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 arcs Feedback Frequency Linearity Hint Electric arcs were utilized for lighting2). Oscillator circuit built by _______________. Humphry Davy Benjamin Silliman Elihu Thomson Ernst Lecher HintOscillator circuit in the year 18923). Parametric oscillator circuit is developed by ________. Humphry Davy Benjamin Silliman Elihu Thomson George Francis FitzGerald HintGeorge Francis FitzGerald realized if the resistance in the resonance circuit is either made to zero or else negative4). Arc oscillator rediscovered by _____________. Humphry Davy Benjamin Silliman William Duddell Elihu Thomson HintWilliam Duddell made popular the rediscovered Arc oscillator5). Vacuum-tube Feedback Oscillators were invented in ___________. 1912 1913 1914 1915 HintAudion an electronic amplifying or detecting vacuum tube6). Edwin Armstrong preferred ______________feedback. Positive Negative Both a & b None of the above HintRegenerative receivers7). _______________ converts Direct Current (DC) signals available from the power supply units to Alternate Current (AC) signals. Micro-controllers Oscillators Transformer Relays HintOscillator accepts DC voltages and generates periodic waveform8). A _________ criterion determines mathematical condition to obtain sustained oscillations. Pythagorous Abel-Jacobi Barkhausen None of the above HintBarkhausen criterion determines9). What are the types of oscillators based on frequency as the parameter? Low frequency oscillators Audio oscillators Radiofrequency oscillators All the above HintLFO and HFO10). The _____________ feedback is used in oscillators. Positive Negative Neither negative nor positive None of the above HintPositive feedback gives the highest gain11). 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 HintCrystal oscillators operate at high frequencies12). Both negative and the positive feedback is present in _______ oscillator. RC phase shift oscillator Wien bridge oscillator Twin T oscillators Crystal oscillator HintTwo transistors are present in Wien bridge oscillators13). The filter in the RC oscillator circuit consists of ___________. Inductors Resistors Capacitors Both b & c HintLow-frequency oscillators14). Which of these oscillators doesn’t consists of LC tank circuit? Colpitts oscillator Hartley oscillator Clapps oscillator Wien bridge oscillator HintWien bridge oscillator consists of resistors and capacitors15). Positive feedback results in ___________ oscillations. Damped Undamped Modulated None of the above HintOscillations with constant amplitude and time16) .Microprocessors uses _________ oscillators. RC phase shift oscillator Wien bridge oscillator Twin T oscillators Crystal oscillator HintProcessing of high-speed data17). UJT is a ____________ oscillator. Wien bridge Feedback Relaxation None of the above HintUJT produces non-sinusoidal waveform18). The very first and the mostly used circuit of Relaxation oscillator is __________. Astable Multivibrator Bistable Multivibrator Monostable Multivibrator Multiplexer HintAstable multivibrator was discovered by French Engineers19). __________ Circuits are the base for the design of contemporary microwave oscillators. Positive-resistance Zero resistance Negative- resistance Both a & b HintK. Kurokawa is the person to determine20). Multivibrators comes under the category of ___________ oscillators. Sinusoidal Square wave Ramp Triangular wave HintMultivibrators produces square wave as the output21). Non-sinusoidal oscillators are _____________. Multivibrators Square wave oscillators Hartley oscillators Both a & b HintRelaxation oscillator22). 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 HintHigher frequencies23). Which is the most stable oscillator? RC phase shift oscillator Wien bridge oscillator Twin T oscillators Crystal oscillator HintStable frequencies can be generated using Crystal oscillators24). 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 HintCapacitor and the energy at the inductor are inversely proportional25). Hartley oscillator consists of ________ inductors. One Two Three Four HintTwo inductors are connected in series and parallelOscillator MCQs for Interview26). The phase shift obtained at the feedbacks loop is ____________ degrees. 0 180 270 90 HintSustained oscillations27). Theoretically the gain in the oscillator must be equal to _______. High Low Unity None of the above HintGain must be slightly greater than 128). Which oscillator used to generate 1 Mega hertz signal? RC phase shift oscillator Wien bridge oscillator Twin T oscillators Hartley oscillator HintLC circuit29). Which oscillators are preferred in the Timing elements? RC phase shift oscillator Wien bridge oscillator Crystal oscillators Hartley oscillator HintOscillators have the highest stability of frequency30). Hartley oscillator has ________ capacitors in its Tank circuit. One Two Three Four HintOne capacitor and two inductors31). 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 HintRealized by using Op-amps, FET, or BJT.32). How many capacitors are present in Colpitts oscillator? One Two Three Four HintTwo capacitors are in series33). Additional capacitor in series with the inductor is placed in which oscillator? RC phase shift oscillator Clapp oscillator Crystal oscillators Hartley oscillator HintFrequency stability34). The flow of energy is unidirectional in which oscillators? Harmonic oscillators Relaxation oscillators Both a and b None of the above HintHarmonic oscillators possess a unidirectional flow of energy35). 