Chapter 21 Self Test: Oscillators - Electronics Principles by Malvino/Bates

An oscillator always needs an amplifier with a. Positive feedback b. Negative feedback c. Both types of feedback d. An LC tank circuit

a

The voltage that starts an oscillator is caused by a. Ripple from the power supply b. Noise voltage in resistors c. The input signal from a generator d. Positive feedback

b

The Wien-bridge oscillator is useful a. At low frequencies b. At high frequencies c. With LC tank circuits d. At small input signals

a

A lag circuit has a phase angle that is a. Between 0° and 190° b. Greater than 90° c. Between 0° and 290° d. The same as the input voltage

c

A coupling circuit is a a. Lag circuit b. Lead circuit c. Lead-lag circuit d. Resonant circuit

b

A lead circuit has a phase angle that is a. Between 0° and 190° b. Greater than 90° c. Between 0° and 290° d. The same as the input voltage

a

A Wien-bridge oscillator uses a. Positive feedback b. Negative feedback c. Both types of feedback d. An LC tank circuit

c

Initially, the loop gain of a Wien bridge is a. 0 b. 1 c. Low d. High

d

A Wien bridge is sometimes called a a. Notch filter b. Twin-T oscillator c. Phase shifter d. Wheatstone bridge

a

To vary the frequency of a Wien bridge, you can vary a. One resistor b. Two resistors c. Three resistors d. One capacitor

b

The phase-shift oscillator usually has a. Two lead or lag circuits b. Three lead or lag circuits c. A lead-lag circuit d. A twin-T filter

b

For oscillations to start in a circuit, the loop gain must be greater than 1 when the phase shift around the loop is a. 90° b. 180° c. 270° d. 360°

d

The most widely used LC oscillator is the a. Armstrong b. Clapp c. Colpitts d. Hartley

c

Heavy feedback in an LC oscillator a. Prevents the circuit from starting b. Causes saturation and cutoff c. Produces maximum output voltage d. Means that B is small

b

When Q decreases in a Colpitts oscillator, the frequency of oscillation a. Decreases b. Remains the same c. Increases d. Becomes erratic

a

Link coupling refers to a. Capacitive coupling b. Transformer coupling c. Resistive coupling d. Power coupling

b

The Hartley oscillator uses a. Negative feedback b. Two inductors c. A tungsten lamp d. A tickler coil

b

To vary the frequency of an LC oscillator, you can vary a. One resistor b. Two resistors c. Three resistors d. One capacitor

d

Of the following oscillators, the one with the most stable frequency is the a. Armstrong b. Clapp c. Colpitts d. Hartley

b

The material that has the piezoelectric effect is a. Quartz b. Rochelle salts c. Tourmaline d. All the above

d

Crystals have a very a. Low Q b. High Q c. Small inductance d. Large resistance

b

The series and parallel resonant frequencies of a crystal are a. Very close together b. Very far apart c. Equal d. Low frequencies

a

The kind of oscillator found in an electronic wristwatch is the a. Armstrong b. Clapp c. Colpitts d. Quartz crystal

d

A monostable 555 timer has the following number of stable states: a. 0 b. 1 c. 2 d. 3

b

An astable 555 timer has the following number of stable states: a. 0 b. 1 c. 2 d. 3

a

The pulse width from a one-shot multivibrator increases when the a. Supply voltage increases b. Timing resistor decreases c. UTP decreases d. Timing capacitance increases

d

The output waveform of a 555 timer is a. Sinusoidal b. Triangular c. Rectangular d. Elliptical

c

The quantity that remains constant in a pulse-width modulator is a. Pulse width b. Period c. Duty cycle d. Space

b

The quantity that remains constant in a pulse-position modulator is a. Pulse width b. Period c. Duty cycle d. Space

d

When a PLL is locked on the input frequency, the VCO frequency a. Is less than f0 b. Is greater than f0 c. Equals f0 d. Equals fin

d

The bandwidth of the low-pass filter in a PLL determines the a. Capture range b. Lock range c. Free-running frequency d. Phase difference

a

The output frequency of the XR-2206 can be varied with a. An external resistor b. An external capacitor c. An external voltage d. Any of the above

d

FSK is a method of controlling the output a. Functions b. Amplitude c. Frequency d. Phase

c