OP AMP BASED MONOSTABLE MULTIVIBRATOR 741

CIRCUIT DIAGRAM OF OP AMP BASED MONOSTABLE MULTIVIBRATOR (741 IC)

MONOSTABLE MULTIVIBRATOR USING OP AMP 741

Monostable multivibrator is also called as One Shot Multivibrator. It has a Stable State and a Quasi-Stable State. The circuit remains in stable state until a triggering signal is applied to its input. After getting the triggering signal the output transit from stable to Quasi-stable state and return back after a time period. So a Single Pulse is generated for single Trigger.

Consider the instant at which the output Vo=+Vsat. At that time diode D1 damps the Capacitor voltage, Vc at 0.7V. Feedback voltage is +βVsat at Non-Inverting terminal. When the negative trigger is applied, the potential at Non-Inverting terminal becomes less than 0.7v the output switches to -Vsat, which makes the diode more negative than -βVsat. Comparator switches back to +Vsat. The Capacitor C starts charging to +Vsat through R until Vc reaches 0.7v and C becomes damped to 0.7v.

The pulse width is given by T=RC*ln(1/1-β).

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