NET-Electronics qs-Descriptive and problem type

1 What are diode approximations?
A current of 2mA passes through a silicon diode of bulk resistance 25Ω. Find the voltage across the diode
2 Explain a Zener diode voltage regulator.
A 9V regulator power supply is required to run a car stereo system with a 12V battery. A zener diode with Vz= 9V and Pmax =0.25V is used as voltage regulator. Find the value of the series resistor
3 Currents I1 and I2 flow when large voltages V1 and V2 are applied to a semi-conductor diode. If V1 =2 V2 show that the value of the reverse saturation current is I0 = I22 /I1 .
4 Explain transistor as switch. With a diagram explain the voltage divider method of biasing and find the Q-point
5 A silicon transistor with β=55 is used in a voltage divider circuit. If Vcc=22.5V and VBE=0.6V, Rc =5.6K, RE=1K R1=90K, R2=10K find the Q=point and the stability factor.
6 Explain the UJT operation. What is intrinsic stand-off ratio? A UJT has a inter base resistance of 10K. It has RB =6K with IE=0. Find the UJT current if VBB=20V and VE is less that VP. Also find η, VA2 and VP2
7 The saturation drain current of JFET is 8.6mA when the gate voltage is zero. If the pinch-off voltage is -3V, calculate the drain current when the gate voltage is -1V.
8 With a suitable diagram explain the working of Hartley oscillator. Derive an expression for its frequency.
9 A certain radio receiver delivers and output of 3.6W. Find the power output required to produce a power gain of 10dB.
10 An inverting amplifier has Rf=2M and R1=2k. Find its scale factor.
11 What are combination logic gates. \give their logical equations and truth tables
12 How will you implement OR, AND, NOT, NAND using NORs.
13 How will you convert binary code into Gray code? Illustrate with example
14 Design a logic circuit to implement the operation specified in the truth table below
I------n--p-u --t o/p
A B C Y
0 0 0 0
0 0 1 0
0 1 0 0
0 1 1 1
1 0 0 0
1 0 1 1
1 1 0 1
1 1 1 0