Basic Diode Guide

Diode

1 - Semi-conductors
 
1.1 - What is semiconductor?
Quality semiconductor materials to produce all kinds of semiconductors such as Diode, Transistor, IC, but we have seen in the electronic equipment on this. Semiconductors are substances that have characteristics intermediate between electrical conductors and insulators, in terms of chemistry, the semiconductor is substances have four electrons in the outermost layers of atoms. That is the nature
Germanium (Ge) and Silicium (Si) From the initial semiconductor (pure) one must create two types of transistors are N type semiconductor and semiconductor type P, then assembling pieces of N and P type semiconductor obtained the diode or transistor. Si and Ge has four valence, ie the outer layer is 4. Electronics, in the possible pure Si atoms (Ge) linked together by covalent links as shown below.

Pure semiconductors.

1.2 - N type semiconductor
* When we mix a small amount of substances such as chemotherapy 5 Phospho (P) in nature Si transistor is a P atom linked to four Si atoms in contact plus the chemotherapy, only 4 phosphorus atoms involved electronic link and the remaining one electron and become free electrons => Semiconductor at become redundant electronics (electrically negative) and are called semiconductors N (Negative: negative).

N semiconductors

1 .3 - P type semiconductor

In contrast, when we added a small amount of a third chemotherapy as Indium (In) on Si is a semiconductor material Indium atoms will link with four Si atoms linked by covalent and a missing link e => into holes (positively charged) and the called semiconductors P.

Semiconductor P

 
2 - Diode (diodes) Semiconductors
 
2.1 - Adjoining P - N and the composition of the semiconductor diode. 
There are two semiconductors are P and N, if the coupling of two semiconductors in an adjacent P - N It is a diode, P-N junction is characterized by : At the contact surface, the excess electron diffusion in semiconductors N to the semiconductor region P to fill the holes => form a Ion electrically neutral => domain layer constitutes Ion insulation between two semiconductors.

Termites exposed P - N => Anatomy of the diode.

* The contact form on the relationship P - N and also the structure of a semiconductor diode.

Symbols and shape of a semiconductor diode.

 

2.2 - Polarization upon to diode.
 Have a positive voltage (+) to the anode (P semiconductor regions) and negative voltage (-)
in Katot (semiconductor region N), then the interaction effect of power pressure, shrinking domain insulation, keeping the voltage difference between the two poles meet 0.6 V (with Si diode type) or 0.2 V (with diode type Ge) is the domain analysis insulation reduced to zero => Diode start conducting. If continue to increase the voltage across the diode current increased but the difference
voltage difference between the two poles of the diode does not increase (remained the same at 0.6 V)

Diode (Si) polarization upon - When Dode lead
agreement, the reduce voltage at 0.6 V

Line voltage characteristic of the agreement through the diode

* Conclusion: The diode (type Si) agreement is polarized, if the voltage polarity upon <0.6 V is not
currents through the diode, if the polarization voltage = 0.6 V, the agreement reached with the line passing through Diode current through the diode and then increased rapidly but still keep pressure drop agree at 0.6 V value.

2.3 - Diode for reverse polarity.

When the polarity is opposite to the diode power (+) in Katot (sold Guide N), source (-) to anode (P transistors), the interaction of the voltage contrast, the wider domain insulator and prevents current through contiguous relationship, diode can withstand very large reverse voltage about 1000V, the new diode is punctured.

Diode only fires when the voltage of opposite polarity increases> = 1000V

 

2.4 - Methods of measurement Diode test

Measuring Diode test

Set the clock in the scale x 1Ω, which put two sticks on either end Diode, if: Upon measuring        the anode rod black, red stick on Katot => kim up, reversing the needle does not measure up is =>  Diode good If measured on both clockwise = 0Ω => a diode has been short. If the needle is not        measured positively up => is diode breaks. In measurements on the diode D1 well, diode D2 and     D3   has been short-cuts If the measure to scale back on Diode 1KΩ metal is still a little diode         

detectors.

