Question

1. Illustrate   IC 555 timer as Monostable Multivibrator   and Astable Multivibrator                  

Answer 1

A monostable multivibrator (MMV) is also called as one-shot multivibrator is a pulse generator circuit in which the duration of pulse is determined by r-c network, connected externally to the 555 timer

One state of output is stable while the other is quasi-stable(unstable) for auto triggering of output from quasi-stable State to stable State energy is stored by externally connected capacitor 'c' to a reference level.

The time taken in storage determined pulse width . The transistor of output from stable State to quasi-stable State is accomplished by external triggeringtpin 1 is grounded . triggering input is applied to pin 2 .in quiescent condition of output this input is kept at +VCC.To obtain transition of output from stable State to quasi-stable State,a negative-going pulse of narrow width and amplitude of greater than +2/3VCC to avoid accidental to pin 2 output is taken from pin 3 pin 4 is usually connect to +VCC.pin 5 is grout through a0.01uf capacitor to avoid noise .Pin 6 is shorted to pin 7 a discharge capacitor is connected while pin 8 is connected to supply