrinsic Semiconductor Although there are two kinds of free electron and hole carriers, but because of the number of very small, the conductivity remains low. If the intrinsic incorporation of trace impurities in semiconductors, its conductivity will be greatly enhanced. As the incorporation of different impurities, such doped semiconductors can be divided into N-type and P-type semiconductor

Body of two main categories:

One is in the silicon or germanium crystals by mixing a small amount of pentavalent elements such as phosphorus (P-15), the number of free electrons in semiconductors is much larger than the number of holes, that is, free electrons become "majority-carrier." The holes become a "minority-carrier." This means that in order to free electron conductive impurity semiconductor-based, so called N-type (electronic type) semiconductors.

The other is silicon or germanium crystals in the mixed small amounts of trivalent elements, such as boron (B-5), the number of holes in semiconductors is much larger than the number of electrons, that hole to become the "majority-carrier." Electronic become a "minority-carrier." This means that the main impurities in semiconductors in order to hole conduction, so called P-type (hole type) semiconductor.

In an integrated chip, the doping process with different side of the crystal formation of P-type semiconductor, the other side of the formation of N-type semiconductor, then the junction will be formed between the two PN junction. Constitutes PN junction diodes, transistors, FET and so on the basis of semiconductor devices. When the PN junction forward voltage across Canada (ie, P then the power supply positive side, N side then the negative terminal of power supply), this time showing PN junction resistance is very low, the forward current is big (PN junction in the conduction state); as PN junction reverse voltage across Canada (ie, P then the power supply negative side, N side then the power supply positive), this time showing a high resistance of PN junction reverse current is weak (PN junction in a cut-off state), that is, PN one-way junction conductivity

Diode is a PN junction, together with lead, contact electrodes and control constitute the shell. Here we have a simple introduction to a variety of diodes.

First, the classification of diodes

1, according to zoning

There rectifier diodes, zener diode, detector diode, light-emitting diodes, switching diodes, photodiodes, and so on.

2, according to material of sub -

There germanium diodes, silicon diodes, gallium arsenide diode.

3, according to manufacturing process sub -

Little contact with two kinds of diodes and diode surface contact.

4, according to works sub -

There varactor diodes, avalanche diodes, zener diodes and so on.

Second, some diodes shape and graphic symbols

1, diode shape

2, diode graphic symbols

3, rectifier diode

1 volt-ampere characteristics: refers to the voltage across the diode increases with the current flowing through the diode curve, this curve can be divided into forward and reverse characteristic features two parts. As shown in Figure 6-1

Figure 6-1 Figure 6-2

Forward Features

When the diode forward voltage plus, there was a positive current flows through. But the forward voltage is very low, the external electric field is not able to overcome the electric field for the majority of PN junction carrier diffusion resistance movement formed, this time a positive current is small, diodes show great resistance. When the forward voltage exceeds a certain value (silicon tube of about 0.5V, germanium tube about 0.3), the diode resistance becomes very small, the current increased rapidly. This voltage is often said that the valve dead-zone voltage or voltage.

Reverse characteristics

Diodes with reverse voltage, due to minority carrier drift movement, the formation of a small reverse current, reverse current has two characteristics: First, the increase with temperature increased rapidly; the second is the reverse voltage does not exceed a certain range, the reverse current does not change with reverse voltage to reach saturation, so the current IBO called the reverse saturation current. When the voltage across the diode increases to reach a certain value, a sharp increase in reverse current diode loss of one-way electrical conductivity, a phenomenon known as electrical breakdown, the voltage is called the reverse breakdown voltage. Diode due to electrical breakdown caused by pipe damage is permanent.

2, the main parameters

Maximum rectifier current IOM

Maximum diode rectifier current is able to allow the maximum average current value is positive. When the current exceeds the permitted value, the diode will overheat and burn.

URB reverse breakdown voltage and maximum reverse voltage URM

URB is the diode reverse breakdown voltage when the value of its reverse current surge in post-breakdown diode one-way conductive been destroyed. Manuals are usually given on the work of URM maximum reverse voltage of reverse breakdown voltage is about half or two thirds, in order to ensure the safe operation of diodes.

Maximum reverse current IRM

IRM refers to the diode plus its maximum reverse voltage and reverse current values. IRM smaller, then the better conductivity of one-way pipe.