 

2.5 - Application of Semiconductor Diode.

* Do one-dimensional conductive properties should Diode commonly used in the rectifier AC into a
way, the detector circuit, the circuit to reduce voltage polarity transistor operation the. the rectifier diode can be integrated into a diode bridge of the form.

The diode bridge rectifier ac.

3 - Types of Diode
 
3.1 - Zener Diode
* Components:
Diode Zener diode has a structure similar but usually have two layers of semiconductor P - N coupled together, Zener diode is used in the polarization mode contrast, when polarized upon as diode zener diode normally distributed but inverse zener diode will reduce the voltage to a fixed value recorded on the diode.

Shape Zener diode (DZ)

Symbols and applications of zener diode in the circuit.

The above diagram illustrates the application of DZ, U1 is the power source voltage change, dz is the diode voltage, R1 is to limit the line. We see that the source U1> dz dz shall always fixed on whether U1 source changes. As U1 source changes, the change back through DZ, DZ efflux through a limiting value of about 30mA.  Usually people use source U1> 1.5 => 2 DZ was more fitting term and the R1 so that the most backward through the DZ<30mA.

If U1 <U1 DZ when pressure changes and changes in the DZ
If U1> DZ change when U1 => constant pressure on the DZ.

 

3.2 - Optical Diode Thu. (Photo Diode)
Diode optical receiver operating in reverse polarity mode, with a piece of shell diode glass to the light on the relationship P - N, the current through the diode reverse proportional to light intensity in the diode.

Symbols of Photo Diode

Illustrate the operation of Photo Diode

 
3.3 - emitting diode (Diode Emiting Light: LED)
Diode developed planar light emitting diode being polarized upon, the voltage LED work of about 1.7 => 2.2 V line via Led range from 5mA to 20mA LEDs are used to make light sources, flash design, power status. etc. ...

Emitting diodes LED

 

3.4 - Diode varicap (variable capacity diode)
Content is variable Diode Diode capacitance as a capacitor, and capacitance changes when we change the voltage on the diode reverse order.

Capacity variable diode un of varicap (V D) in the resonant circuit

In the philosophy of regulation when applying VR, the voltage put to the diode reverse varicap changes, changes the capacitance of the diode  => Changes the resonance frequency of the circuit.Variable capacity diode used in the color of television channels, in the circuit to adjust the resonant frequency by voltage.

 

3.5 - Diode pulse
In the power pulse at the output of the pulse transformer, we must use the Diode pulse for rectifiers. pulse diode diode is working at high frequencies of a few tens of KHz, conventional diode rectifier can not replace the positiondiode pulse, whereas pulse diode can replace position regular diode, diode pulses with a higher cost diode is often many times. Characteristics, the diode pulse shape is not any different with Diode often, but usually the next pulse Diode dashed or marked marked by two rounds

The symbol of the diode pulse

 

3.6 - Diode detector.

Diode is a type of glass and small notebooks called diode contacts for contact surface between the semiconductor P - N at a point to avoid power parasitic capacity, diode detector commonly used in high frequency circuits used for signal detection.

 

3.7 - Diode rectifier.

As the diode rectifier to the surface for the 50Hz AC power rectifier , Usually have three types of diode is 1A, 2A and 5A.

5A diode rectifier

Basic Capacitor Guide

Basic Capacitor

Capacitors: Capacitors are passive electronic components widely used in electronic circuits, they are used in the source filter circuit, noise, signal ac circuit, oscillator circuit. Etc. ...
1. Components of the capacitor.
Components of the capacitor consists of two parallel plates, in the middle of an insulating layer called the dielectric.
People often use paper, ceramic, mica, paper impregnated with chemicals as capacitor dielectrics and also classified under the name of the capacitor dielectric as paper, ceramic capacitors, Capacitor



                                                Structure composed of ceramic capacitors

 

2. Actual shape of the capacitor.

The shape of the ceramic capacitors.

