Oscillators Question & Answers June 5, 2021 By WatElectronics This article lists 100+ oscillators MCQs for engineering students. All the oscillators Questions & Answers given below include a hint and wherever possible link to the relevant topic. This is helpful for the users who are preparing for their exams, interviews, or professionals who would like to brush up their fundamentals on the oscillators topic. Oscillators are devices known for converting the signals DC into AC. Any amplifier can be converted to an oscillator by giving a feedback connection. An amplifier for amplification prefers negative feedback and provided with positive feedback results in oscillations. The signal produced at the output is continuous it can be a sine wave, square wave, or triangular wave. Based on frequency these oscillators are classified as Low-frequency oscillators, Audio frequency oscillators, and Radiofrequency oscillators. The two main classifications of oscillators are Harmonic or linear oscillators and Relaxation or non-linear oscillators. They are used in Clock generators, Calculators, other complex peripherals, and so on. 1). What is the very first practical oscillator based on? Electric arcs Feedback Frequency Linearity Hint 2). Oscillator circuit built by _______________. Humphry Davy Benjamin Silliman Elihu Thomson Ernst Lecher Hint 3). Parametric oscillator circuit is developed by ________. Humphry Davy Benjamin Silliman Elihu Thomson George Francis FitzGerald Hint 4). Arc oscillator rediscovered by _____________. Humphry Davy Benjamin Silliman William Duddell Elihu Thomson Hint 5). Vacuum-tube Feedback Oscillators were invented in ___________. 1912 1913 1914 1915 Hint 6). Edwin Armstrong preferred ______________feedback. Positive Negative Both a & b None of the above Hint 7). _______________ converts Direct Current (DC) signals available from the power supply units to Alternate Current (AC) signals. Micro-controllers Oscillators Transformer Relays Hint 8). A _________ criterion determines mathematical condition to obtain sustained oscillations. Pythagorous Abel-Jacobi Barkhausen None of the above Hint 9). What are the types of oscillators based on frequency as the parameter? Low frequency oscillators Audio oscillators Radiofrequency oscillators All the above Hint 10). The _____________ feedback is used in oscillators. Positive Negative Neither negative nor positive None of the above Hint 11). Which of the oscillators doesn’t come under the category of low frequency oscillators? RC phase shift oscillator Wien bridge oscillator Twin T oscillators Crystal oscillator Hint 12). Both negative and the positive feedback is present in _______ oscillator. RC phase shift oscillator Wien bridge oscillator Twin T oscillators Crystal oscillator Hint 13). The filter in the RC oscillator circuit consists of ___________. Inductors Resistors Capacitors Both b & c Hint 14). Which of these oscillators doesn’t consists of LC tank circuit? Colpitts oscillator Hartley oscillator Clapps oscillator Wien bridge oscillator Hint 15). Positive feedback results in ___________ oscillations. Damped Undamped Modulated None of the above Hint 16) .Microprocessors uses _________ oscillators. RC phase shift oscillator Wien bridge oscillator Twin T oscillators Crystal oscillator Hint 17). UJT is a ____________ oscillator. Wien bridge Feedback Relaxation None of the above Hint 18). The very first and the mostly used circuit of Relaxation oscillator is __________. Astable Multivibrator Bistable Multivibrator Monostable Multivibrator Multiplexer Hint 19). __________ Circuits are the base for the design of contemporary microwave oscillators. Positive-resistance Zero resistance Negative- resistance Both a & b Hint 20). Multivibrators comes under the category of ___________ oscillators. Sinusoidal Square wave Ramp Triangular wave Hint 21). Non-sinusoidal oscillators are _____________. Multivibrators Square wave oscillators Hartley oscillators Both a & b Hint 22). The frequency in the LC oscillator is ____________. Proportional to the square root of L or C Directly proportional to L or C Inversely proportional to the square root of L or C. Independent of L or C Hint 23). Which is the most stable oscillator? RC phase shift oscillator Wien bridge oscillator Twin T oscillators Crystal oscillator Hint 24). If the value of capacitor is at maximum in LC tank circuit, the energy at the inductor is ____________. Maximum Minimum Either maximum or minimum None of the above Hint 25). Hartley oscillator consists of ________ inductors. One Two Three Four Hint Oscillator MCQs for Interview 26). The phase shift obtained at the feedbacks loop is ____________ degrees. 0 180 270 90 Hint 27). Theoretically the gain in the oscillator must be equal to _______. High Low Unity None of the above Hint 28). Which oscillator used to generate 1 Mega hertz signal? RC phase shift oscillator Wien bridge oscillator Twin T oscillators Hartley oscillator Hint 29). Which oscillators are preferred in the Timing elements? RC phase shift oscillator Wien bridge oscillator Crystal oscillators Hartley oscillator Hint 30). Hartley oscillator has ________ capacitors in its Tank circuit. One Two Three Four Hint 31). Operating range of frequency of Hartley oscillators is _____________. 