3, the application of diode rectifier

The use of diodes will be alternating one-way conductive pulsating direct current is converted to a one-way circuit, known as the rectifier circuit, as shown in Figure 6-3. At this time of the diode can be seen as switching elements, namely, the so-called ideal diode.

Figure 6-3

Vice-side transformer-based AC voltage: u (t) = Usin肋t where U is the RMS transformer secondary side voltage waveform shown in Figure 6-2 (a) as shown in 肋t = 0 ~ 羽 during the period, u is positive and a half weeks transformer on the secondary side of the polarity of the positive under the negative, that is, a point the potential is higher than b points, therefore, diodes D1 and D3 conduction, D2 and D4 deadline, when the load resistor RL get a half-wave voltage; at 肋t = 羽 ~ 2羽 period, u is in the negative half-cycle, the polarity of transformer secondary side for the next positive on the negative, that is, b points, the potential is higher than a point, diodes D2 and D4 conduction, D1 and D3 cut-off, in the RL get another half-wave voltage, and in two and a half weeks, the current flowing through R direction is the same. Thus, when the supply voltage alternating one week, in the RL get the size of the pulse voltage: U0 = 0.9U, the waveform shown in Figure 6-2 (b) below.

4, Zener Diodes

Regulator pipe is a special kind of surface-contact type semiconductor silicon diode in the circuit because it can stabilize the voltage effect, it is said that regulators, voltage regulator tubes in the circuit of the role of the dashed part in Figure 6-3. Its shape is similar with ordinary diodes, but the volt-ampere characteristics are different from ordinary diode reverse characteristics is that it is very steep, as shown in Figure 6-4. Regulator pipe is working in reverse breakdown area, when the reverse voltage breakdown voltage changes within the UZ, the reverse current is very weak, when the reverse voltage increases to the breakdown voltage of UZ, the voltage regulator tube reverse breakdown, reverse current will abruptly increase, since although a large within the framework of current changes, but the voltage regulator tube at both ends of very few changes, take advantage of this characteristic Zener voltage regulator in the circuit play a role, but stable pressure tubes and diodes in general different from its reverse breakdown is reversible, that is, remove the reverse voltage, the voltage regulator tube has returned to normal, but if the reverse current exceed the allowable range of Zener breakdown occurs Heat damage.

Figure 6-4 Figure 7-1 Figure 7-2

5, light-emitting diodes

Light-emitting diode is used such as gallium phosphide or gallium arsenide phosphorus semiconductor material, and to direct the energy into light-emitting devices. As also from the ordinary PN diode structure into the same electrical conductivity with a one-way, but with its light-emitting diode is not one-way electrical conductivity, but rather it directs light (display) devices. Light-emitting diodes with low power consumption, small size, fast response, anti-vibration, long life and other advantages of widely used light and so on.

Light-emitting diodes can be made of materials of other light color, packaging such as form and shape into many types of light-emitting diodes shape shown above. At present, more commonly used is the round, square and other light-emitting tube, LED color to red, green, yellow and other color-based, some of which could give two or three kinds of colored light-emitting tube.

Right-handed light-emitting diodes basic application circuit as shown. U as an electrical

Source voltage, R limit resistor, I is the current flowing through the light-emitting diode.

Light-emitting diodes for forward current drive devices, flow through the light-emitting diodes

Current must not exceed the limits allowed by the tube, or light-emitting diodes will be destroyed.

6, transient voltage suppressor (TVS tube)

Transient Voltage Suppressor often referred to as lightning tube, is a security device. This device in the circuit system to play streaming clamping effect can be effectively reduced due to lightning, circuit switching-off generated when the high-voltage pulse, to avoid the lightning, high-voltage pulse damage to other devices.

Transient voltage suppression diodes are one-way, two-way two kinds. One-way graphic symbols and voltage regulator tube is similar to left for the bi-directional transient voltage suppression diode graphic symbols and

Application circuit. When the input pulse into a high-voltage surges, regardless of whether the direction of how the pulse, TVS tube can quickly enter the breakdown state, the input voltage clamp.

