Astable Multivibrator Using 555 Timer Theory. Initially when the output is high capacitor c starts charging towards v cc through r a and r b. However as soon as the voltage across the capacitor equals 2 3 v cc comparator1 triggers the flip flop and the output switches to low state.
The oscillation frequency can be measured manually by small modification. Multivibrator is considered as a non sinusoidal oscillator which can generate waveforms other than sine wave. A monostable multivibrator mmv often called a one shot multivibrator is a pulse generator circuit in which the duration of the pulse is determined by the r c network connected externally to the 555 timer.
In this 555 astable multivibrator circuit led will switch on and off automatically with a particular duration.
You can find a lot of circuits and applications using astable mode in 555 timer circuits. On time off time frequency etc can be calculated using above formulas. The designing and working of astable multivibrator using a 555 timer ic is done by using ransistors and operational amplifiers. The above figure shows the 555 timer connected as an astable multivibrator.