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 HintRelaxation oscillators are capable of exchanging the flow of energy36). The oscillations frequency in harmonic oscillator can be determined by ______________. Feedback path Charging of time constants Discharging of time constants Both b and d HintHarmonic oscillators are also known as Feedback oscillators37). Oscillations frequency of relaxation oscillators can be determined by ___________. Feedback path Charging of time constants Discharging of time constants Both b and d HintOscillation frequency depends upon the charging and discharging38). Harmonic oscillators generate _______ waveforms as output. Saw tooth Square Triangular Sinusoidal HintLow-distorted sinusoidal waveforms39). Relaxation oscillators generate _______ waveforms as output. Saw tooth Square Triangular All the above HintNon-sinusoidal signals40). The device active in the LC oscillator of transistor is _________. Tank circuit Bias circuit Transistor All the above HintTransistor in the oscillator41). The drawback of LC oscillators are _____________. Instability of frequency Poor waveforms Cannot be preferred for low frequencies All the above HintRC oscillators42). Inductors used in LC oscillators makes the circuit bulky and ____________. Expensive Cheap Moderate None of the above HintExpensive due to inductors43). RC oscillators are also known as __________________ Phase shift oscillators Clapp oscillator Crystal oscillators Hartley oscillator HintOutput sine signal generated is based on the phase shift44). Total phase shift in the RC oscillators is _______. 0 180 270 90 HintEach section of RC produces 60 degrees45). The frequency in the Phase shift oscillators can be determined by __________ components. Inductors Capacitors Resistors Both b and c HintResistors and capacitors present to determine the frequency46). Which oscillators has fixed set of frequencies? RC phase shift oscillator Clapp oscillator Crystal oscillators Hartley oscillator HintHybrid clock47). What is the reason of failure of Crystal oscillators? Instability of frequency Poor waveforms Cannot be preferred for low frequencies Overheating HintCrystal oscillators consist of materials made of Piezo48). The Q factor of the Crystal oscillator is ____________. High Low Moderate None of the above HintUnder damped49). The network of RC in the Wien bridge oscillators is known as ___________. Lead network Lag network Lead-Lag network None of the above HintPhase-shift present in the network50). The increase in the frequency makes the phase-shift ____________ in the Wien bridge oscillator. Lead Lag Lead-Lag None of the above HintIncreased frequencyOscillator Multiple Choice Question and Answers51). The decrease in the frequency makes the phase-shift ___________ in the Wien bridge oscillator. Lead Lag Lead-Lag None of the above HintPhase shift tends to lead52). How many RC networks present in Twin-T oscillators? One Two Three Four HintTwo RC networks53). Feedback in the colpitts oscillator is by __________ component. Resistor Inductor Capacitor Transformer HintVoltage divider in the LC circuit54). Tank circuits in Colpitts oscillator possess ________ capacitors. One Two Three Four HintTwo capacitors present in the LC circuit55). Improved performance of Colpitts oscillator in comparison to the Hartley oscillator is because of _________ components. Resistor Inductor Capacitor Transformer HintCapacitive elements in the Colpitts oscillator56). Gain device of Colpitts oscillators behaves as _______ filter. Low pass High pass Band pass Band reject HintOscillation frequencies are limited to certain ranges57). Which feedback is present in Colpitts oscillator? Positive Negative Both positive and negative None of the above Hint To satisfy the Barkhausen condition58). What is the active element of the Colpitts oscillator? Diode Transformer Transistor All the above HintAmplify the weak signals transistor is used59). The circuit of Colpitts oscillator is capacitive and improves the __________. Impedance Stability of frequency Both a and b None of the above HintFrequency stability60). Oscillations classified as sustained and damped based on ___________. Power Noise Frequency Amplitude HintVariations in amplitude61). Colpitts oscillator’s frequency is ________. 1/2π√LCt 1/3π√LCt 1/4π√LCt 1/5π√LCt HintCt determines the equivalence capacitance62). For the feedback component used in Hartley oscillators are _____________. Resistors Inductors Capacitors Transformer HintInductors in the Hartley oscillators63). Number of capacitors in Hartley oscillator is _______. One Two Three Four HintHartley oscillator consists of one capacitor64). Number of inductors in Hartley oscillators are _________. One Two Three Four HintTwo inductors are present in the Hartley oscillator's65). Difference between Hartley and the Colpitts oscillators is _________. Frequency Power supply Feedback across different components Both a and b HintFeedback66). Self-limiting oscillators are ___________. RC phase-shift oscillators Multivibrators Relaxation oscillators LC oscillators HintTank circuit67). The voltage divided in the Clapps oscillator is due to _________. Resistors Inductors Capacitors Transformer HintModified version of the Colpitts oscillators68). Which effect is present in Crystal oscillators? Triboelectric effect Piezoelectric effect Both a and b None of the above HintPiezo69). Threshold voltage is pre-determined in ______________. RC phase-shift oscillators Multivibrators Relaxation oscillators LC oscillators HintCapacitors present in Relaxation oscillators70). Relaxation oscillator made up of op-amp circuit is referred to as ____________. Astable Multivibrator Monostable Multivibrator Bistable Multivibrator None of the above HintAstable multivibrator possesses two states71). Relaxation oscillator’s op-amp circuit generates ________ signal. Sawtooth Square wave Ramp Triangular HintSignal undergoes a transition between two states72). Possibility of signaling of internal clock in the digital circuits is by ____________. RC phase-shift oscillators Multivibrators Relaxation oscillators LC oscillators HintFor internal signaling of clocks in the circuits relaxation oscillators are used73). VCO stands for ________________. Voltage-controlled oscillator Value controlled oscillations Voltage counter operations None of the above HintThe 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 __________. Power Current Input voltage All the above HintInput voltage controls the frequency of oscillations75). Phase-shift at the tank circuit of Hartley oscillators is ____________ degrees. 