Comprehensive Problems

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Comprehensive Problems

4.93 The circuit in Fig. 4.149 models a common-emitter transistor amplifier. Find ix using source transformation.

Figure 4.149

For Prob. 4.93.

4.94 An attenuator is an interface circuit that reduces the voltage level without changing the output resistance.

(a) By specifying Rs and Rp of the interface circuit in Fig. 4.150, design an attenuator that will meet the following requirements:

$$\frac{V_o}{V_g} = 0.125, \qquad R_{\text{eq}} = R_{\text{Th}} = R_g = 100 \ \Omega$$

(b) Using the interface designed in part (a), calculate the current through a load of RL = 50 Ω when Vg = 12 V.

For Prob. 4.94.

4.95 A dc voltmeter with a sensitivity of 10 kΩ∕V is used to find the Thevenin equivalent of a linear network. Readings on two scales are as follows: *

(a) 0–10 V scale: 8 V (b) 0–50 V scale: 10 V

Obtain the Thevenin voltage and the Thevenin resistance of the network.

4.96 A resistance array is connected to a load resistor R and a 9-V battery as shown in Fig. 4.151.

• (a) Find the value of R such that Vo = 1.8 V.
• (b) Calculate the value of R that will draw the maximum current. What is the maximum current?

Figure 4.151 For Prob. 4.96.

4.97 A common-emitter amplifier circuit is shown in Fig. 4.152. Obtain the Thevenin equivalent to the left of points B and E.

Figure 4.152

For Prob. 4.97.

4.98 For Practice Prob. 4.18, determine the current through the 40-Ω resistor and the power dissipated by the resistor. *

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