The following table shows the Division I bi-directional TVS tube commonly used parameters:

Model

Cut-off voltage

(V)

Breakdown Voltage

(Vmin)

Breakdown voltage (Vmax)

Test Current (mA)

Maximum clamping voltage (V)

The maximum pulse current (A)

Reverse leakage current (uA)

P6KE6.8CA

5.8

6.45

7.14

10

10.5

58.1

1000

P6KE12CA

10.2

11.40

12.6

1

16.7

35.3

5

P6KE22CA

18.8

20.90

23.10

1

30.6

19.9

5

7, Schottky diodes

Schottky diode is a metal and semiconductor manufacturing process using planar form, it exists in only one carrier (electron) transfer charge, and therefore there is no minority carrier storage effect. Therefore, it has the reverse-recovery time is short (7ns) and positive pressure drop (0.4V) of the outstanding advantages, which is mainly used for switching power supply rectifier and the inverter so as freewheeling diode.

8, fast recovery diode

Fast Recovery Diode works like an ordinary diode, but also guide the use of a single PN junction, but a different manufacturing processes and ordinary diode. It is the proliferation of the depth and layers can be precisely controlled at the extension. Is thus eligible for the higher switching speed. Meanwhile, pressure within the allowable range, a thin epitaxial layer could have been done. It is the reverse recovery time is fast recovery diode important parameter, is defined by a forward current through 0:00 into reverse, then reverse converting from low-value to the required time interval. And Schottky diode compared to the much higher pressure, the main power supply is also used in the inverter to do rectification components to reduce the turn-off losses, improve efficiency and reduce noise.

VII transistor

What we usually refer transistor refers to amplification of signals or switch roles, with three electrodes of semiconductor devices, which have a three-story house semiconductors, are known as the launching area, the base area and the collector area, the internal structure shown in Figure 7 -1. The important feature of the transistor with a current control, and this is due to transistor within the current distribution relationship between the established, namely, IC = 汕IB and IE = IC + IB. That is, IC primarily by the size of the IB decision, IB determines the size of the change in proportion to changes in the IC, so transistor is a current control device. We use the current control effect transistor to achieve the amplification of the signal amplitude and energy conversion, we must make it work in the output characteristics of the enlarged area, that is, firing junction forward biased, collector junction reverse bias, shown in Figure 7 -2 is an NPN common-emitter amplifier tube, VCC, Rb, and fired junction transistor circuit together constitute the base, so that emission knot in a positive skew; RC for the collector resistor, VCC, RC and transistor collector junction - launching a common junction constitute the collector loop. Another important role of the RC as the base for most inputs, it will change in collector current into the collector voltage change as the output signal. C1, C2 as the coupling capacitors, with isolated DC, passing the role of the exchange.

First, the classification of transistor

Transistor according to the operating frequency points, there are high-frequency and low-frequency transistor transistor; according to the size of divided-power high-power, medium power and low power transistor; according to package the form of points, metal packaging and plastic packaging; of different electrode divided by PNP and NPN transistor. PNP and NPN transistor the outer map and graphic symbols following figure:

Second, transistor output characteristic curve of

Transistor output characteristic curve is used to indicate that the tube voltage and current of the interrelationship between, it reflects the performance of transistors is an important basis for analysis of amplification circuits, left for the most common-emitter connected in the output when the characteristic curve.

According to the characteristics of the output characteristic curve, usually triode scope of work is divided into three regions: cut-off zone, saturated zone, enlarged area, and their respective characteristics are summarized as follows:

A cut-off area

Output characteristic curve of IB = 0 of this area under the curve known as the cut-off area, this time launching junction with the collector junction reverse bias are at. Because there through transistor current ICEO, the collector current has not really closed. In terms of silicon tube, UBE <0.5V when the cut-off, germanium tube UBE <0.1V when the cut-off. When the transistor work in the end zone, it is usually the ideal way that the collector and the emitter is equivalent to a switch between the off-state.

2, saturated zone

In the UCE <1V within the framework of the corresponding characteristic curves approximate straight up area, called the saturated zone, the value of the transistor saturation UCE is called saturation voltage drop, with UCES said low-power silicon tube of about 0.3V, germanium tube of about 0.1V. Transistor working in saturation, the collector junction with the launch are at the forward biased junction, showing low resistance state, and therefore a larger current, equivalent to a switch connected to the state.

3, enlarged area

Launch junction transistor forward biased collector junction reverse bias, this time transistor to amplify the work of the regional district, transistors work in the larger zone IC with IB increases in proportion to increase them for the characterization of the the relationship between the value, when the UCE constant, IC and IB of the ratio of total emitter transistor quiescent current amplification factor to symbols, that is, it referred to as the DC amplification factor. Since the output characteristic curve near the close spacing of the smaller, IB increases, the curve spacing is also larger, so the value also change. This also leads to dynamic current amplification factor 汕, it refers to the UCE at the same value, the collector current variation → IC and base current variation → IB ratio, ie, 汕, also known as the exchange of amplification factor. Although the meaning of the different 汕, but little difference between the two values, so often do not make a sharp distinction between.

