1 - amplifier
1.1 - The concept of contemporary khuyeh circuit.
Amplifier circuits are used in most electronic devices, such as audio-frequency amplifier circuit in Cassete, amplifiers, signal amplification in television color video etc ...
There are three main types amplifying circuit is:
1.2 - The operating mode of the amplifier.
The mode of operation of the amplifier is dependent on the polarization mode for Transistor, depending on the purpose of use that amplifier circuits are polarized to KD in mode A, mode B, AB mode or modes C
a) Circuit-mode amplifier A.
As the amplifier circuit to take the signal completely around with the input signal.
* Amplifying circuit mode A is used in the intermediate circuit as high-frequency amplifiers, intermediate frequency amplifiers, preamps etc. ..
Mode B amplifier circuits amplify only one half of the signal cycle, if amplifying the positive sale NPN transistor we use, if any sound amplifying selling we use PNP transistor, amplifier mode B without bias.
2 - The question of Transistor type
2.1 - General E Transistor-style questions.
E circuit-style common questions have played directly into the E pole mass or mass game capacitors down to drain components
AC signal pole put on poles B and C removed, the circuit diagram as follows:
3 - The cascade style
3.1 - Assembling stories through the capacitor.
* Diagram cascade circuit through the capacitor
4 - Method for testing single-stage amplifier
4.1 - In the amplifier circuit (mode A) how the polarization is correct.
1.1 - The concept of contemporary khuyeh circuit.
Amplifier circuits are used in most electronic devices, such as audio-frequency amplifier circuit in Cassete, amplifiers, signal amplification in television color video etc ...
There are three main types amplifying circuit is:
- Voltage amplifier: As if we put a circuit with small amplitude signals at the output we get a signal with greater amplitude repeatedly.
- Amplifying the electrical current circuit:
When we put a circuit with low intensity signal on the output we get a signal for strong amperage over several times. - Amplifying circuit capacity: As a circuit when we put out weak signals of input, output signal obtained with a capacity of more powerful, in fact amplifying circuit capacity is a combination of both amplifier voltage and current amplifiers do.
1.2 - The operating mode of the amplifier.
The mode of operation of the amplifier is dependent on the polarization mode for Transistor, depending on the purpose of use that amplifier circuits are polarized to KD in mode A, mode B, AB mode or modes C
a) Circuit-mode amplifier A.
As the amplifier circuit to take the signal completely around with the input signal.
A mode amplifier circuits amplify sell both the input signal cycle
* To Transistor operation mode A, we must bias voltage such that ~ 60% U CE ÷ 70% Vcc.
* Amplifying circuit mode A is used in the intermediate circuit as high-frequency amplifiers, intermediate frequency amplifiers, preamps etc. ..
b) Mach-mode amplifier B.
Mode B amplifier circuits amplify only one half of the signal cycle, if amplifying the positive sale NPN transistor we use, if any sound amplifying selling we use PNP transistor, amplifier mode B without bias.
Mode amplifier B only amplify a sell cycle of the input signal.
* Mode B amplifier circuit is often used in the production circuit of
push-pull amplifier as the audio output, the production of television
screens, in the push-pull output circuit, people use two lamps NPN and
PNP questions serial, each lamp will
amplify a sell signal cycle, two lights in the push-pull amplifier circuit to have the same specifications:
amplify a sell signal cycle, two lights in the push-pull amplifier circuit to have the same specifications:
* Circuit output amplifiers combine both A and B mode.
Circuit amplifiers have amply made: Q1 amplification mode A, Q2 and Q3 B-mode amplifiers, amplifier Q2
to sell a positive cycle, Q3 amplify sound for selling cycle.
to sell a positive cycle, Q3 amplify sound for selling cycle.
c) Circuit AB amplifier mode.
Mode amplifier AB amplifier circuit is similar in mode B, but with the good so that the voltage U BE tails Wholesale 0.6 V, the circuit is only amplifying the signal half cycle and overcome the distortion intersection of B mode amplifier circuit, this circuit is also used in the push-pull output circuit.
Mode amplifier AB amplifier circuit is similar in mode B, but with the good so that the voltage U BE tails Wholesale 0.6 V, the circuit is only amplifying the signal half cycle and overcome the distortion intersection of B mode amplifier circuit, this circuit is also used in the push-pull output circuit.
d) amplifying circuit in C mode
Amplifying circuit voltage U BE assigned reverse zone for the purpose of taking only the output signal is a top portion of the input signal, this circuit is often used in the signal separation circuit: pulse separation circuit example copper in color television sets.
Amplifying circuit voltage U BE assigned reverse zone for the purpose of taking only the output signal is a top portion of the input signal, this circuit is often used in the signal separation circuit: pulse separation circuit example copper in color television sets.
Amplifier applications in C mode sync pulse separation circuit color television.
2 - The question of Transistor type
2.1 - General E Transistor-style questions.
E circuit-style common questions have played directly into the E pole mass or mass game capacitors down to drain components
AC signal pole put on poles B and C removed, the circuit diagram as follows:
Voltage amplification circuit type E suffering from common, positive signal given in and taken out on pole B C
Rg: was found ghanh resistor, RDT: A bias resistor, RPA: A potentiometer resistor.
Characteristics of common E amplifier circuits.
- General E amplifier is often bias voltage U CE star for about 60% ÷ 70% Vcc.
