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Step of 7 12.044P Refer to Figure 11.35 in the textbook. Calculate the value of Zener voltage at 125° Substitute 6.8 V for 125° C for 25° C for and 2 for =6.8+0.2 V Step of 7 The combination of the positive temperature coefficient of zener diode and the negative temperature coefficient of causes the voltage at the emitter of to rise. Calculate the emitter voltage of the transistor Substitute 7 V for 0.7 V for 125° C for T2 25° for and for TC =7.0-(0.7-0.2) =7.0-0.5 =6.5V Step of Calculate the base emitter voltage of the transistor Substitute 7 V for and for =0.5V Calculate the value of the resistance, R2 Substitute 0.5V for and 100 for 0.5 R2 Thus, the value of the resistance, R2 is Step of 7 Calculate the value of the resistance, Substitute 0.5V for 6.5V for and 100 for 6.5-0.5 = Thus, the value of the resistance, is 60 Step 7 Calculate the value of Zener voltage at 25° Substitute 6.8 V for 25° C for T2 25° for and 2 mV/°C for Calculate the emitter voltage of the transistor at 25° Substitute 6.8 V for 0.7 V for 25° C for 25° for T, and -2 mV/°C for =6.8-0.7 =6.1V Step of 7 Apply voltage division rule to calculate the base voltage of the transistor Substitute 60 for 5 for R2 and 6.1V for =6.1x0.0769 0.4692 V Step Calculate the value of collector current of transistor, Substitute 0.4692 V for 0.7 V for 25 mV for and 100 for 0.469-0.7 0.025 =0.01 Therefore, the collector current of transistor, at 25°C 0.01