The shape of the convergence of

3. Capacitance, units and symbols of the capacitor.
* Capacity: A measure of the ability to speak on two charged plates of the capacitor, the capacitance of the capacitor depends on the area of plates, dielectric material and the distance keeping the two plates by the formula

C = ξ. S / d

• In the C: is the capacitance capacitor units are FARA (F)
• ξ: A dielectric constant of the insulating layer.
• d: the thickness of the insulating layer.
• S: is the area of ​​the capacitor plates.

* Capacitance of the capacitor units: Unit is FARA (F), 1Fara was great in practice so common as the smaller units MicroFara (μF), NanoFara (nF), PicoFara (pF).

• FARA FARA μ 1 = 1,000,000 = 1,000,000,000 = 1,000,000,000,000 n F p F
• 1 μ FARA FARA n = 1000
• 1 n = 1,000 p FARA FARA

* Symbol: Capacitors are denoted as C (capacitor)

Symbols of the capacitor on the principle diagram.

 


4. The charging of the capacitor discharge.
An important property of the capacitor is charging the capacitor discharge characteristics, thanks to the nature of this convergence is likely to lead AC.

Illustration of the nature of the load capacitor discharge.

* Capacitor charging: As the image above we see that, when the switch K1 closed, electric current passing from U to the lamp load capacitor, a charge is made ​​flashing lights, when the load capacitor is fully charged down equal to 0 so the lights off.
* Capacitor discharge: When the capacitor has fully charged, if the open switch K1, K2 switch closed, the current from the positive (+) of the capacitor discharge through the lamp on the negative (-) as flashing lights, when gathering the ball full potential power lights off.
=> If the capacitor capacitance becomes larger, the flashing lights as long or longer charging times larger.
5. How to Read the capacitance value of capacitor.
* As of: The value of the capacitance of the capacitor is recorded directly on the relative convergence
=> Gathering of the capacitors have polarity (-), (+) and are always cylindrical.

Capacitor of 185 μF is the capacitance recording / 320 V

* The paper capacitors, ceramic capacitors: capacitor paper and ceramic capacitors with values ​​written in symbols

Ceramic capacitor values ​​recorded by the symbol.

• How to read: For the first two digits of the 10 ^{(Hat number 3)}
• For example, the right ceramic capacitor 474K image recording means
  Value = 47 x 10 ⁴ = 470,000 p (in units of pico Get FARA)
  FARA = 470 n = 0.47 μF
• K or J at the end is only 5% error or 10% of the capacitor.

* Do read the value of the capacitor.

How to read capacitor values ​​laundry and ceramic capacitors.
Note: The letter K is the error of convergence.
50V is the maximum voltage that capacitor tolerance.

* Paper and ceramic capacitors also have a way to treat others as stated in decimal units and get MicroFara

A record number of capacitors of paper and ceramic capacitors.

6. The idea of the value of capacitor voltage indicated on the body:

• We see that regardless of how well the capacitor voltage values ​​recorded immediately after the capacitance value, this is the maximum voltage value that convergence tolerance, the capacitor voltage will be explosive.
• When inserted into a circuit capacitor voltage is U, then it is never mounted capacitor voltage value of about 1.4 times higher than Max.
• For example, to mount capacitor circuit 12V 16V, 24V circuit must be fitted 35V capacitor. etc. ..

-
7 - Classification of capacitor
7.1) of paper capacitors, ceramic capacitors, mica capacitors. (Capacitors are not polarized)
The convergence of this kind regardless of Yin and Yang and often have small capacitance of 0.47 μF or less, the capacitors are often used in high frequency circuits or circuit noise.

Ceramic capacitor - a capacitor is not polarized.

7.2) magnetized (polarized capacitors)
Convergence of the positive and negative equity, convergence of a larger value and values ​​from 0.47 μF to 4700 μF range, convergence chemical commonly used in low frequency circuits or for power filters, convergence of cylindrical always ..

Convergence of - is a negative-positive polarity.

