Design and Verification of Fixed Bias Circuits

Aim:

To design a fixed bias circuit and observe stability by changing β of the given transistor in CE configuration.

Apparatus:

1. Transistors (BC 107) with different β values
2. R.P.S (0-30V) 2 No.s
3. Resistors (from design values)
4. Bread board and connecting wires

Circuit Diagram:

Fixed Bias Circuit:

Calculations:

Fixed Bias Circuit:

1. Given V_CC = 10V, I_C = 4mA, V_CE = 6V, V_BE = 0.6V, β = 100
2. I_C = I_B / β
3. R_B = (V_CC-V_BE)/I_B
4. R_C = (V_CC-V_CE)/I_C

Procedure:

1. Assemble the circuit on breadboard with design values    of RC, RB and β.
2. Apply VCC and measure VCE and VBE and record the readings in the table.
3. Without changing bias resistors, change the transistors with other β values and repeat the above step.
4. Repeat the above steps using the collector to base bias circuit and tabulate all the readings.

Observations:

Fixed Bias:

Precautions:

1. The supply voltage should not exceed the rating of the transistor.
2. Meters should be connected properly according to their polarities

Result:

Viva Questions:

1. What are the applications of fixed bias configuration?
2. What are the applications of collector to base bias configuration?
3. What are the disadvantages of fixed bias configuration?
4. How to overcome the disadvantages of fixed bias configuration.