Question

ECE 311 Test 1 Problem 3 3/9/11 Name In the given circuit, R2=100K, R?=1K, V2 = 25V, lima and the Zener diode has a breakdown voltage of 10 volts. The transistor has a ? of 100, Assume that a forward-biased diode has a .7V drop. R1 1k D4 a. Find V. b. Find VCE c. What is the operating mode of Q1? d. What is VCE if Vz=15V? e. If V1--1V, what is the operating mode of Q1? R2D3 D2 Q1V2 V1

Answer 1

JB = JB = 1 mA Jc = beta j B V B - 0.7 - 0.7 - 0.7 = 0 VB = 2.1 v JC = 100 times 1 = 10 mA JC = 10 mA venen diode is in Break down Therefore Diode Du is Revenue Biased as anode of D4 is at Lower potential compared to Cathode D2 D3 F, B Using KVL V_s - 100 times 0.1 - 0.7 - 0.7 - 0.7 = 0 Therefore vs = 12.1 V VCE = 25 - 10 1 times 10 times 10^- 3 times 10^3 - 0 VCE = 5 V A5 VCE > 0.2 V (sat) Transition is in Active region. if v2 = 15 V Then Diode D4 becomes \r\n Current through Diode = JD I = 25 - 1.4 - 15/1 = 8.6 mA VCE = 25 - 15 - 1 times 8.6 - 0 VCE = 1.4 v V1 = 1 V Using KVL 1 - 100 times I - 0.7 - 0.7 - 0.7 = Therefore i = - 11 mA There Q1 is in cut off
plz provide your feedback and rate it.