Electronics Oscillator Circuit Quiz

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Questions and Answers

What is the primary goal of feedback in an oscillator circuit?

To sustain oscillation (correct)

To produce a distorted waveform

To keep the gain at a minimum

To maximize the gain

What is a common reason for an oscillator to fail to start?

Low stage gain (correct)

High power supply voltage

High output impedance

In-phase feedback

What is an advantage of a crystal-controlled oscillator over a VFO?

High output power

Single-frequency operation (correct)

Low power consumption

Ease of frequency adjustment

What is a disadvantage of using discrete components instead of ICs?

Lower component density Signup and view all the answers

Which component is typically not practical for fabrication in an IC?

Inductors Signup and view all the answers

What is the purpose of negative feedback in an op amp?

To control the gain Signup and view all the answers

What is the purpose of comparing the output voltages to the internal voltage divider in a 555 timer?

To trigger the output signal Signup and view all the answers

What is the duty cycle of a signal defined as?

The time the output is active divided by the total period of the output signal Signup and view all the answers

What is the resolution of a digital-to-analog converter (DAC)?

The smallest analog output change that can occur as a result of an increment in the digital input Signup and view all the answers

What is the phenomenon exhibited by a crystal when a mechanical force across the crystal causes a small voltage to be generated?

Piezoelectric effect Signup and view all the answers

What is the formula for determining the time period of a monostable 555 multivibrator?

T = 0.33RC Signup and view all the answers

Which pin of the 555 timer is used to reset the timer?

Pin 4 Signup and view all the answers

What type of oscillator is characterized by a split capacitor in its tank circuit?

Colpitts oscillator Signup and view all the answers

Which type of circuit is required for oscillation?

A stage with gain Signup and view all the answers

What is a common classification of filters?

All of the above Signup and view all the answers

What is the purpose of a capacitor in the feedback path of an op-amp circuit?

To act as an integrator Signup and view all the answers

Which oscillator is known for its good frequency stability?

Crystal oscillator Signup and view all the answers

What type of circuit is a phase-selective circuit?

Frequency-selective circuit Signup and view all the answers

Study Notes

Oscillator Circuits

Feedback in an oscillator circuit should be just enough to sustain oscillation.
Low power supply voltage, low stage gain, and in-phase feedback can prevent an oscillator from starting.
Crystal-controlled oscillators have the advantage of single-frequency operation and low drift.

Integrated Circuits (ICs)

ICs have higher component density, ease of maintenance, and lower current consumption compared to discrete components.
Inductors are generally not practical for fabrication in an IC.

Operational Amplifiers (Op Amps)

Op amps usually employ negative feedback to control the gain.
Op amps compare the input voltages to the internal voltage divider.

555 Timer

The duty cycle of a 555 timer is defined as the time the output is active divided by the total period of the output signal.
Pin 1 of the 555 timer is the ground pin.
Pin 2 is the trigger pin.
The standard 555 package includes 2 comparators.
Reset is present at pin 4 of the 555 timer.

Digital-to-Analog Converters (DACs)

The resolution of a DAC is the smallest analog output change that can occur as a result of an increment in the digital input.

Crystal and Piezoelectric Effect

A crystal demonstrates the piezoelectric effect when a mechanical force across the crystal causes a small voltage to be generated.

Monostable 555 Multivibrator

The time period of a monostable 555 multivibrator is T = 1.1RC.

Filters

A band-reject filter has two stop bands.
The gain of the first-order low-pass filter decreases at the rate of 20dB/decade.
An electrical filter is a frequency-selective circuit.
Filters can be classified as analog or digital, passive or active, and audio or radio frequency.

Oscillators

The Colpitts oscillator is characterized by a split capacitor in its tank circuit.
A crystal oscillator is a fixed frequency oscillator.
The Colpitts oscillator gives good frequency stability.
Oscillation requires a stage with gain and negative feedback.
A Colpitts oscillator can be recognized by a split capacitance in the tuned circuit.