Electrical Engineering Answers

Design a TDM system to handle 3 PAM channels if the maximum input frequency of each channel is 5 kHz.

A stereo system with a resistance of 40 ohms was measured to have a current of 6.7 amperes. What is the voltage that is supplying the system?
A toaster has a resistance of 60 ohms and it’s plugged into a wall socket that supplies 120 volts. What is the current of the toaster?
Three 1.5 volt cells are powering a circuit that has a resistance of 6 ohms. What is the current running through the circuit?
To power a string of fifty Christmas lights with a resistance of 3 ohms each and with at least 1.2 amperes of current, what must be the minimum voltage of the power source?

(double checking answers)

In case if the load torque changes it is important to maintain the speed constant in
some applications. propose a suitable design to maintain the speed constant. Your
design should have the following components:

a) General block diagram for the overall system design.
b) Role of each block
c) Control system
[15 marks]
(v) Propose a suitable traction system block diagram with a simple methodology, in case
in the above EuRAIL case study if you want to replace the DC motor with a 3 phase
Induction motor. Also give 5 valid comments why to replace the DC motor with a 3
phase induction motor.
[10 marks]
(vi) Maglev trains are very common in developed countries for high speed operations. You
are given a 3 phase induction motor, can you modify the design to achieve Maglev
operation? If your answer is YES explain your design concept with appropriate
diagrams.

A combinational circuit has four inputs (A, B, C, D) and three outputs (X, Y, Z). XYZrepresents a binary number whose value equals the number of 1’s at the input. For example if ABCD  1011,XYZ  011. (a) Find the minterm expansions for X,Y,and Z. (b) Find the maxterm expansions for Y and Z.

Design a TDM system to handle 3 PAM channels if the maximum input frequency of
each channel is 5 kHz.

Given a forward biased si diode with I = 1mA. If the diffusion capacitance is Cd =1microferad , what is the diffusion Length Lp? Assume that the doping of the P-side is much greater than that of the n-side . Use Dp = 13metersquare second.

Compare CE, CB, CC Configuration.

a- Design an emitter follower having Ri = 500k and R0 = 20 ohm. Assume hfc = 50, hie = 1k, hce = 25 micro ampereN.
b- find AI and AV for the emitter follower of part a

Show that the voltage gain of an emitter follower circuit is close to unity.

Discuss Eber's Holl model for a transistor.