- The signal amplitude greater than the amplitude obtained signal into multiple times, so the voltage amplifier circuit.
- Output current is greater than the input stream, but not significantly.
- Reverse-phase output signal with the input signal: because when the input voltage increases => the line I BE increases => the line I CE
increase => increased pressure drop across Rg => foot resulting voltage C decrease, and vice versa when the input voltage, the voltage reduction C leg rose => so the reverse-phase output voltage with the input signal . - E circuit-style common questions such as these are most commonly used in electronic devices.
2.2 - style C Transistor common problems.
C circuit-style public suffering leg match in mass or positive C source (Note: on the positive aspects of ac
source equivalent to mass), signal B are brought into and taken out on pole pole E, the circuit diagram as follows:
source equivalent to mass), signal B are brought into and taken out on pole pole E, the circuit diagram as follows:
Develop common type C circuit, the signal put in and took out on pole pole B E
Characteristics of common C amplifier.
- Incoming signal pole on pole B and E removed
- The signal amplitude of the input signal amplitude: Because each child is always worth approximately 0,6V so when voltage increases how much vacuum pressure B C also increased this much leg => so the signal amplitude the amplitude of the input signal.
- Output signal in phase with the input signal: As the voltage on the rise =>, the output voltage is increased, the voltage to decrease the output voltage decreases.
- The intensity of the stronger signal of the input signal intensity many times: Because the signal amplitude at increasing => line I BE will raise => line I CE also increased β times as first line I BE CE = BE β.I assuming the gain transistor has β = 50 times, increasing the line I BE 1mA => 50mA line I CE will increase, the line is the line I CE of the output signal, so the output signal there amperage more powerful than the input signal.
- On the application circuit in the amplifier many nights (Damper), before dividing the signal as many branches, people often used to amplify circuit Damper for better signal. In addition the application circuit is also very much in the voltage regulator circuit source (we'll find out in the next section)
2.3 - General B Transistor-style questions.
- Develop common circuit-style B signals brought into and taken out on foot E C leg, foot mass B is discharged through convergence.
- Type B Mach common questions are rarely used in practice.
General type B amplifier, voltage amplifier and not amplify the currents.
3 - The cascade style
3.1 - Assembling stories through the capacitor.
* Diagram cascade circuit through the capacitor
Beginning from the amplifying circuit - has two floors with each amplifier is coupled via capacitors.
- The above is the first amplifier circuit diagram from the cassette radio, amplifier circuit consists of two floors styled E suffering from common, the floors are multiplexed signal through the capacitor, the capacitor was used C1, C3, C5 connecting layer capacitors for AC signals to pass through and prevent the DC voltage, the capacitors C2 and C4 components work alternating exit from E down leg
mass, C6 is the source filter capacitor. - The advantage of the circuit is simple, easy to fit so very many circuits used in electronic devices, the disadvantage is not fully exploiting capabilities of transistor amplifier so the gain is not big.
- Above is the audio amplifier circuit, so the convergence of connection layer capacitors used have 1μF values from 10μF ÷.
- In the high-frequency amplifier circuit, the capacitor value connected with stories of a few nano-Fara.
3.2 - Assembling stories through the transformer.
* Intermediate frequency circuit diagram language used in Radio cascade transformer
* Intermediate frequency circuit diagram language used in Radio cascade transformer
Middle Floor of Radio Frequency language used cascade transformers.
- Above the intermediate frequency circuit diagram using the transformers Radio cascade, the output signal of this stage is coupled through the transformer to go into the rear floor.
- Advantages of the combination circuit impedance between layers thus optimally exploit the gain, more transformer primary winding can play parallel resonant capacitor to the circuit at a frequency amplifier Fixed.
- Cons: if the circuit operates in a wide frequency range, the frequency distortion, circuit complexity and fabrication space occupation.
3.3 - Pairing direct floor.
* Direct cascade type normally used in the manufacture circuit audio amplifiers.
Output circuit audio amplifiers have reverse-phase light Q1 coupled directly with the two light output Q2 and Q3.
4 - Method for testing single-stage amplifier
4.1 - In the amplifier circuit (mode A) how the polarization is correct.
Amplifier circuits are polarized correctly.
- Amplifier (mode A) is properly polarized circuit
U BE ~ 0,6V; U CE ~ 60% ÷ 70% Vcc - When the circuit is polarized right we can see, the signal amplitude of the largest and signal distortion.
4.2 - amplifying circuit (mode A) is polarized wrong.
Amplifier circuit is polarized wrong, too low voltage U CE.
Amplifier circuit is polarized wrong, high voltage U CE.
- When the circuit is polarized wrong (ie U CE is too low or too high), it was found that the distortion signal, the gain of the circuit is greatly reduced.
- Phenomenon will cause distortion on sound phenomenon being shy or obstruction in the audio-frequency amplifier circuit.
Method for testing an amplifying layer.
- An amplifying stories if we checked that U CE is too low or too high compared to the tails wholesale sources => amplify the stories that matter.
- If U CE is too low, it may be due to short CE (broken Transistor), or off Rg.
- If U CE is too high ~ Vcc may be broken or damaged Transistor RDT.
- A better amplify stories usually have:
U BE ~ 0,6V; U CE ~ 60% ÷ 70% Vcc
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