Third, the main parameters of transistor

1, the current amplification factor 汕

Transistor current amplification factor is an important parameter, with regard to its definition, out in front of a presentation are not repeated here.

2, reverse saturation current ICBO

It refers to the collector of the minority carrier in the collector junction reverse-bias drift formed under the action of reverse current. It is with the diode reverse saturation current is essentially the same, so when the emitter open (IE = 0), the collector current value shall be the reverse saturation current. ICBO size is one of the hallmarks of good or bad quality of the tube, ICBO small as possible. Low-power tube is about a few microamps, this value is small but very affected by temperature, is working transistor, one of the main factors of instability.

3, through current ICEO

It refers to the base open circuit (IB = 0), the collector and the emitter between the reverse current. ICEO size of ICBO 汕-fold. ICEO affected by temperature more serious, so it has a greater impact triode's work.

Section VIII-FET

FET is the use of the electric field effect to control the current changes in the amplification components. It is compared with the transistor has a high input impedance, low noise, and good thermal stability, and thus rapid development and application. FET amplifier with the transistor with the pieces, but it works different: Transistor is a current control device, under certain conditions, the collector current is controlled by the base current, while the FET is a voltage-controlled device, the electronic current is affected by the gate voltage control.

The type of FET can be divided into two categories: one category is JFET, one is insulated gate type FET, also known as metal - oxide - semiconductor insulated gate type FET, referred to as MOS tube. Semiconductor transistors are PNP type and NPN type; channel FET used in accordance with its semiconductor material, and the other is divided into P-type and N-channel two kinds. Channel is the current channel.

1, JFET

N-channel JFET the matrix is an N-type silicon material, for N-channel. From the matrix leads to two electrodes are called source (S) and drain (D). In the matrix attached to a small piece on each side of P-type materials, called the gate electrode leads to (G). Thus, in the channel and gate formed between the two PN junction, when the gate opens, the channel is equivalent to a resistor, whose resistance tubes of different models vary, generally about several hundred to 1000 Europe is not Europe and so on.

The upper photo JFET structure diagram and graphic symbols. One gate with an arrow, the arrow points to channel namely, N-channel JFET, the arrow departure from the channel for the P-channel JFET.

2, insulated-gate FET

Insulated Gate FET is characterized by a high input resistance, easy made of integrated circuits. Its internal structure and graphic symbols are as follows:

In an N-type silicon, there are two in close proximity in high concentrations, P-proliferation area, source and drain, respectively, in the source area and drain regions between the silicon wafer, a layer of insulating silicon dioxide insulation layer covered with aluminum, which is the gate. Between the gate and other electrodes are insulated, so called insulated-gate FET. As the source, gate oxide layer between the layer, such tubes are basically no gate current, so input impedance is very high.

IX Optocoupler

Optical coupler is a combination of semiconductor optoelectronic devices, by the light-emitting device and light receiver consisting of an "electric - Light - electricity" device. When there is input signal type, light emitting device, subject to illumination by the optical device resulting from current output there is signal output, achieved with light-mediated signal transmission. This circuitry allows the input and output terminal non-conductive direct link, there are excellent anti-jamming performance, widely used in electrical isolation, level shifting, inter-stage coupling, switching circuits, pulse coupling circuit.

Common optocoupler to have any type, double row straight rod and other packages. On a common photodiode photo-coupler and the optical-coupler transistor circuit symbol, photoelectric triode optical coupling device as examples the work process: phototransistor of the conduction and cut-off is determined by two of the light-emitting Canadian forward voltage control, when coupled with light-emitting diode forward voltage, the light-emitting diode there is current through the LED, so that the decrease of resistance phototransistor conduction; On the contrary, when the deadline at the light-emitting diodes, light emitting diode no current through the , photosensitive transistor resistance increases and cut-off.

Section X of the insurance component

Commonly used in the insurance component of ordinary glass tube fuse, delayed-type fuse, fuse resistors and temperature fuses, etc., the following brief their respective characteristics:

An ordinary glass tube fuse

This type of insurance is very commonly used component, its low cost, easy to use, and rated current ranges from 0.1A to the dozens of security, size, specification mainly 18mm, 20mm, 22mm.

