The core component of enlarge circuit is dynatron, want to want to have certain knowledge to dynatron so. The sort of the enlarge circuit that makes with dynatron is more, we come with a few commonly used kinds explanation (the 1) that be like a graph. Graph 1 it is the basic enlarge circuit that altogether shoots, general some of what content do we master to magnifying the road wants?

 

(1) analyses the action; of each component in circuit

 

(2) liberates the enlarge principle; of big circuit

 

(3) can analyse the static job of computational circuit to nod;

 

(4) understands the setting end that static job orders and method.

 

Above 4 in, last outbalance.

 

Graph 1 in, c1, c2 is coupling capacitance, coupling removes signal namely transfer function, capacitor can the class after signal signal class coupling arrived once upon a time, because,be capacitance the voltage of two end cannot choppy, after inputting end to input communication signal, the voltage because of two end cannot mutation because, the voltage that outputs end can follow the communication signal that inputs upright input changes together, carry signal coupling to output from the input thereby. But those who a bit want to explain is, capacitance the voltage of two end cannot choppy, but not be to cannot change.

 

R1, R2 slants for the dc of dynatron V1 buy resistor, what calls dc to slant buy? Simple for, charge for the making of sth. should have a meal. Requirement dynatron works, want to offer certain working condition first surely, electronic component is to ask to have what electric energy supplies certainly, do not make circuit otherwise.

 

In the working requirement of circuit, the first condition is to ask to want to stabilize, so, power source must be direct current source, call dc to slant so buy. Why be to pass resistor to come power supply? Resistor seems the faucet in water supply, with adjust of voltaic size. So, the “: of status of 3 kinds of jobs of dynatron? ?rdquo; of glutinous of lowing ⒎ of ズ of ⒈ of Piao a low bank of earth between fields slants by dc buy decision, in the graph 1 in, was decided namely by R1, R2.

 

Above all, we should know how the status of 3 kinds of jobs of differentiate dynatron, simple for, differentiate job works at why be being planted condition can come according to the size of Uce differentiate, uce is adjacent at VCC of power source voltage, criterion dynatron stops at carrying with respect to the job condition, carry stop dynatron of condition that is to say basically does not work, ic electric current is lesser (it is 0) about, so because R2 has flowed without electric current, voltage is close to 0V, uce is so adjacent at VCC of power source voltage.

 

If Uce is received,be bordering on 0V, criterion dynatron works at saturated condition, what is meant by saturated condition? That is to say, ic electric current reached maximum, calculate Ib to increase, it also cannot increase again.

 

Above we call two kinds of position commonly switch condition, outside dividing these two kinds, the 3rd kind of condition is enlarge condition, measure Uce to receive the in part that is bordering on power source voltage commonly. If measure Uce deflection VCC, criterion dynatron incline to stops at carrying condition, if measure Uce deflection 0V, criterion dynatron incline to at saturated condition.

 

 

Enlarge circuit, it is the output after the input signal magnifies, (Have voltage enlarge commonly, voltaic enlarge and power magnify a few kinds, this does not discuss in this inside) . Say we want the signal of enlarge first, with sine communication signal is exemple say. In analysing a process, can changing considering signal size only is to have having negative, other does not say. Mention above in the graph in circuit of 1 enlarge circuit, the setting that static job nods approachs the in part at power source voltage for Uce, why?

 

This is to make signal is enjoying the metabolic space that can have semmetry, when be inputted without signal, namely signal input is 0, hypothesis Uce is the half of power source voltage, we are when it one horizontal, as a reference point. When input signal increases, criterion Ib increases, ic electric current increases, criterion the voltage U2=Ic×R2 of resistor R2 can increase subsequently, uce=VCC-U2, meeting decrescent. U2 can be achieved on Dali talking most be equal to VCC, criterion Uce is the smallest can achieve 0V, this is to say, when input letter increases, uce is the biggest change is the VCC change from 1/2 to 0V.

