Basic Transistor

1 - Introduction to Transistor

1.1 - Structure of the Transistor. (Transistor)

Three layers of semiconductor transistors coupled together to form two connection 
PN junction, if the transplant in order to be PNP Transistor we agree, if 
the order pair NPN transistors have been back. in terms of structure 
Diode Transistor equivalent to two oppositely game.

Transistor Structure

• The three semiconductor layers are connected into three poles, the middle layer called 
  the original extreme denoted B (Base), B is very thin semiconductor layers and levels of 
  low impurities.
• The two outer semiconductor layers are connected to the emitter ( 
  Emitter) abbreviated as E, and drain or collector (Collector) 
  abbreviated as C, E and C semiconductor region having the same type of semiconductor (N or P type ) 
  but the size and concentration of various impurities should not permutations for 
  each other is.

1.2 - Principle of operation of the transistor.

* Considering the operation of the NPN transistor.

Circuit principles survey 
of NPN transistor

• We supply a DC source U CE in C and E poles in the (+) source in positive C and (-) source in positive E.
• DC Power U BE traverse limit switches and back on the poles B and E, in which the positive (+) to pin B, polar (-) to pin E.
• When the switch opens, we see that although the poles C and E 
  were still without power supply voltage, CE connection (at 
  this current I C = 0)
• When the switch is closed, connections are polarized PN agreement by which a current flows from (+) source U BE through switch => the R-limit lines => through each tank Pole (-) form the I B
• Once the I B occurs => immediately I have the C run through connection to CE light bulbs, and the I C I line up many times B
• So, obviously the I C is completely dependent on the I B and depends on a formula.

I C = β.I B

• Where I C is the line running through the CE connections
• I B is the line running through each tank
• β is the gain of the Transistor

Explanation : When a voltage U CE , but the electrons and holes can not pass the connection to form the PN junction current, the appearance of lines I BE
by P in polar semiconductor layer B is very thin and the concentration phase less complex, so the number of 
free electrons from the semiconductor layer N (positive E) adjacent to layer over 
a semiconductor P (pole B) a larger number of holes a lot, a small fraction 
of electrons that How to make the holes I B but most of the electrons attracted to the extreme C under the effect of voltage U CE => I made ​​the CE running through the transistor.

* Considering the operation of the PNP transistors.

The activity of PNP Transistor Transistor NPN quite similar, but the polarity of the power U CE and U BE back. Series I C from E to C is the I B from E to B.

2 - Symbols and shapes of the Transistor

2.1 - Transistor Symbols & shapes.

The symbol of the Transistor

Transistor Transistor the production of small-large

2.2 - Symbol (body Transistor)* 
currently on the market with a variety of countries Transistor products 
but the most common of the transistor of the Japanese, U.S. and Chinese 
national.

• Japanese Transistor : usually denoted as A ... B ... C ... D ... For example, A564, B733, C828, D1555
  Transistor symbols in which the A and B is convenient PNP Transistor is 
  denoted C and D are NPN Transistor reverse. the 
  transistors A and C are often small and of high working frequency 
  of the transistors B and D are often large and the frequency of working 
  less.
• Transistor by U.S. producers . usually denoted as 2N ... eg 2N3055, 2N4073 , etc. ...
• Transistor produced by China : 
  Start with number 3, followed by two letters. The letter said most of 
  the ball type: text A and B are balls agreement, C and D is the ball backwards, letter 
  Monday that features: X and P is the ball frequency, A and G are highly polished 
  band. The numbers in the following order of product only. Example: 3CP25, 
  3AP20 etc. ..

2.3 - How to determine the true E, B, C of the transistor.

• With the kind of small transistors , the order of C and B foot, depending on the shadow of the curse of any country, but E is always the left leg if you like the picture below to Transistor
• If the Japanese production Transistor: Transistor eg C828, A564 in the middle of the leg C, B on the right foot.
• If China is producing transistors are in the middle leg B, C on the right foot.
• However, some clones produced transistors are 
  not in this order => to know the exact method we use to measure 
  with a multimeter.

The small transistor.

• With the production of large transistors (see below), most have the same order of truth is left is ultra B, C, and in between is extremely positive right is E.

Transistor capacity of most often 
ordered as on foot.

* Measure the leg B and C determined

• Transistor With a capacity of conventional small legs E in 
  the left so we just define leg B and leg C is inferred leg 
  again.
• To watch x1Ω scale, fixed a measuring rod on each 
  leg, the other sticks move the legs rest, if the needle on the = same 
  is true with fixed rod B is true, if the rod is a rod fixed clock 
  black Transistor is the opposite, the red rod is a convenient Transistor ..

3 - Method of test Transistor
Transistor 
the operation can fail for many reasons, such as damaged by heat 
, humidity, due to high voltage or by the quality of self- 
Transistor, Transistor to check your structure of our mind.

Components of the Transistor

• NPN Transistor Test against the same test 
  match two common anode diode, is extremely common point B, if measured from B to C 
  and B to E (black sticks in B) is equal to two diode measured upon 
  direction => Metal up, all other cases needles measure up.
• Check PNP Transistor similar tests upon 
  two poles Katot Diode general play, the common point B of the transistor is positive, if 
  measured from B to C and B to E (red rods in B) is equivalent to measuring the two 
  -dimensional diode agreement = > kim up, all other metal case measuring 
  no more.
• Contrary to the above is broken Transistor.
• Transistor can be broken in the case . * Measured positively from B to E or from B to C => metal on the transistor is not cut off BE or BC * Measured from B to E or from B to C on both metal dimensional detector is short or BE or BC. * Measured between C and E has been short-needle on the CE.
  
