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Dsa 9

The document describes an experiment using a 555 timer IC to design astable and monostable multivibrators. For the astable multivibrator, the author calculates the resistor values needed to produce time periods of 150ms with 80% duty cycle and 100ms with 90% duty cycle. For the monostable multivibrator, the author calculates resistor values to produce pulse widths of 90ms, 180ms, and 280ms triggered by the output of the 150ms 80% duty cycle astable multivibrator. Waveforms and calculations are shown verifying the circuit designs meet the specified parameters.

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Merlin Joy
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40 views12 pages

Dsa 9

The document describes an experiment using a 555 timer IC to design astable and monostable multivibrators. For the astable multivibrator, the author calculates the resistor values needed to produce time periods of 150ms with 80% duty cycle and 100ms with 90% duty cycle. For the monostable multivibrator, the author calculates resistor values to produce pulse widths of 90ms, 180ms, and 280ms triggered by the output of the 150ms 80% duty cycle astable multivibrator. Waveforms and calculations are shown verifying the circuit designs meet the specified parameters.

Uploaded by

Merlin Joy
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Digital Systems and Applications Lab

Experiment 9
Merlin Joy
21 November 2021

1. Design an astable multivibrator of


(a) time period 150 millisecsonds and 80% Duty Cycle
(b) time period 100 millisecsonds and 90% Duty Cycle
using 555 Timer IC. Analyze the waveforms at the output terminal and across the capacitor and
compare the obtained values with the given ones.
2. Design a monostable multivibrator that stays in an unstable state for
(a) time of 90 millisecsonds
(b) time of 180 millisecsonds
(c) time of 280 millisecsonds
Use the output of the astable multivibrator designed in part a(ii) as the trigger input. Analyze the
waveform obtained across the capacitor and the output terminal. Analyze the results and discuss
them.

1 Astable Multivibrator
1.1 T = 150 millisecsonds, Duty Cycle = 80%

We need to find the resistance required to create this circuit.

Let capacitance C = 1µF


tc
Now, Duty cycle = × 100%
T
tc = 0.12s

T = tc + td

td = 0.03s

Now, td = 0.693 RB C
0.03 ∗ 10−6
RB = = 43290 Ω
0.693
RA + RB 80
Also, Duty cycle = =
RA + 2RB 100
RA = 3RB = 129870 Ω

1
Figure 1: Circuit Diagram

tc = 125.44 millisecs

2
td = 29.77 millisecs

T = 155.21 millisecs
125.44
Duty cycle = × 100% = 80.82%
155.21

3
1.2 T = 100 millisecsonds, Duty Cycle = 90%

We need to find the resistance required to create this circuit.

Let capacitance C = 1µF


tc
Now, Duty cycle = × 100%
T
tc = 0.09s

T = tc + td

td = 0.01s

Now, td = 0.693 RB C
0.01 ∗ 10−6
RB = = 14430 Ω
0.693
RA + RB 90
Also, Duty cycle = =
RA + 2RB 100
RA = 3RB = 115440 Ω

Figure 2: Circuit Diagram

4
tc = 91.42 millisecs

td = 10.63 millisecs

5
T = 102.06 millisecs
91.42
Duty cycle = × 100% = 89.57%
102.06

2 Monostable Multivibrator

2.1 ω = 90 millisecs

ω = 1.1 RA C

RA = 81818 Ω

Figure 3: Circuit Diagram

6
ω = 90.01 millisecs

Tinput = 102.76 millisecs

7
Toutput = 102.76 millisecs

Tinput > ω

Toutput = Tinput

2.2 ω = 180 millisecs

ω = 1.1 RA C

RA = 163636 Ω

Figure 4: Circuit Diagram

8
ω = 180.72 millisecs

Tinput = 102.76 millisecs

Tinput < ω < 2Tinput

9
Toutput = 206.24 millisecs

Toutput = 2Tinput

2.3 ω = 280 millisecs

ω = 1.1 RA C

RA = 254545 Ω

Figure 5: Circuit Diagram

10
ω = 282.07 millisecs

Tinput = 103.47 millisecs

2Tinput < ω < 3Tinput

11
Toutput = 309.71 millisecs

Toutput = 3Tinput

12

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