 

Manage together, when the input signal decreases Xiaoshi, criterion Ib is reduced, ic electric current is reduced, criterion the voltage U2=Ic×R2 of resistor R2 can be reduced subsequently, uce=VCC-U2, can greaten. In the input the letter decreases Xiaoshi, uce is the biggest change is the VCC change from 1/2 to VCC. Such, when input signal happens to bearing change inside certain limits, uce is what there is a semmetry if allowing to losing span with 1/2VCC, pursue commonly so the setting that job of 1 static state nods approachs the in part at power source voltage for Uce.

 

Should design Uce into receive the in part that is bordering on power source voltage, this is our purpose, but how can you just design Uce into receive the in part that is bordering on power source voltage? This is method.

 

Here should know a few things first, the first is the Ic that we often say, Ib, they are the collector electric current of dynatron and base electric current, they have a concern is Ic=β×Ib, but our begin to learn when, the teacher is apparent did not tell us, is Ic, Ib how old is talent suitable? This problem answers harder, because the thing of drag in is relative much, but generally speaking, to small-power canal, set Ic to arrive in zero milliampere commonly a few milliampere, power canal is in in a few milliampere arrive a few milliampere, high-power canal arrives in a few milliampere a few how.

 

In the graph 1 in, set Ic to be 2mA, criterion the block value of resistor R2 can be calculated by R=U/I, VCC is 12V, criterion 1/2VCC is 6V, the block value of R2 is 6V/2mA, for 3KΩ . Ic set is 2 milliampere, criterion Ib can be rolled out by Ib=Ic/β , the extraction that crux is β was worth, β takes a cost theoretically commonly 100, criterion Ib=2mA/100=20#A, criterion R1=(VCC-0.7V)/Ib=11.3V/20#A=56.5KΩ , but actually, the β value that small-power provides is far more than 100, be in 150 to 400 between, taller perhaps, so if press above consideration will do, circuit is in saturated condition likely, so sometimes we are not clear, computation is right, but cannot use actually, because coach actually a bit lesser,this is, point out theory and real difference. The effect that this kind of circuit suffers β to be worth is big, everybody when calculation is same, but the result that does is not certain and same. That is to say, the stability of this kind of circuit is poor, actual application is less. But if instead pursues,the cent of 2 presses type to slant buy circuit, the analytic computation of circuit and actual circuit are measured relatively adjacent.

 

In the graph the cent of 2 presses type to slant in buy circuit, same our hypothesis Ic is 2mA, uce design is 6V into 1/2VCC. Criterion how should R1, R2, R3, R4 take a cost. Is computational formula as follows: ? Design of leech Ce is 6V into 1/2VCC, criterion Ic×(R3+R4)=6V;Ic≈Ie. Can cipher out R3+R4=3KΩ , such, how much is R3, R4 each?

 

General R4 takes 100Ω , r3 is 2.9KΩ , actually we take R3 continuously commonly 2.7KΩ , because there is 2.9KΩ in E24 set resistance, take the distinction with value 2.7KΩ and 2.9KΩ great never mind. Because of R2 the voltage of two end is equal to Ube+UR4, namely 0.7V+100Ω×2mA=0.9V, we set Ic to be 2mA, β takes a cost theoretically commonly 100, criterion Ib=2mA/100=20#A, there is an electric current to want here estimated, the electric current that has shed R1 namely, take a value to be Ib commonly 10 times the left and right sides, take IR1200#A. Criterion R1=11.1V/200#A≈56KΩR2=0.9V(/200-20)#A=5KΩ; considers actually β value may be ambitious at 100, take a value actually of R2 to be 4.7KΩ so. Such, the extraction of R1, R2, R3, R4 is worth it is 56KΩ respectively, 4.7KΩ , 2.7KΩ , 100Ω , uce is 6.4V.

 

In above analytic computation, put forward hypothesis for many times of what, this is necessary in actual application, a lot of moment need a referenced value to calculate, but often do not have however, the face is we are not familiar with all sorts of parts of an apparatus here, 2 was to forget a thing, ourselves just is the person that uses circuit, a few data are OK him set, can take roundabout way less so.