22-03-2014, 10:15 AM
Multivibrators
Aim:
To construct a (a) astable and (b) monostable multivibrator using IC 555.
Procedure:
(a) Assemble the astable circuit shown in Fig. 7.1. Trace the output waveform.
Try to use the control voltage terminal and vary the output pulse width and observe the
output waveform. Calculate the frequency of the output waveform and the duty cycle.The
square wave output will have frequency f= 1.4/[C (R +2R )] . Repeat for different R , R and
C values.
Compile the results and enclose the traced waveform.
Try-out: Redesign the circuit for operation at approximately 1 kHz with an approximate duty
cycle of 50%. Show the calculations for R_A, R_B and C.
(b) Construct the circuit as shown in Fig 7.2. Connect the circuit output to the CRO. Trace the
output wave form. Calculate the width of the output pulse. What should be the value of R
for the in the same monostable circuit that generates pulses with width half the value.