High Institute for Engineering & Technology, AL-Obour Electrical Eng. Dept, 4

th Year, Electronics & Comm. Section

Course Title : Electronics for Instrumentations ELC (426) Sheet 1

Dr. Eng. Ibrahim F.Tarrad :Instructor

Eng. Saad EL Sayed

Problem 1.1: The maximum output voltages of each of the voltage comparators shown in Figure 1 are 15 V. Sketch the output waveforms for each when vin is a 10- V- PK sine wave. (In each case, show vin and vo on your sketch, and label voltage

levels where switching occurs.)

vin

vo

(a)

vo

(b)

-8 V

vin

vo

-6 V

vin

(c)

+4 V

vin

vo

(d)

-

-

-

-

++

++

Figure 1

Problem 1.2: Repeat problem 1.1 when each of the v+ and v- inputs are interchanged. Problem 1.3: The output of comparator shown in Figure 2 switches between +10 V

and -10 V.

a. Find the lower and upper trigger levels. b. Find the hysteresis. c. Sketch the hysteresis loop.

d. Sketch the output when vi is a 10 V- pk sine wave.

Figure 2

Problem 1.4: Repeat problem 1.3 when VRef = +4V, under the assumption that the comparator output switches between +10 V and -5 V.

Problem 1.5: Assume VCC = 12 V and VSat = 0.9 VCC. If a sine wave of 10 V is applied to the circuit shown in Figure 3. Calculate threshold

levels and plot input and output waveforms.

Figure 3

-4 V

vin

vo

-

+

1K?3K?

vin -

+