  
  
  
  

* The images illustrate the measurement test Transistor.

Transistor measurements for good.

• Illustration of measurements : First look at the 
  symbols we know is the ball on the opposite transistor, and the 
  foot of the ECB Transistor, respectively (based on the name Transistor). <review the determination foot Transistor>
• Step 1: Preparing to watch at the scale measured x1Ω
• Step 2 and Step 3: Measure positively BE and BC => kim up.
• Step 4 and Step 5: Measure the reverse BE and BC => no more needles.
• Step 6: Measure between C and E needles up
• => Football good.

------------------------

Transistor measurements that has been short-BE

• Step 1: Prepare.
• Step 2: Measure the agreement between B and E needles up = 0 Ω
• Step 3: Measure the contrast between B and E needles up = 0 Ω
• => Football Short-BE

----------------------

Measurements for the ball broke BE

• Step 1: Prepare.
• Step 2 and 3: Measure both directions between B and E on the needles.
• => Football BE off

-------------------

Measurements showed that the ball has been short-CE

• Step 1: Prepare.
• Step 2 and 4: Measure both directions between C and E needles up = 0 Ω
• => Football Short-CE
• Where measured between C and E is a little metal detectors CE.

4 - The specifications of the Transistor

4.1 - The specification of the Transistor

• Maximum Current: The current limits of the transistor, to overcome the limitations of this transistor will be damaged.
• Voltage: The voltage of the transistor limits placed on poles CE, pass transistor limits the voltage will be disruptive.
• Cutoff frequency : The frequency limits of normal working Transistor, beyond this frequency is amplified by the transistors is reduced.
• The gain : The ratio of the changes I CE How many times larger than stream I BE
• Maximum Power : When operating a transistor dissipation of P = U CE . I CE if the production exceeds the maximum capacity of the transistor, the transistor will be damaged.

4.2 - Some special Transistor.

* No. Transistor (Digital Transistor) : Transistor Transistor number is made ​​up as often but leg B are fighting a few tens of KΩ resistor

No. Transistor commonly used 
in the switch circuit, logic circuit, control circuit, when active 
people can take action directly apply 5V to pin B command to control the 
light breaks open.

Illustrating the application of Transistor Digital

* Symbols: Transistor 
Digital signatures are often DTA ... (amaranth agreement), 
DTC ... (reverse lights), KRC ... (reverse lights) KRA ... (lights 
upon), RN12 ... (reverse lights), RN22 ... (lights agreement), UN ...., KSR ... 
. For example, DTA132, DTC 124, etc. ...

* Transistor capacity of the line (the level of)

Transistor the major export 
is often called shells. Number of lines, number of sources, etc. .. the shell is designed 
to control the high voltage transformer or power pulse operation, they 
usually have high operating voltage and for the big bear. 
The number of lines (Ti of color) often play more diode 
in parallel with buffer pole CE.

 

Number of production lines in the color TV

5 - Polarization for Transistor

5.1 - Power Supply for Transistor (Vcc - supply voltage)

To use the transistor in the circuit we need to grant 
it a power source, depending on the purpose for which power is granted 
directly to the transistor or through resistors, coils etc. ... source 
Vcc power for the conventional transistor is maximum power for CE.

Power Transistor Vcc for vice and consent

• We see that: If the NPN transistor is opposite the source Vcc is positive (+), if the agreement PNP Transistor Vcc is the source of the negative (-)

5.2 - The Natural (polarization) to Transistor.

* The natural means for 
a power source to pin B (the back bias) to put transistors on 
ready status, ready to amplify the signal 
even if very small.

* Why the bias to the transistors it is willing to work? : To understand this we consider the two diagrams above:

• In the two transistor circuits used to amplify the 
  signal, a circuit B is not the natural foot and leg B is a circuit 
  bias via RDT.
• The source signal into the amplifier often have records 
  of very small (from 0.05 V to 0.5 V) when put in leg B (light without 
  bias) the signal is not sufficient to produce a line I BE (special the connection you must have 0.6 V PN new line running through) => so I do not have the CE => drop on Rg = 0V and the output voltage Vcc pin C =
• In diagram 2, RDT Transistor with bias => I have the BE , when giving a small signal on pin B => make the line I BE up or down => the line I CE also 
  increased or reduced pressure drop in the Rg also change => and outputs 
  a signal obtained similar input but have greater amplitude.

=> Conclusion : The natural (or polarization) that is creating an electrical current I BE original, a drop in initial Rg as a source of extremely weak signals into B, the line I BE will increase or decrease => line I CE also increase or decrease => to drop the Rg also increase or decrease => and this drop is the signal we need to get out.

5.3 - mach Some other bias.

* Bias circuit uses two different power sources .

Bias circuit uses two different power sources

* Mach bias power is distributed pressure

To amplify the signal sources of different strength, the 
bias circuit is often used to add resistance distribution from B to match pressure RPA 
Mass.

Bias resistor circuit voltage RPA classification

* A bias feedback circuit.The 
bias circuit is resistance from the output (positive C) to input (pole B) 
This circuit works to improve stability for the operation amplifier circuit.