20 KHz to 20 MHz 30 KHz to 30 MHz 40 KHz to 40 MHz None of the above Hint 32). How many capacitors are present in Colpitts oscillator? One Two Three Four Hint 33). Additional capacitor in series with the inductor is placed in which oscillator? RC phase shift oscillator Clapp oscillator Crystal oscillators Hartley oscillator Hint 34). The flow of energy is unidirectional in which oscillators? Harmonic oscillators Relaxation oscillators Both a and b None of the above Hint 35). In which oscillators the energy can be exchanged between passive and the active components? Harmonic oscillators Relaxation oscillators Both a and b None of the above Hint 36). The oscillations frequency in harmonic oscillator can be determined by ______________. Feedback path Charging of time constants Discharging of time constants Both b and d Hint 37). Oscillations frequency of relaxation oscillators can be determined by ___________. Feedback path Charging of time constants Discharging of time constants Both b and d Hint 38). Harmonic oscillators generate _______ waveforms as output. Saw tooth Square Triangular Sinusoidal Hint 39). Relaxation oscillators generate _______ waveforms as output. Saw tooth Square Triangular All the above Hint 40). The device active in the LC oscillator of transistor is _________. Tank circuit Bias circuit Transistor All the above Hint 41). The drawback of LC oscillators are _____________. Instability of frequency Poor waveforms Cannot be preferred for low frequencies All the above Hint 42). Inductors used in LC oscillators makes the circuit bulky and ____________. Expensive Cheap Moderate None of the above Hint 43). RC oscillators are also known as __________________ Phase shift oscillators Clapp oscillator Crystal oscillators Hartley oscillator Hint 44). Total phase shift in the RC oscillators is _______. 0 180 270 90 Hint 45). The frequency in the Phase shift oscillators can be determined by __________ components. Inductors Capacitors Resistors Both b and c Hint 46). Which oscillators has fixed set of frequencies? RC phase shift oscillator Clapp oscillator Crystal oscillators Hartley oscillator Hint 47). What is the reason of failure of Crystal oscillators? Instability of frequency Poor waveforms Cannot be preferred for low frequencies Overheating Hint 48). The Q factor of the Crystal oscillator is ____________. High Low Moderate None of the above Hint 49). The network of RC in the Wien bridge oscillators is known as ___________. Lead network Lag network Lead-Lag network None of the above Hint 50). The increase in the frequency makes the phase-shift ____________ in the Wien bridge oscillator. Lead Lag Lead-Lag None of the above Hint Oscillator Multiple Choice Question and Answers 51). The decrease in the frequency makes the phase-shift ___________ in the Wien bridge oscillator. Lead Lag Lead-Lag None of the above Hint 52). How many RC networks present in Twin-T oscillators? One Two Three Four Hint 53). Feedback in the colpitts oscillator is by __________ component. Resistor Inductor Capacitor Transformer Hint 54). Tank circuits in Colpitts oscillator possess ________ capacitors. One Two Three Four Hint 55). Improved performance of Colpitts oscillator in comparison to the Hartley oscillator is because of _________ components. Resistor Inductor Capacitor Transformer Hint 56). Gain device of Colpitts oscillators behaves as _______ filter. Low pass High pass Band pass Band reject Hint 57). Which feedback is present in Colpitts oscillator? Positive Negative Both positive and negative None of the above Hint 58). What is the active element of the Colpitts oscillator? Diode Transformer Transistor All the above Hint 59). The circuit of Colpitts oscillator is capacitive and improves the __________. Impedance Stability of frequency Both a and b None of the above Hint 60). Oscillations classified as sustained and damped based on ___________. Power Noise Frequency Amplitude Hint 61). Colpitts oscillator’s frequency is ________. 1/2π√LCt 1/3π√LCt 1/4π√LCt 1/5π√LCt Hint 62). For the feedback component used in Hartley oscillators are _____________. Resistors Inductors Capacitors Transformer Hint 63). Number of capacitors in Hartley oscillator is _______. One Two Three Four Hint 64). Number of inductors in Hartley oscillators are _________. One Two Three Four Hint 65). Difference between Hartley and the Colpitts oscillators is _________. Frequency Power supply Feedback across different components Both a and b Hint 66). Self-limiting oscillators are ___________. RC phase-shift oscillators Multivibrators Relaxation oscillators LC oscillators Hint 67). The voltage divided in the Clapps oscillator is due to _________. Resistors Inductors Capacitors Transformer Hint 68). Which effect is present in Crystal