TIMER IC APPLICATIONS -II( MONOSTABLE MULTIVIBRATOR) - Computer Programming

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## Monday, April 4, 2011

TIMER IC APPLICATIONS -II
( MONOSTABLE MULTIVIBRATOR)

To design a monostable multivibrator with tp = 0.616 ms , assume C = 0.01 µF

AIM:

To design a monostable multivibrator for the given specifications using 555 Timer IC.

APPARATUS REQUIRED:

 S.No Name of the Apparatus Range Quantity 1. Function Generator 3 MHz, Analog 1 2. CRO 30 MHz 1 3. Dual RPS 0 – 30 V 1 4. Timer IC IC 555 1 5. Bread Board 1 6. Resistors 7. Capacitors 8. Connecting wires and probes As required

THEORY:

A monostable multivibrator often called a one-shot multivibrator is a pulse generating circuit in which the duration of the pulse is determined by the RC network connected externally to the 555 timer.  In a stable or stand-by state the output of the circuit is approximately zero or at logic low level.  When an external trigger pulse is applied, the output is forced to go high (approx. Vcc).  The time during which the output remains high is given by,

tp = 1.1 R1 C

At the end of the timing interval, the output automatically reverts back to its logic low state.  The output stays low until a trigger pulse is applied again. Then the cycle repeats.
Thus the monostable state has only one stable state hence the name monostable.

PIN DIAGRAM:

CIRCUIT DIAGRAM OF MONOSTABLE MULTIVIBRATOR:

DESIGN:

Given  tp = 0.616 ms = 1.1 R1 C
Therefore, R1 = _____________

PROCEDURE:

1. Connections are given as per the circuit diagram.
2.  + 5V supply is given to the + Vcc terminal of the timer IC.
3. A negative trigger pulse of 5V, 2 KHz is applied to pin 2 of the 555 IC
4. At pin 3 the output waveform is observed with the help of a CRO
5. At pin 6 the capacitor voltage is obtained in the CRO and the V0 and Vc voltage waveforms are plotted in a graph sheet.

OBSERVATIONS:

 S.No Amplitude( No. of div xVolts per div ) Time period( No. of div x Time per div ) ton toff 1. Trigger input 2. Output Voltage , Vo 3. Capacitor voltage , Vc

MODEL GRAPH:

RESULT:

The design of the Monostable multivibrator circuit was done and the input and output waveforms were obtained.