RRB Technician Grade 1 Model Paper 4

Concept:A Schmitt trigger is a comparator circuit with positive feedback that converts any input waveform into a clean rectangular or square wave output.Explanation:The Schmitt trigger uses hysteresis with two threshold voltage levels: an upper threshold ($V_{UT}$) and a lower threshold ($V_{LT}$).When the input voltage rises above $V_{UT}$, the output switches to a high state ($V_{OH}$).When the input voltage falls below $V_{LT}$, the output switches to a low state ($V_{OL}$).If the input lies between $V_{UT}$ and $V_{LT}$, the output retains its previous value due to hysteresis.This dual-threshold action makes the circuit immune to noise and irregular input shapes.It can accept sinusoidal, triangular, or any arbitrary analog input signal.The output is always a rectangular (square) waveform regardless of the input shape, so it is also called a squaring circuit.Hence, a Schmitt trigger is mainly used for signal conditioning and waveform shaping in digital circuits.Answer:Option D: rectangular output for any type of input.