2, delayed-type fuse

Delayed-type fuse can withstand a short period is characterized by large current (inrush current) the impact, while in the current overload over a certain time limit and can reliably fuse. This fuse is mainly used in large transient current boot of electronic machinery, such as color television sets on the extensive use of delayed-type fuse, its specifications primarily 2A, 3A, 4A and so on. Delayed-type fuse current specifications often preceded by the letters T, such as T2A, which can be distinguished from ordinary fuse.

3, Fusing Resistor

Fusing resistor resistance also known as the insurance is a dual function with resistors and fuse components, although its resistance value is usually small, only a few tenths of Europe and to Europe, a few of dozens of European or 1000 in Europe, mostly from the insurance-limiting resistor effect, so the main function is to play role as insurance. Insurance resistors are mostly gray, colors, numbers, said ring or resistance, power rating, the decision by the resistor size, there are marked directly on the body of the resistance.

4, recoverable fuse

Recoverable fuse is a polymer material and conductive material mixture made of over-current protection components, at room temperature, its resistance is small, but the action will form a high-impedance state, when troubleshooting then automatically return to low resistance state.

Based on the maximum withstand voltage, recoverable fuse can be divided into several series, each series, also based on the different operating current, is divided into a number of models. The following table for a company's WH60-005 restore electrical fuse characteristics:

IH

(A)

IT

(A)

Time-to-Trip Vmax

(V)

Imax

(A)

Rmin

(次)

Rmax

(次)

Itrip (A)

Tmax (S)

0.05

0.10

0.15

≒ 10

60

40

5

12

Electrical characteristics as follows:

IH: Maximum operating current (25 ⊥)

IT: Minimum operating current (25 ⊥)

Itrip: Overload Current

Tmax: maximum operating time overcurrent

Vmax: Maximum Overload Voltage

Imax: Maximum Overload Current

Rmin: Minimum Resistance (25 ⊥)

Rmax: Maximum resistance (25 ⊥)

Time-to-Trip: over-current characteristics of

Left hand recoverable fuse in the circuit usage, when the input voltage is abnormal or load short-circuit current I caused by the sudden increase in the circuit, the recoverable fuse to form high-impedance state after starting to restrict the circuit current in a certain range of sky safety

The role of the protection circuit, such as troubleshooting, the fuse automatically restore the state back to add low resistance, the circuit

Can enter the work.

Section XI Crystal Oscillator

Crystal oscillator is used to stabilize the frequency and select the frequency of electronic components, we often say crystal oscillator (also called crystal), is from the quartz crystal at a certain azimuth cut thin slices, and then the chip 2 the corresponding layer on the surface coated with silver and fitted with a pair of metal pins later sealed enclosure constituted crystal oscillator (see shown left).
Quartz oscillator is based on its chip can do the "piezoelectric effect", that is, the chip between the two plates plus an electric field, will produce mechanical deformation of the chip; back of the, if applied mechanical stress between the plates, will in the corresponding direction to generate the electric field, a phenomenon called the piezoelectric effect. If the plate is added between the alternating voltage, it will produce mechanical deformation vibrations, while mechanical deformation will be produced in an alternating electric field, but the amplitude of mechanical vibration is small, but its vibration frequency is very stable.

Crystal oscillator according to package sub-shape metal shell, glass shell, plastic such as bakelite shell and several, according to frequency stability divided into common type and high-precision two kinds.

The main electrical parameters of the crystal oscillator is the nominal frequency ƒ0, the load capacitance CL, motivation level, operating temperature range and temperature frequency difference. Crystal oscillator circuit composed of elements required to access with an external capacitor, the capacitor that is the load capacitance, load capacitance can check the technical parameters of product too. CL is a part in determining the oscillation frequency, and therefore, under the specified load capacitance of the oscillation frequency of oscillator components, namely, the nominal frequency, the nominal frequency marked on the shell, it is very easy to identify. Incentive level is the effective power consumption of crystal work; temperature frequency difference is within the operating temperature range relative to the base operating frequency of the maximum temperature deviation from the value of this parameter represents the frequency temperature characteristics of crystal.

