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87 Cards in this Set
- Front
- Back
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What generates outputs as sinusoidal, square, rectangular, sawtooth, and trapezoidal waveshapes?
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wave generators
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What type of wave generator can provide its own input signal?
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oscillators
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What are two types of oscillators?
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sinusoidal and nonsinusoidal
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What make the frequency-determining network of RC oscillators?
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resistors and capacitors
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What make the frequency-determining network of LC oscillators?
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inductors and capacitors
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What type of oscillators uses low-frequency generators?
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RC oscillators
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What type of oscillators is used for the higher radio frequencies?
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LC oscillators
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What type of oscillators provides excellent frequency stability?
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Crystal-Controlled oscillators
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What type of oscillators produce trapezoidal waveform?
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nonsinusoidal oscillators
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Multivibrators and blocking oscillators are what type of oscillators?
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nonsinusoidal oscillators
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What type of oscillators have outputs characterized by a sudden change or relaxation and referred to as relaxation oscillators?
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nonsinusoidal oscillators
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Oscillators can be thought of as what that provides itself with an input signal through feedback?
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amplifier
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Regenerative feedback is considered what kind feedback?
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positive
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What device in oscillators acts as a filter, allowing only the desired frequency to pass?
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frequency-determining device (fdd), or frequency-determining network (fdn)
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What is needed in oscillators to provide the necessary gain for the signal?
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amplification
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What is needed in oscillators to sustain oscillations?
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regenerative feedback
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What is needed in oscillators to maintain the desired output frequency?
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frequency-determining device
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What is the primary purpose of an oscillator?
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to generate a given waveform at a constant peak amplitude and specific frequency
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What may cause the loss of stability in oscillators?
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high output power
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How can oscillator keep stability and produce high power output at a same time?
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have oscillators followed by a higher-power buffer amplifier
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What provides isolation between the oscillator and the load to prevent changes in the load from affecting the oscillator?
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buffer amplifier
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What class of oscillators is used when efficiency is important?
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class C
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What class of oscillators is used when distortion must be kept at a minimum?
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class A
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What is the reduction of amplitude in an oscillator circuit referred to?
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damping
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What can overcome damping effect in an oscillator?
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regenerative feedback
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What is the maintenance of oscillations in a tank circuit in the intervals between pulses of excitation energy?
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flywheel effect
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What is the property of a crystal by which mechanical forces produce electrical charges and, conversely, electrical charges produce mechanical forces?
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piezoelectric effect
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What is the frequency produced by a crystal?
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natural resonant frequency
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What type oscillator uses tickler coil for feedback?
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Armstrong oscillator
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What type oscillator uses tapped coiled for feedback?
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Hartley oscillator
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What type oscillator uses split coil for feedback?
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Hartley oscillator
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What type oscillator uses split capacitors for feedback?
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Colpitts oscillator
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What type methods of feedback take some of the energy from the inductor?
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tickler coil, tapped coil, split coil
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What are the two methods used for feedback coupling?
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inductive, capacitive
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what are the three basic configurations of transistor oscillators?
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common-base, common-emitter, common-collector
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What type configuration of feedback must provide a phase shift of approximately 180 degrees?
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common-emitter
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What type configuration of feedback has gain less than unity and seldom used in oscillator?
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common-collector
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What type configuration of feedback make impedance matching slightly harder and better high-frequency response?
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common-base
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To determine either series-fed or shunt-fed oscillators, dc power supplied to the transistor has to be directly or separated to what?
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tank circuit
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What is a prime requirement for good frequency stability in oscillators?
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a constant supply voltage
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What can achieve a relatively constant ratio of two voltages?
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the use of common collector and common emitter
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What makes the output voltage directly proportional to the supply voltage?
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feedback
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What ensures good amplitude stability because of feedback?
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regulation of the supply voltage
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What are three characteristics of Armstrong oscillator?
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LC tuned circuit
tickler coil as feedback a class C amplifier |
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The Hartley oscillator is an improvement over the Armstrong oscillator. (True/False)
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True
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The Hartley oscillator can operate class C and class A. (True/False)
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True
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What is the main difference between the Armstrong and the Hartley oscillators?
