Transistor as voltage amplifier

How to use transistor as voltage amplifier

What you need.
1. 2N3904 transistor, (Any Small Signal Transistor )
2. Four resistors with following values
3. 10 uf capacitor 

The Class A voltage amplifier is shown bellow. The required values of resistor can be taken as follows.

Assume:

            I_E = 1mA (The first thing is to decide on what emitter current should be used. A current of around 1 mA is usually quite satisfactory for audio amplification unless there is some special reason for selecting otherwise)

            V_E = 2V ( The next decision is to select an emitter voltage (Ve). The higher this voltage, the greater is the emitter current stability in the presence of temperature variation and for variation in the value of Hfe.)

Then R_E can be obtain using ,

R_E  =  V _E / I _E   = 2V/ 1mA = 2k

R_L can be obtain as ,

R_L = (V_cc – V_e)/I_c but we know  I_c ~I_E    

R_L  =(V_cc – V_e)/I_c =  (9V – 2V)/ 1mA  =  7k 

The bleed current through the R1 and R2 must be 10 times as I_B 

 I_C  = H_FE.I_B 

R1 = (V_CC – Vb) / 10. I_{B  =} R₁ = (V_cc – V_E - V_BE)/10.I_b  = (9V – 2V - .7 V ) * 100 /10. =  63k

R₂= V_B / 9 I_b  = (V _E  + V_BE)  /9 I_b => R_{2= 3k}

 Reference: http://users.tpg.com.au/users/ldbutler/TransisVoltAmp.htm