Oscillators Question & AnswersJune 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 arcsFeedbackFrequencyLinearityHint Electric arcs were utilized for lighting 2). Oscillator circuit built by _______________.Humphry DavyBenjamin SillimanElihu ThomsonErnst LecherHintOscillator circuit in the year 1892 3). Parametric oscillator circuit is developed by ________.Humphry DavyBenjamin SillimanElihu ThomsonGeorge Francis FitzGeraldHintGeorge Francis FitzGerald realized if the resistance in the resonance circuit is either made to zero or else negative 4). Arc oscillator rediscovered by _____________.Humphry DavyBenjamin SillimanWilliam DuddellElihu ThomsonHintWilliam Duddell made popular the rediscovered Arc oscillator 5). Vacuum-tube Feedback Oscillators were invented in ___________.1912191319141915HintAudion an electronic amplifying or detecting vacuum tube 6). Edwin Armstrong preferred ______________feedback.PositiveNegativeBoth a & bNone of the aboveHintRegenerative receivers 7). _______________ converts Direct Current (DC) signals available from the power supply units to Alternate Current (AC) signals.Micro-controllersOscillatorsTransformerRelaysHintOscillator accepts DC voltages and generates periodic waveform 8). A _________ criterion determines mathematical condition to obtain sustained oscillations.PythagorousAbel-JacobiBarkhausenNone of the aboveHintBarkhausen criterion determines 9). What are the types of oscillators based on frequency as the parameter?Low frequency oscillatorsAudio oscillatorsRadiofrequency oscillatorsAll the aboveHintLFO and HFO 10). The _____________ feedback is used in oscillators.PositiveNegativeNeither negative nor positiveNone of the aboveHintPositive feedback gives the highest gain 11). Which of the oscillators doesn’t come under the category of low frequency oscillators?RC phase shift oscillatorWien bridge oscillatorTwin T oscillatorsCrystal oscillatorHintCrystal oscillators operate at high frequencies 12). Both negative and the positive feedback is present in _______ oscillator.RC phase shift oscillatorWien bridge oscillatorTwin T oscillatorsCrystal oscillatorHintTwo transistors are present in Wien bridge oscillators 13). The filter in the RC oscillator circuit consists of ___________.InductorsResistorsCapacitorsBoth b & cHintLow-frequency oscillators 14). Which of these oscillators doesn’t consists of LC tank circuit?Colpitts oscillatorHartley oscillatorClapps oscillatorWien bridge oscillatorHintWien bridge oscillator consists of resistors and capacitors 15). Positive feedback results in ___________ oscillations.DampedUndampedModulatedNone of the aboveHintOscillations with constant amplitude and time 16) .Microprocessors uses _________ oscillators.RC phase shift oscillatorWien bridge oscillatorTwin T oscillatorsCrystal oscillatorHintProcessing of high-speed data 17). UJT is a ____________ oscillator.Wien bridgeFeedbackRelaxationNone of the aboveHintUJT produces non-sinusoidal waveform 18). The very first and the mostly used circuit of Relaxation oscillator is __________.Astable MultivibratorBistable MultivibratorMonostable MultivibratorMultiplexerHintAstable multivibrator was discovered by French Engineers 19). __________ Circuits are the base for the design of contemporary microwave oscillators.Positive-resistanceZero resistanceNegative- resistanceBoth a & bHintK. Kurokawa is the person to determine 20). Multivibrators comes under the category of ___________ oscillators.SinusoidalSquare waveRampTriangular waveHintMultivibrators produces square wave as the output 21). Non-sinusoidal oscillators are _____________.MultivibratorsSquare wave oscillatorsHartley oscillatorsBoth a & bHintRelaxation oscillator 22). The frequency in the LC oscillator is ____________.Proportional to the square root of L or CDirectly proportional to L or CInversely proportional to the square root of L or C.Independent of L or CHintHigher frequencies 23). Which is the most stable oscillator?RC phase shift oscillatorWien bridge oscillatorTwin T oscillatorsCrystal oscillatorHintStable frequencies can be generated using Crystal oscillators 24). If the value of capacitor is at maximum in LC tank circuit, the energy at the inductor is ____________.MaximumMinimumEither maximum or minimumNone of the aboveHintCapacitor and the energy at the inductor are inversely proportional 25). Hartley oscillator consists of ________ inductors.OneTwoThreeFourHintTwo