Questions and Problems

Author: N.H. Crowhurst

1. Shielding prevents what three kinds of induction? In what ways can this induction occur?

2. What effect does circuit impedance have on the relative importance of the different ways induction occurs? Explain.

3. What are the essential features and characteristics of (a) magnetic, (b) electromagnetic, and (c) electric shielding?

4. Explain the advantages and limitations of coaxial lines.

5. Give the deficiencies associated with using lines at high and low impedance that lead to choice of a medium line impedance. What are common values of line impedance?

6. How can a condition near to instability (oscillation) cause distortion due to transient effects? Explain this possibility with reference to both low- and high-frequency near-instability.

7. Describe a group of transient effects in amplifier performance that is essentially caused by power supply features.

8. Name four major types of oscillator designed to produce sine waves. Explain the principle of operation of each. Which give the best waveform? Show why.

9. What other types of waveform are required from oscillators, and for what purposes?

10. A tube used in an oscillator circuit amplifies with the production of 5% harmonic. What positive and negative loop gain figures must be used so the output from this oscillator is 0.1%?

11. What is the essential difference between the phase-shift and positive feedback types of oscillator?

12. What difference is there, from a musical viewpoint, between a square wave and a sawtooth?