7.3) rotate.
Capacitors can turn the focus turning to change the capacitance value, capacitor is usually mounted in the radio to change the resonant frequency when you tune.

Capacitors used in radio rotation

8 - Method of test capacitors
8.1) Measurement of test paper and ceramic capacitors.
Paper capacitors and ceramic capacitors are usually in the form of broken or leak has been short, for leak detection or been short convergence we observe the following image.

Measure the test paper or ceramic capacitors.

• The image above is checked ceramic capacitor measurements, three capacitors C1, C2 and C3 have equal capacitance, the capacitor C1 is that good, the capacitor C2 and C3 detectors are capacitors has been short.
• When measuring capacitor C1 (from good) to a slightly larger needle then return to previous position. (Note the small focus too <1nF load, the needle will not release)
• When measuring capacitor C2 (capacitor detectors), we see the needle on the scale halfway and stopped does not return to previous position.
• When measuring the capacitor C3 (Capacitor been short) = 0 we see the needle on Ω and not return.
• Note: When measuring or checking the paper capacitors ceramic capacitors we have to clock in or x10KΩ x1KΩ scale, and to the island clockwise several times after that.

8.2) Measurement of test capacitors

Magnetized detectors or rarely been short as capacitor paper, but they dry out or damage in the form (dry chemicals inside the dielectric layer) to the capacitance of the capacitor is reduced, to check the convergence of, we often compare magnification of capacitor loaded with a good convergence with the same capacitance, the following picture illustrates the convergence of these tests.

Measurement of convergence test

• To check capacitor values ​​of 100μF C2 is the capacitance can be reduced or not, we use the new capacitor C1 also has the same capacitance and measurement comparisons.
• To watch in scale from x1Ω to x100Ω (the larger the capacitance to the lower scale)
• Measure and compare the two capacitor charging zoom, then the measuring stick we reversed several times.
• If two capacitor discharge capacitor load is equally good to check in on our reporter that loaded less capacitor C2 capacitor C2 so on have been dry.
• Where the needle back up without a capacitor detector.

Note: If the test capacitor directly on the circuit, we need to draw from an empty vessel in a vacuum capacitors, then tested as above.

9 - The types of problems and applications
9.1. Capacitors connected in series.

• The capacitor in series with the equivalent capacitance C TD is calculated by the formula: 1 / C td = (1 / C1) + (1 / C2) + (1 / C3)
• Where only two capacitors connected in series, the C td = C1.C2 / (C1 + C2)
• When connected in series, the withstand voltage of the capacitor voltage equal to the sum of the capacitor combined. TD U = U1 + U2 + U3
• When the capacitor connected in series, if it is the focus of attention should be paid dimensions of the capacitor, the negative first capacitor connected to the positive capacitor follows:

Capacitors connected in series capacitor in parallel

09.02 - Capacitors in parallel.

• The capacitor in parallel with the capacitance, the equivalent total capacitance of the capacitor combined. C = C1 + C2 + C3
• Withstand voltage of the capacitor voltage was roughly equal with the lowest voltage capacitor.
• If the capacitor of the capacitor must be connected in the same way Yin and Yang.

9.3 - Application of the capacitor.
Capacitors are used in many electrical and electronic engineering, in electronics, the capacitor is an indispensable component, each circuit has a certain utility as signal transmission, interference filters, power filters, oscillators, etc. .. ...
Here are some pictures illustrating the application of capacitors.
* Filter capacitors in the power circuit.

Capacitor filter circuit of the source.

• The source filter circuit as shown above, convergence of effective filter for DC voltage after the rectifier is to provide a flat load consumption, we see if there is no DC capacitor voltage after the diode voltage undulating, when the filter capacitor voltage is relatively flat, the larger the capacitor DC voltage is more flat.

* Capacitors in the oscillator circuit to two square pulse.

Multi-body oscillator circuit using two transistors

• You can mount on the circuit parameters given in the diagram.
• Two bright lights use LEDs in parallel with the polar CE mark of the second transistor,