05-02-2013, 03:57 PM
ASTABLE MULTIVIBRATOR
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AIM:
To design an astable multivibrator circuit for the given specifications using 555 Timer IC.
THEORY:
An astable multivibrator, often called a free-running multivibrator, is a rectangular-wave-generating circuit. This circuit do not require an external trigger to change the state of the output. The time during which the output is either high or low is determined by two resistors and a capacitor, which are connected externally to the 555 timer. The time during which the capacitor charges from 1/3 Vcc to 2/3 Vcc is equal to the time the output is high and is given by,
Similarly the time during which the capacitor discharges from 2/3 Vcc to 1/3 Vcc is equal to the time the output is low and is given .
PROCEDURE:
1. Connections are given as per the circuit diagram.
2. + 5V supply is given to the + Vcc terminal of the timer IC.
3. At pin 3 the output waveform is observed with the help of a CRO
4. At pin 6 the capacitor voltage is obtained in the CRO and the V0 and Vc voltage waveforms are plotted in a graph sheet.
RESULT:
The design of the Astable multivibrator circuit was done and the output voltage and capacitor voltage waveforms were obtained.