schmitt trigger practical viva question

[jaseela123d]

In electronics, a Schmitt trigger is a comparator circuit with hysteresis implemented by applying positive feedback to the non-inverting input of a comparator or differential amplifier. It is an active circuit that converts an analog input signal into a digital output signal. The circuit is called a "trigger" because the output retains its value until the input changes enough to trigger a change. In the non-inverting configuration, when the input is higher than a chosen threshold, the output is high. When the input is below a different (lower) threshold chosen, the output is low and when the input is between the two levels, the output retains its value. This double-threshold action is called hysteresis and implies that the Schmitt trigger has memory and can act as a bistable multivibrator (closure or flip-flop). There is a close relationship between the two types of circuits: a Schmitt trigger can become a deadbolt and a deadbolt can become a Schmitt trigger. Schmitt firing devices are typically used in signal conditioning applications to eliminate noise from the signals used in digital circuits, particularly mechanical bounce contact. They are also used in closed loop negative feedback configurations to implement relaxation oscillators, used in function generators and switching power supplies.


The Schmitt trigger was invented by American scientist Otto H. Schmitt in 1934, while he was a graduate student, later described in his doctoral dissertation (1937) as a "thermionic trigger." It was a direct result of Schmitt's study on the propagation of the neural impulse in the squid nerves.