oscillators? Triboelectric effect Piezoelectric effect Both a and b None of the above Hint 69). Threshold voltage is pre-determined in ______________. RC phase-shift oscillators Multivibrators Relaxation oscillators LC oscillators Hint 70). Relaxation oscillator made up of op-amp circuit is referred to as ____________. Astable Multivibrator Monostable Multivibrator Bistable Multivibrator None of the above Hint 71). Relaxation oscillator’s op-amp circuit generates ________ signal. Sawtooth Square wave Ramp Triangular Hint 72). Possibility of signaling of internal clock in the digital circuits is by ____________. RC phase-shift oscillators Multivibrators Relaxation oscillators LC oscillators Hint 73). VCO stands for ________________. Voltage-controlled oscillator Value controlled oscillations Voltage counter operations None of the above Hint 74). The frequency of oscillations in the VCO is controlled by __________. Power Current Input voltage All the above Hint 75). Phase-shift at the tank circuit of Hartley oscillators is ____________ degrees. 0 90 180 270 Hint Oscillators Important Questions with Answers 76). An LC circuit in the oscillator is known as ____________. Resonant circuit Tank circuit Tuned circuit All the above Hint 77). RFC stands for ______________. Radio Frequency Choke Radar Frequency Communication Radio Frequency Communication None of the above Hint 78). Clapp Oscillator preferred above __________ for the construction of Variable frequency oscillators. RC phase shift oscillator Colpitts oscillator Crystal oscillators Hartley oscillator Hint 79). How many capacitors are present in the Clapp oscillators? One Two Three Four Hint 80). Which type of feedback is present in Clapp oscillators? Positive Negative Both Positive and Negative None of the above Hint 81). The amount or the value of the feedback applied as the input at transistor is determined by ________ in the Clapp oscillators. Power supply Noise Voltage divider All the above Hint 82). _____________ oscillator has the constant frequency in the output. RC phase shift oscillator Clapp oscillator Crystal oscillators Hartley oscillator Hint 83). If there is no signal at input applied what triggers the operation of oscillators? Temperature Pressure DC Noise voltage Hint 84). Harmonic oscillators are ________. Sinusoidal oscillators Non-sinusoidal oscillators Both a and b Relaxation oscillators Hint 85).Which of these is not considered as non-sinusoidal oscillators? Multivibrators Blocking oscillators Crystal oscillators None of the above Hint 86). If the value of capacitor is tends to be maximum the energy at the inductor reaches ___________ in LC oscillators. Minimum Maximum Undetermined Data insufficient Hint 87). If the frequency of the crystal tends to change with temperature, the crystal is said to have __________ coefficient of temperature. Zero Positive Negative Undetermined Hint 88). Basic difference between oscillators and amplifiers is ___________. High gain Frequency stability No input signal needed No Dc supply Hint 89). What is the limitation of Crystal oscillator? Low output High Q High output Cannot say Hint 90). Ocxo is an acronym for ___________. Oven Controlled Crystal Oscillator Output Controlled Crystal oscillator Output Compensated Crystal Oscillator None of the above Hint 91). Which oscillator is known as Meissner oscillator? RC phase shift oscillator Clapp oscillator Crystal oscillators Armstrong oscillator Hint 92). __________ oscillators have transformer coupling. RC phase shift oscillator Clapp oscillator Crystal oscillators Armstrong oscillator Hint 93). Practically a circuit for triangular-wave is a combination of __________. Comparator and Inductor Comparator and Integrator Capacitor and Inductor Capacitor and Integrator Hint 94). __________ oscillators frequency gets varied by varying DC control voltage. RC phase shift oscillator Clapp oscillator Voltage Controlled oscillators Armstrong oscillator Hint 95). Crystal oscillators are mostly found in ___________. Radio receivers Radio transmitters Square generators None of the above Hint 96). A GPS unit uses __________ oscillators. Phase-shift oscillators Multivibrators Relaxation oscillators LC oscillators Hint 97). Radio receivers use ___________ oscillators. RC phase shift Clapp Crystal Hartley Hint 98). Phase-Locked loop (PLL) uses ________ oscillators. RC phase-shift oscillators Multivibrators Relaxation oscillators Voltage-Controlled oscillators Hint 99). Digital systems prefer _____________ oscillators. RC phase shift Clapp Crystal Hartley Hint 100). The signal generators utilized in the general laboratories are _______ oscillators. RC phase shift oscillator Wien bridge oscillator Crystal oscillators Hartley oscillator Hint 101). 555 Timer consists of ________. Two comparators Flip-flop Discharge transistor All the above Hint 102). The crystal in crystal oscillator acts as __________. Filter Power source Resonant circuit Both b & c Hint Read More About Colpitts Oscillator Time is Up! Time's up