Design and implementation of an astable multivibrator

Monday Esiri Amagre 1, Paul Erungworo Okayim 2, * and Anthony Chukwudi Aloamaka 3

1 Department of Mechanical Engineering, Faculty of Egineering, Delta State University, Nigeria.
2 Department of Physics, Faculty of Physical Science, University of Calabar, Nigeria.
3 Department of Electrical/Electronic Engineering, Faculty of Engineering, Delta State University, Nigeria.
Research Article
World Journal of Advanced Research and Reviews, 2024, 22(03), 2014–2019
Article DOI10.30574/wjarr.2024.22.3.1041
Publication history: 
Received on 22 May 2024; revised on 28 June 2024; accepted on 30 June 2024
The purpose of this paper was to design and implement an astable multivibrator circuit using a 555 timer integrated circuit (IC). An astable multivibrator is a type of electronic oscillator that generates a continuous stream of rectangular voltage pulses without any external triggering. The key motivation behind this work was to develop a simple and cost-effective astable multivibrator that can generate waveform signals for various timing and pulse generation applications. The circuit was designed using standard 555 timer configuration with resistors R1=3.3kΩ, R2=5.6kΩ and capacitor C1=100μF to control the pulse characteristics. The supply voltage was 9V DC. As per the design calculations, the circuit was expected to generate a 1Hz rectangular waveform with 61% duty cycle. The circuit was tested by observing the output waveform on an oscilloscope which matched closely with the designed values, validating the correct working of the implemented astable multivibrator. The active devices in the 555 timer IC generate the oscillations by alternately charging and discharging the timing capacitor based on certain voltage threshold levels, as set internally. Overall, through this work, a functional 555 timer based astable multivibrator was designed and its working was verified experimentally. Such multivibrator circuits find wide applications in timing controls, waveform generation, modulators, timers and other digital systems. The simple implementation makes it useful for learning and prototyping needs.
555 timer IC; Astable multivibrator; Oscilloscope; Square wave pulse; Transistors
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