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the feedback coil is a split inductor not a separate coil
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Both the Armstrong and the Hartley oscillators have a tendency to be unstable in frequency because of junction capacitance. (True/False)
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True
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What is the main difference between shunt-fed Hartley oscillator and the Colpitts oscillator?
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two capacitors are used in the tank circuit instead of a tapped coil in the Colpitts
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Colpitts, Armstrong, and Hartley oscillators, which has a better frequency stability?
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Colpitts
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What kind of oscillator uses resistors and capacitor to provide regenerative feedback?
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Resistive-Capacitive feedback oscillator
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What kind feedback device does not have tank circuit and the oscillating ability?
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RC frequency-determining device
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What kind of oscillator must use class A biasing?
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RC feedback oscillator
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To provide 180 degree phase shift, how many RC network is required?
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3
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What must be used with the three-section RC network in phase-shift oscillators?
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a high-gain transistor
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More then three RC sections actually reduces the overall signal within the network. (True/False)
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True
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What kind of oscillator is used to produce an output which is highly stable and at a very precise frequency?
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crystal-controlled oscillator
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What determines the resonant frequency in a crystal oscillator?
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the thickness of the crystal
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The thinner the crystal, the higher the resonant frequency. (True/False)
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True
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What is the standard means used for maintaining the frequency of radio transmitting stations?
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crystal-controlled oscillator
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Under what condition crystals produce more than one frequency?
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when thickness is not uniform
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What is the name for less pronounced frequencies produced by crystals?
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spurious frequencies
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Depending upon the circuit characteristics, the crystal can act as a capacitor, an inductor, a series-tuned circuit, or a parallel-tuned circuit. (True/False)
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True
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Crystal acts as a capacitor under what condition (frequency response)?
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impedance increases as teh frequency is lowered
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Crystal acts as an inductor under what condition (frequency response)?
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impedance increases when frequency is raised
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When crystal tuned circuit act as what, it has a maximum impedance?
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parallel-tuned circuit
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When crystal tuned circuit act as what, it has a minimum impedance?
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series-tuned circuit
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The frequency stability of crystal-controlled oscillators depends on what?
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Q of the crystal
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What determines Q of the crystal?
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cut, type of holder, accuracy of grinding
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What oscillator is a modified Colpitts oscillator?
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Pierce oscillator
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What a crystal of Pierce oscillator (common-base) equals to in Colpitts oscillator?
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parallel-resonant circuit
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What changes the frequency of Pierce oscillator (common-base)?
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C1, CE and crystal
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What kind of oscillator produce output pulses at a predetermined frequency for an indefinite period of time and operates continuously?
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sinusoidal (sine-wave) oscillator
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What is a sine-wave oscillators that are turned on and off at specific times?
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pulsed oscillators or ringing oscillators
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What is defined as a sinusoidal wave having a frequency that is a multiple of the fundamental frequency?
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harmonics
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A sine wave that is twice that fundamental frequency is referred to as what?
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second harmonic
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What is a useful purpose of harmonics?
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frequency multiplication
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Relatively good stability can be achieved at what frequencies?
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lower
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What are special class C amplifiers that are biased at 3 to 10 times the normal cutoff bias?
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frequency multipliers
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Second harmonic generator is also known as what?
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frequency doubler
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What is normally as high in multiplication as is practical?
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fourth harmonic generator (frequency quardruplet)
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What will the tank circuit become when the output tank circuit is tuned to the required harmonic?
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acts as a filter, accepting the desired frequency and rejecting all others
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What decreases the loading effect on the oscillator by reducing the interaction (matching impedance) between the load and the oscillator?
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buffer amplifier
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A buffer amplifier is also what?
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common-collector amplifier
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What has a high input impedance and a low output impedance?
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common-collector amplifier
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What is the oscillator signal coupled forward, but load changes not coupled back to the oscillator?
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one-way coupling
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What can achieve one-way coupling?
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high input impedance and low output impedance
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