inductors are connected in series and parallelOscillator MCQs for Interview 26). The phase shift obtained at the feedbacks loop is ____________ degrees.018027090HintSustained oscillations 27). Theoretically the gain in the oscillator must be equal to _______.HighLowUnityNone of the aboveHintGain must be slightly greater than 1 28). Which oscillator used to generate 1 Mega hertz signal?RC phase shift oscillatorWien bridge oscillatorTwin T oscillatorsHartley oscillatorHintLC circuit 29). Which oscillators are preferred in the Timing elements?RC phase shift oscillatorWien bridge oscillatorCrystal oscillatorsHartley oscillatorHintOscillators have the highest stability of frequency 30). Hartley oscillator has ________ capacitors in its Tank circuit.OneTwoThreeFourHintOne capacitor and two inductors 31). Operating range of frequency of Hartley oscillators is _____________.20 KHz to 20 MHz30 KHz to 30 MHz40 KHz to 40 MHzNone of the aboveHintRealized by using Op-amps, FET, or BJT. 32). How many capacitors are present in Colpitts oscillator?OneTwoThreeFourHintTwo capacitors are in series 33). Additional capacitor in series with the inductor is placed in which oscillator?RC phase shift oscillatorClapp oscillatorCrystal oscillatorsHartley oscillatorHintFrequency stability 34). The flow of energy is unidirectional in which oscillators?Harmonic oscillatorsRelaxation oscillatorsBoth a and bNone of the aboveHintHarmonic oscillators possess a unidirectional flow of energy 35). In which oscillators the energy can be exchanged between passive and the active components?Harmonic oscillatorsRelaxation oscillatorsBoth a and bNone of the aboveHintRelaxation oscillators are capable of exchanging the flow of energy 36). The oscillations frequency in harmonic oscillator can be determined by ______________.Feedback pathCharging of time constantsDischarging of time constantsBoth b and dHintHarmonic oscillators are also known as Feedback oscillators 37). Oscillations frequency of relaxation oscillators can be determined by ___________.Feedback pathCharging of time constantsDischarging of time constantsBoth b and dHintOscillation frequency depends upon the charging and discharging 38). Harmonic oscillators generate _______ waveforms as output.Saw toothSquareTriangularSinusoidalHintLow-distorted sinusoidal waveforms 39). Relaxation oscillators generate _______ waveforms as output.Saw toothSquareTriangularAll the aboveHintNon-sinusoidal signals 40). The device active in the LC oscillator of transistor is _________.Tank circuitBias circuitTransistorAll the aboveHintTransistor in the oscillator 41). The drawback of LC oscillators are _____________.Instability of frequencyPoor waveformsCannot be preferred for low frequenciesAll the aboveHintRC oscillators 42). Inductors used in LC oscillators makes the circuit bulky and ____________.ExpensiveCheapModerateNone of the aboveHintExpensive due to inductors 43). RC oscillators are also known as __________________Phase shift oscillatorsClapp oscillatorCrystal oscillatorsHartley oscillatorHintOutput sine signal generated is based on the phase shift 44). Total phase shift in the RC oscillators is _______.018027090HintEach section of RC produces 60 degrees 45). The frequency in the Phase shift oscillators can be determined by __________ components.InductorsCapacitorsResistorsBoth b and cHintResistors and capacitors present to determine the frequency 46). Which oscillators has fixed set of frequencies?RC phase shift oscillatorClapp oscillatorCrystal oscillatorsHartley oscillatorHintHybrid clock 47). What is the reason of failure of Crystal oscillators?Instability of frequencyPoor waveformsCannot be preferred for low frequenciesOverheatingHintCrystal oscillators consist of materials made of Piezo 48). The Q factor of the Crystal oscillator is ____________.HighLowModerateNone of the aboveHintUnder damped 49). The network of RC in the Wien bridge oscillators is known as ___________.Lead networkLag networkLead-Lag networkNone of the aboveHintPhase-shift present in the network 50). The increase in the frequency makes the phase-shift ____________ in the Wien bridge oscillator.LeadLagLead-LagNone of the aboveHintIncreased frequencyOscillator Multiple Choice Question and Answers 51). The decrease in the frequency makes the phase-shift ___________ in the Wien bridge oscillator.LeadLagLead-LagNone of the aboveHintPhase shift tends to lead 52). How many RC