Complete Electronics Self-Teaching Guide with Projects

Self-Test

These questions test your understanding of the concepts introduced in this chapter. Use a separate sheet of paper for your diagrams or calculations. Compare your answers with the answers provided.

For the first three questions, use the circuit shown in Figure 4.30. The objective is to find the value of R_B that turns the transistor ON. As you may know, resistors are manufactured with “standard values.” After you have calculated an exact value, choose the nearest standard resistor value from Appendix D, “Standard Resistor Values.”

Figure 4.30

1. R_C = 1 kΩ, β = 100

R_B = _____

2. R_C = 4.7 kΩ, β = 50 R_B = _____

3. R_C = 22 kΩ, β = 75

R_B = _____

For questions 4–6, use the circuit shown in Figure 4.31. Find the values of R₃, R₂, and R₁ that ensure that Q₂ is ON or OFF when the switch is in the corresponding position. Calculate the resistors in the order given. After you find the exact values, again choose the nearest standard resistor values.

Figure 4.31

Note Rounding off throughout a problem, or rounding off the final answer, could produce slightly different results.

4. R₄ = 100 ohms, β₁ = 100, β₂ = 20.

R₃ = _____

R₁ = _____

R₂ = _____

5. R₄ = 10 ohms, β₁ = 50, β₂ = 20.

R₃ = _____

R₁ = _____

R₂ = _____

6. R₄ = 250 ohms, β₁ = 75, β₂ = 75.

R₃ = _____

R₁ = ...