Monostable Multivibrator Using 555 Timer Output Waveforms. 4 th pin is the reset pin of 555 timer which is active low so it is connected to vcc to avoid accidental resets. Using the 555 timer the duration of such pulses can be varied from tens of µs to hours.
When the ic 555 is used as a monostable multivibrator a positive going rectangular pulse is available at the output when a negative going pulse of short duration is applied at the trigger input. 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. 5 th pin is the control voltage pin used to provide external reference voltage to internal comparators.
In a stable or standby state the output of the circuit is approximately zero or a logic low level.
For auto triggering of output from quasi stable state to stable state energy is stored by an externally connected capaci tor c to a reference level. For auto triggering of output from quasi stable state to stable state energy is stored by an externally connected capaci tor c to a reference level. 555 timer circuit as monostable multivibrator figure shows the circuit diagram of monostable multivibrator using a 555 timer ic. If the output is low application of a negative going pulse to the traigger input sets the flip flop q goes low drives the output high and turns off q 1.