12th Festival Hall devices

Hall is a Hall-effect device based on the principle of the use of integrated circuits made of. When a pass a current of metal or semiconductor thin vertically placed in a magnetic field, the sheet on both sides of this will produce a potential difference, this phenomenon is called Hall effect. Sheets on both sides called the Hall potential difference generated by electric potential. Hall electric potential and magnetic field strength of the magnetic induction B, slice through the current I is proportional to the thickness d is inversely proportional with the sheet, that is: U = K * B * I / d, K for the Hall coefficient, with sheets material.

Hall devices can be divided by the output function switch type, linear type Hall device; by active types can be divided into bipolar and MOS type.

13th Festival IC

Integrated circuits, is a tiny single-chip, using a number of semiconductor fabrication crystal diode, transistor, and resistors, capacitors and other devices and connect to complete the specific functions of the electronic circuits.

Considerable number of types of integrated circuits, according to their different functions can be divided into analog integrated circuits and digital integrated circuits two broad categories. The former is used to generate, amplification and processing of a variety of analog signals, while the latter used to generate, amplification and processing digital signals. Analog signal is a continuous change in amplitude with time signals; digital signal refers to the time and magnitude of the discrete values of the signal, also known as electrical pulse or pulse signal.

According to the different integration can be divided into small-scale, medium scale, large-scale and ultra large scale integrated circuit four categories. Integration refers to the unit area of the chip contains the number of electronic components. Generally considered: on-chip integration is less than 100 elements or 10 gate integrated circuits called small-scale integrated circuits; integration of 101 ~ 1000 components or 11 to 100 as medium-scale integrated circuit gate; integration in 1001 ~ 100,000 components or 101 ~ 10000 gate circuit is called LSI; integrated more than 100,000 components or circuit known as the 10000 VLSI.

Classification of integrated circuits there are many, such as the manufacturing method according to the structure or process can be divided into semiconductor integrated circuits, film integrated circuits.

The picture shows a common integrated circuit on the outer package, its package in the form of a circular metal packaging, flat ceramic, plastic packaging at the shell, single, double in-line package. Pin 4 feet, 8 feet, 14 feet and so on.

The upper photo was single, dual in-line, and Ling, circular IC pin identification map.

XIV integrated regulator device

First, three-terminal fixed regulator device integration

Three-terminal fixed regulator is the integrated device leads to foot only the following three aspects: input, output, grounding terminal, the output voltage is fixed and can not be adjusted; the device is set within the over-current, chip overheating and adjust the device safe operating area of the protection circuit, so the use of small external components needed to use very convenient.

Integrated three-terminal fixed-output voltage regulator type of the device according to a positive voltage series (78 series) and a negative voltage of series (79 series) two series, each series have 5V, 6V, 8V, 9V, 10V, 12V, 15V , 18V, 24V and many other types of output voltage of each type there 100mA (78L ℅ ℅, or 79L ℅ ℅), 500mA (78M ℅ ℅, or 79M ℅ ℅), 1.5A (78 ℅ ℅ or 79 ℅ ℅) the maximum output current.

Left for the three-terminal fixed voltage regulator integrated naming rules, such as the 78L05 voltage of the output is 5V, maximum load current of 100mA; 7909 for the negative 9V output voltage, maximum load current of 1.5A.

3 solid fixed shape and the integrated regulator device pin identification diagram is as follows:

1, three-terminal fixed parameters of an integrated voltage regulator

Integrated three-terminal fixed regulator parameters to 7805 as examples

Parameters

Test conditions (Tj = 25 ⊥)

Standard Value

Units

Minimum

Typical

Maximum

Output Voltage VO

5.0mA ≒ IO ≒ 1.0A

4.8

5.0

5.2

V

7.0V ≒ VI ≒ 20V

Voltage regulation SV

7.0V ≒ VI ≒ 25V

3

50

mV

Current regulation of SI

5.0mA ≒ IO ≒ 1.5A

15

100

mV

Standby current Iq

4.2

6.0

mA

Output Noise Voltage VNO

10Hz ~ 100Hz

40

200

uV

Ripple rejection ratio Srip

F = 100Hz, 8V ≒ VI ≒ 18V

68

78

dB

Minimum Input - Output pressure | VI-VO |

IO = 1.0A

2.0

2.5

V

Short-circuit output current limit ISC

0.75

1.2

A

Output peak current IOP

1.3

2.2

3.3

A

Output voltage temperature coefficient of ST

㊣ 0.6

mV / ⊥

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