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• 1. Oscillator Basics
• 2. RF Sine Wave Oscillators
• 3. AF Sine Wave Oscillators
• 4. CR Relaxation Oscillators

Module 3.5

AF Oscillators Quiz

Try this quiz, based on the information you can find in Oscillators Module 3. Submit your answers and see how many you get right. If you get any answers wrong. Just follow the hints to find the right answer and learn about Oscillators as you go.

1.

Refer to Fig. 3.5.1. How much is the feedback signal phase shifted by C3,R4,?

• a) 90°
• b) 60°
• c) 45°
• d) 30°

2.

Refer to Fig. 3.5.1. What is the approximate frequency of oscillation?

• a) 440Hz
• b) 550Hz
• c) 650Hz
• d) 2.7kHz

3.

An advantage of Wien Bridge oscillators compared to Phase Shift types is that::

• a) Wien bridge oscillators can be used over a much wider frequency range than Phase Shift types.
• b) It is easier to make variable frequency oscillators with Wien Bridge types than Phase shift types.
• c) Wien bridge oscillators can use op-amps.
• d) Wien bridge oscillators always have a lower output impedance than Phase Shift types.

4.

If each low pass filter in Fig. 3.5.2 has a voltage gain of 0.5, how much gain will be required from the amplifier for oscillations to start?

• a) 1
• b) 1.3
• c) 8.3
• d) 29

5.

Refer to Figs. 3.5.2.and 3.5.1 Which of the following comparisons is true?

• a) Frequency calculation is more complex in Fig. 3.5.2 than in Fig. 3.5.1.
• b) The filters used in Fig. 3.5.2 cause less distortion than in Fig. 3.5.1.
• c) Loading on the phase shift networks in Fig. 3.5.2 is reduced, compared to Fig. 3.5.1
• d) The output impedance of Fig. 3.5.2 is higher than that of Fig. 3.5.1

6.

Which formula in Fig 3.5.3 should be used for finding the frequency of oscillation of a buffered phase shift oscillator?

• a)
• b)
• c)
• d)

7.

If the circuit in Fig. 3.5.4 is supplied with an AC signal and the ammeter reads zero amperes, what is the phase relationship between points X and Y?

• a) 180°
• b) 90°
• c) 45°
• d) 0°

8.

What is the purpose of the lamp in Fig. 3.5.5?

• a) To stabilise the frequency of oscillation.
• b) To indicate the oscillations are present.
• c) To prevent distortion
• d) To give over current indication.

9.

Refer to Fig 3.5.6. What is the purpose of TR1?

• a) To provide automatic gain control (AGC) for IC1
• b) To provide automatic frequency (AFC) control for IC1
• c) To provide a high impedance input for the feedback system.
• d) To provide a constant current DC supply for IC1.

10.

Refer to Fig 3.5.6. What is the approximate low frequency limit of the Oscillator?

• a) 70Hz
• b) 150Hz
• c) 1.5kHz
• d) 7kHz

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