74121 Monostable Multivibrator with Schmitt-Trigger Input

The 74LS121 designed as a monostable Multi-vibrator with Schmitt-trigger inputs that feature dual negative-transition-triggered inputs. And a single positive-transition-triggered input that used as an inhibit input. 74LS121 IC operates at a wide range of working voltage, a wide range of working conditions. And directly interfaces with CMOS, NMOS, and TTL. The output of the IC always comes in TTL which makes it quite easy to function with other TTL devices and microcontrollers. Moreover, this IC 74LS121 comes as smaller in size and offers much faster speed. Thus makes it highly reliable in every kind of device.

A monostable multivibrator (MMV), also referred as a one-shot multivibrator. It is a pulse generator circuit in which the duration of the pulse determined by the R-C network, connected externally to the 555 timers. In such a vibrator, one state of output remains stable while the other is in quasi-stable (unstable). For auto-triggering of output from a quasi-stable state to a stable state, energy stored by an externally connected capaci­tor to a reference level. The time taken in storage determines the pulse width.

A Schmitt Trigger designed as a comparator-based circuit that gives the output on the basis of the previous gate output. In a Schmitt Trigger, the input value exist as analog or digital but output always comes in two forms 1 or 0.  By applying a positive feedback system, any circuit is convertible to Schmitt trigger. Meanwhile, in a Schmitt Trigger circuit, the threshold  used to obtain the output. When the value is greater than the threshold the output remain HIGH. Otherwise it will be considered in the LOW state. 

Applications

• Monostable multivibrators used as timers, delay circuits, gated circuits, etc