problem 1:

a) Draw and describe the functional block diagram of IC 555.
b) describe the functioning of 555 in Monostable configuration.
 
problem 2:

a) describe how astable mode of 555 can be modified to get a square wave generator.

b) Design a 555 based square wave generator to produce a symmetrical square wave of 1 KHz. If V_CC = 12V. Draw the voltage across timing capacitor and the output.
 
problem 3:

a) Describe the 555 timer

i) Monostable multivibrator application in Pulse Width Modulation.
ii) Astable multivibrator application in FSK generator.

b) A 555 timer is configured to run in astable mode with R₁ = 20K and R₂ = 8K and C = 0.1uf. Determine the output frequency and duty cycle.
 
problem 4:

a) Design an astable multivibrator using 555 timer to produce a square wave of 2 KHz frequency and 70% duty cycle. Draw the circuit with all component values.

b) describe how a PLL is used as a frequency multiplier.
 
problem 5:

a) describe the role of the basic building blocks of PLL.

b) Determine the DC control voltage v_c at lock if signal frequency f_s = 10 KHz, VCO free running frequency is 10.66 KHz and the voltage to frequency transfer coefficient of VCO is 6600 Hz/V.
 
problem 6:

a) Draw the schematic circuit diagram of the following and describe their working.

i) Analog phase detector.

ii) VCO.

Derive necessary expressions.

b) What is their role in PLL? describe.
 
problem 7:

a) Describe how frequency division and multiplication can be achieved using a Phase Locked Loop.

b) Draw the circuit of a PLL AM detector and describe its operation.