networks present in Twin-T oscillators?OneTwoThreeFourHintTwo RC networks 53). Feedback in the colpitts oscillator is by __________ component.ResistorInductorCapacitorTransformerHintVoltage divider in the LC circuit 54). Tank circuits in Colpitts oscillator possess ________ capacitors.OneTwoThreeFourHintTwo capacitors present in the LC circuit 55). Improved performance of Colpitts oscillator in comparison to the Hartley oscillator is because of _________ components.ResistorInductorCapacitorTransformerHintCapacitive elements in the Colpitts oscillator 56). Gain device of Colpitts oscillators behaves as _______ filter.Low passHigh passBand passBand rejectHintOscillation frequencies are limited to certain ranges 57). Which feedback is present in Colpitts oscillator?PositiveNegativeBoth positive and negativeNone of the aboveHint To satisfy the Barkhausen condition 58). What is the active element of the Colpitts oscillator?DiodeTransformerTransistorAll the aboveHintAmplify the weak signals transistor is used 59). The circuit of Colpitts oscillator is capacitive and improves the __________.ImpedanceStability of frequencyBoth a and bNone of the aboveHintFrequency stability 60). Oscillations classified as sustained and damped based on ___________.PowerNoiseFrequencyAmplitudeHintVariations in amplitude 61). Colpitts oscillator’s frequency is ________.1/2π√LCt1/3π√LCt1/4π√LCt1/5π√LCtHintCt determines the equivalence capacitance 62). For the feedback component used in Hartley oscillators are _____________.ResistorsInductorsCapacitorsTransformerHintInductors in the Hartley oscillators 63). Number of capacitors in Hartley oscillator is _______.OneTwoThreeFourHintHartley oscillator consists of one capacitor 64). Number of inductors in Hartley oscillators are _________.OneTwoThreeFourHintTwo inductors are present in the Hartley oscillator's 65). Difference between Hartley and the Colpitts oscillators is _________.FrequencyPower supplyFeedback across different componentsBoth a and bHintFeedback 66). Self-limiting oscillators are ___________.RC phase-shift oscillatorsMultivibratorsRelaxation oscillatorsLC oscillatorsHintTank circuit 67). The voltage divided in the Clapps oscillator is due to _________.ResistorsInductorsCapacitorsTransformerHintModified version of the Colpitts oscillators 68). Which effect is present in Crystal oscillators?Triboelectric effectPiezoelectric effectBoth a and bNone of the aboveHintPiezo 69). Threshold voltage is pre-determined in ______________.RC phase-shift oscillatorsMultivibratorsRelaxation oscillatorsLC oscillatorsHintCapacitors present in Relaxation oscillators 70). Relaxation oscillator made up of op-amp circuit is referred to as ____________.Astable MultivibratorMonostable MultivibratorBistable MultivibratorNone of the aboveHintAstable multivibrator possesses two states 71). Relaxation oscillator’s op-amp circuit generates ________ signal.SawtoothSquare waveRampTriangularHintSignal undergoes a transition between two states 72). Possibility of signaling of internal clock in the digital circuits is by ____________.RC phase-shift oscillatorsMultivibratorsRelaxation oscillatorsLC oscillatorsHintFor internal signaling of clocks in the circuits relaxation oscillators are used 73). VCO stands for ________________.Voltage-controlled oscillatorValue controlled oscillationsVoltage counter operationsNone of the aboveHintThe applied value of the voltage at the input is determined by the frequency of oscillations in the voltage-controlled oscillators. 74). The frequency of oscillations in the VCO is controlled by __________.PowerCurrentInput voltageAll the aboveHintInput voltage controls the frequency of oscillations 75). Phase-shift at the tank circuit of Hartley oscillators is ____________ degrees.090180270HintMeet the Barkhausen criteriaOscillators Important Questions with Answers 76). An LC circuit in the oscillator is known as ____________.Resonant circuitTank circuitTuned circuitAll the aboveHintInductor represented as L and the capacitor represented as C 77). RFC stands for ______________.Radio Frequency ChokeRadar Frequency CommunicationRadio Frequency CommunicationNone of the aboveHintRadiofrequency choke at the collector provides higher reactance 78). Clapp Oscillator preferred above __________ for the construction of Variable frequency oscillators.RC phase shift oscillatorColpitts oscillatorCrystal oscillatorsHartley oscillatorHintTuning