0 90 180 270 HintMeet the Barkhausen criteriaOscillators Important Questions with Answers76). An LC circuit in the oscillator is known as ____________. Resonant circuit Tank circuit Tuned circuit All the above HintInductor represented as L and the capacitor represented as C77). RFC stands for ______________. Radio Frequency Choke Radar Frequency Communication Radio Frequency Communication None of the above HintRadiofrequency choke at the collector provides higher reactance78). Clapp Oscillator preferred above __________ for the construction of Variable frequency oscillators. RC phase shift oscillator Colpitts oscillator Crystal oscillators Hartley oscillator HintTuning circuits present at receivers79). How many capacitors are present in the Clapp oscillators? One Two Three Four HintVoltage divider circuit in the Clapp oscillator80). Which type of feedback is present in Clapp oscillators? Positive Negative Both Positive and Negative None of the above Hint Positive feedback is preferred81). 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 HintVoltage divider circuit formed with three capacitors82). _____________ oscillator has the constant frequency in the output. RC phase shift oscillator Clapp oscillator Crystal oscillators Hartley oscillator HintCrystal oscillator's main feature is the constant frequency83). If there is no signal at input applied what triggers the operation of oscillators? Temperature Pressure DC Noise voltage HintPresence of noise voltage84). Harmonic oscillators are ________. Sinusoidal oscillators Non-sinusoidal oscillators Both a and b Relaxation oscillators HintGenerates sinusoidal waves85).Which of these is not considered as non-sinusoidal oscillators? Multivibrators Blocking oscillators Crystal oscillators None of the above HintSinusoidal oscillators86). If the value of capacitor is tends to be maximum the energy at the inductor reaches ___________ in LC oscillators. Minimum Maximum Undetermined Data insufficient HintCapacitor value and the inductor energy are inversely proportional87). If the frequency of the crystal tends to change with temperature, the crystal is said to have __________ coefficient of temperature. Zero Positive Negative Undetermined HintElectrical resistance increases with the increase in temperature88). Basic difference between oscillators and amplifiers is ___________. High gain Frequency stability No input signal needed No Dc supply HintWithout the application of input89). What is the limitation of Crystal oscillator? Low output High Q High output Cannot say HintLow output is the main limitation90). Ocxo is an acronym for ___________. Oven Controlled Crystal Oscillator Output Controlled Crystal oscillator Output Compensated Crystal Oscillator None of the above Hint The top-performing quartz Crystal oscillator91). Which oscillator is known as Meissner oscillator? RC phase shift oscillator Clapp oscillator Crystal oscillators Armstrong oscillator HintArmstrong oscillator is an electronic oscillator92). __________ oscillators have transformer coupling. RC phase shift oscillator Clapp oscillator Crystal oscillators Armstrong oscillator HintArmstrong oscillators are less popular93). Practically a circuit for triangular-wave is a combination of __________. Comparator and Inductor Comparator and Integrator Capacitor and Inductor Capacitor and Integrator HintTriangular wave generators use fast comparators94). __________ oscillators frequency gets varied by varying DC control voltage. RC phase shift oscillator Clapp oscillator Voltage Controlled oscillators Armstrong oscillator Hint Integrator used in VCO95). Crystal oscillators are mostly found in ___________. Radio receivers Radio transmitters Square generators None of the above HintRadio transmitters96). A GPS unit uses __________ oscillators. Phase-shift oscillators Multivibrators Relaxation oscillators LC oscillators HintPhase-shift oscillators utilized where the extensive frequency ranges97). Radio receivers use ___________ oscillators. RC phase shift Clapp Crystal Hartley HintHartley oscillators are used for operating at radio frequencies98). Phase-Locked loop (PLL) uses ________ oscillators. RC phase-shift oscillators Multivibrators Relaxation oscillators Voltage-Controlled oscillators Hint The output signal in PLL99). Digital systems prefer _____________ oscillators. RC phase shift Clapp Crystal Hartley HintThe precise and highest stability in frequency obtained by using Crystal oscillators100). The signal generators utilized in the general laboratories are _______ oscillators. RC phase shift oscillator Wien bridge oscillator Crystal oscillators Hartley oscillator HintWithout input, Wien bridge oscillators produce continuous oscillations of output101). 555 Timer consists of ________. Two comparators Flip-flop Discharge transistor All the above Hint555 Timer consists of two comparators, a flip-flop, a discharge transistor102). The crystal in crystal oscillator acts as __________. Filter Power source Resonant circuit Both b & c HintResonant circuitRead More About Colpitts Oscillator Time is Up! Time's up
