Question 1 |

Consider the OP AMP based circuit shown in the figure. Ignore the conduction drops of diodes D_{1} and D_{2}. All the components are ideal and the breakdown voltage of the Zener is 5 \mathrm{~V}. Which of the following statements is true?

The maximum and minimum values of the output voltage \mathrm{V}_{0} are +15 \mathrm{~V} and -10 \mathrm{~V}, respectively. | |

The maximum and minimum values of the output voltage \mathrm{V}_{0} are +5 \mathrm{~V} and -15 \mathrm{~V}, respectively. | |

The maximum and minimum values of the output voltage \mathrm{V}_{0} are +10 \mathrm{~V} and -5 \mathrm{~V}, respectively. | |

The maximum and minimum values of the output voltage \mathrm{V}_{0} are +5 \mathrm{~V} and -10V, respectively |

Question 1 Explanation:

During positive hall cycle:

\therefore \mathrm{D}_{1} \rightarrow \mathrm{ON} and \mathrm{D}_{2} \rightarrow \mathrm{OFF}

Redraw the circuit :

\therefore V_0=-V_i

\quad (V_0)_{min}=-10V

During negative half cycle :

\mathrm{V}^{+} \gt \mathrm{V}^{-}

Zener diode \rightarrow ON, \mathrm{D}_{1} \rightarrow OFF and \mathrm{D}_{2} \rightarrow \mathrm{ON}

Redraw the circuit:

\therefore \quad (V_0)_{max}=5V

\therefore \mathrm{D}_{1} \rightarrow \mathrm{ON} and \mathrm{D}_{2} \rightarrow \mathrm{OFF}

Redraw the circuit :

\therefore V_0=-V_i

\quad (V_0)_{min}=-10V

During negative half cycle :

\mathrm{V}^{+} \gt \mathrm{V}^{-}

Zener diode \rightarrow ON, \mathrm{D}_{1} \rightarrow OFF and \mathrm{D}_{2} \rightarrow \mathrm{ON}

Redraw the circuit:

\therefore \quad (V_0)_{max}=5V

Question 2 |

Two monoshot multivibrators, one positive edge triggered (M_{1}) and another negative edge triggered (M_{2}), are connected as shown in figure

The monoshots (M_{1}) and (M_{2}) when triggered produce pulses of width (T_{1}) and (T_{2}) respectively, where (T_{1} \gt T_2) . The steady state output voltage (v_{o}) of the circuit is

The monoshots (M_{1}) and (M_{2}) when triggered produce pulses of width (T_{1}) and (T_{2}) respectively, where (T_{1} \gt T_2) . The steady state output voltage (v_{o}) of the circuit is

A | |

B | |

C | |

D |

Question 2 Explanation:

Not in the GATE-2018 Syllabus.

Question 3 |

The following circuit has a source voltage V_s as shown in the graph. The current
through the circuit is also shown.

The element connected between a and b could be

The element connected between a and b could be

A | |

B | |

C | |

D |

Question 3 Explanation:

Diode act as a switch. When forward biased it is short circuited. But when suddenly reverse biased, current does not become zero instantly , initially the same current flow in opposite direction and after some time (turn off time) it will become zero.

Question 4 |

The truth table of monoshot shown in the figure is given in the table below :

Two monoshots, one positive edge triggered and other negative edge triggered, are connected shown in the figure, The pulse widths of the two monoshot outputs Q_1 \; and \; Q_2 are T_{ON1} and T_{ON2} respectively.

The frequency and the duty cycle of the signal at Q_1 will respectively be

Two monoshots, one positive edge triggered and other negative edge triggered, are connected shown in the figure, The pulse widths of the two monoshot outputs Q_1 \; and \; Q_2 are T_{ON1} and T_{ON2} respectively.

The frequency and the duty cycle of the signal at Q_1 will respectively be

f=\frac{1}{T_{ON_{1}}+T_{ON_{2}}},D=\frac{T_{ON_{1}}}{T_{ON_{1}}+T_{ON_{2}}} | |

f=\frac{1}{T_{ON_{1}}+T_{ON_{2}}},D=\frac{T_{ON_{2}}}{T_{ON_{1}}+T_{ON_{2}}} | |

f=\frac{1}{T_{ON_{1}}},D=\frac{T_{ON_{1}}}{T_{ON_{1}}+T_{ON_{2}}} | |

f=\frac{1}{T_{ON_{2}}},D=\frac{T_{ON_{1}}}{T_{ON_{1}}+T_{ON_{2}}} |

Question 4 Explanation:

f=\frac{1}{T_{ON1}+T_{ON2}}, D=\frac{T_{ON1}}{T_{ON1}+T_{ON2}}

Question 5 |

IC 555 in the adjacent figure is configured as an astable multi-vibrator. It is
enabled to to oscillate at t=0 by applying a high input to pin 4.

The pin description is :

1 and 8-supply;

2-trigger;

4-reset;

6-threshold

7-discharge.

The waveform appearing across the capacitor starting from t=0, as observed on a storage CRO is

The pin description is :

1 and 8-supply;

2-trigger;

4-reset;

6-threshold

7-discharge.

The waveform appearing across the capacitor starting from t=0, as observed on a storage CRO is

A | |

B | |

C | |

D |

Question 5 Explanation:

An astable multi-vibrator is providing pulse as given below

But in this case initial voltage at capacitor is zero. So it starts from zero. Also charging time will be larger (normally) than discharging time but it is made equal by using a diode.

But in this case initial voltage at capacitor is zero. So it starts from zero. Also charging time will be larger (normally) than discharging time but it is made equal by using a diode.

There are 5 questions to complete.