circuits present at receivers 79). How many capacitors are present in the Clapp oscillators?OneTwoThreeFourHintVoltage divider circuit in the Clapp oscillator 80). Which type of feedback is present in Clapp oscillators?PositiveNegativeBoth Positive and NegativeNone of the aboveHint Positive feedback is preferred 81). The amount or the value of the feedback applied as the input at transistor is determined by ________ in the Clapp oscillators.Power supplyNoiseVoltage dividerAll the aboveHintVoltage divider circuit formed with three capacitors 82). _____________ oscillator has the constant frequency in the output.RC phase shift oscillatorClapp oscillatorCrystal oscillatorsHartley oscillatorHintCrystal oscillator's main feature is the constant frequency 83). If there is no signal at input applied what triggers the operation of oscillators?TemperaturePressureDCNoise voltageHintPresence of noise voltage 84). Harmonic oscillators are ________.Sinusoidal oscillatorsNon-sinusoidal oscillatorsBoth a and bRelaxation oscillatorsHintGenerates sinusoidal waves 85).Which of these is not considered as non-sinusoidal oscillators?MultivibratorsBlocking oscillatorsCrystal oscillatorsNone of the aboveHintSinusoidal oscillators 86). If the value of capacitor is tends to be maximum the energy at the inductor reaches ___________ in LC oscillators.MinimumMaximumUndeterminedData insufficientHintCapacitor value and the inductor energy are inversely proportional 87). If the frequency of the crystal tends to change with temperature, the crystal is said to have __________ coefficient of temperature.ZeroPositiveNegativeUndeterminedHintElectrical resistance increases with the increase in temperature 88). Basic difference between oscillators and amplifiers is ___________.High gainFrequency stabilityNo input signal neededNo Dc supplyHintWithout the application of input 89). What is the limitation of Crystal oscillator?Low outputHigh QHigh outputCannot sayHintLow output is the main limitation 90). Ocxo is an acronym for ___________.Oven Controlled Crystal OscillatorOutput Controlled Crystal oscillatorOutput Compensated Crystal OscillatorNone of the aboveHint The top-performing quartz Crystal oscillator 91). Which oscillator is known as Meissner oscillator?RC phase shift oscillatorClapp oscillatorCrystal oscillatorsArmstrong oscillatorHintArmstrong oscillator is an electronic oscillator 92). __________ oscillators have transformer coupling.RC phase shift oscillatorClapp oscillatorCrystal oscillatorsArmstrong oscillatorHintArmstrong oscillators are less popular 93). Practically a circuit for triangular-wave is a combination of __________.Comparator and InductorComparator and IntegratorCapacitor and InductorCapacitor and IntegratorHintTriangular wave generators use fast comparators 94). __________ oscillators frequency gets varied by varying DC control voltage.RC phase shift oscillatorClapp oscillatorVoltage Controlled oscillatorsArmstrong oscillatorHint Integrator used in VCO 95). Crystal oscillators are mostly found in ___________.Radio receiversRadio transmittersSquare generatorsNone of the aboveHintRadio transmitters 96). A GPS unit uses __________ oscillators.Phase-shift oscillatorsMultivibratorsRelaxation oscillatorsLC oscillatorsHintPhase-shift oscillators utilized where the extensive frequency ranges 97). Radio receivers use ___________ oscillators.RC phase shiftClappCrystalHartleyHintHartley oscillators are used for operating at radio frequencies 98). Phase-Locked loop (PLL) uses ________ oscillators.RC phase-shift oscillatorsMultivibratorsRelaxation oscillatorsVoltage-Controlled oscillatorsHint The output signal in PLL 99). Digital systems prefer _____________ oscillators.RC phase shiftClappCrystalHartleyHintThe precise and highest stability in frequency obtained by using Crystal oscillators 100). The signal generators utilized in the general laboratories are _______ oscillators.RC phase shift oscillatorWien bridge oscillatorCrystal oscillatorsHartley oscillatorHintWithout input, Wien bridge oscillators produce continuous oscillations of output 101). 555 Timer consists of ________.Two comparatorsFlip-flopDischarge transistorAll the aboveHint555 Timer consists of two comparators, a flip-flop, a discharge transistor 102). The crystal in crystal oscillator acts as __________.FilterPower sourceResonant circuitBoth b & cHintResonant circuitRead More About Colpitts Oscillator Time is Up!