APPENDIX A--HOUSE WIRING SYMBOLS [How To Read Schematic Diagrams]

Answers to Questions

Section 1

1. A drawing, using symbols to represent the various parts, which shows the electrical connections of all components in a circuit. In addition, the value of components, color of leads, tube pin connections, voltage and resistance measurements, and many other items are usually included.

2. By a code letter and number.

3. It shows the various stages in the unit, and how they fit together.

4. The physical location of the components.

5. It shows each part as it actually looks in the chassis and is less expensive to produce.

6. They are the quickest, easiest, and most meaningful method of conveying the electrical connections within a circuit.

7. By an "exploded" view, which shows all the parts in their relative position, yet spreads them out so you can see each individual part.

8. The physical location of tubes and major components on top of the chassis. Certain items below the chassis may also be indicated by dashed lines.

9. Dial-cord strings, exploded views of record changers and tape recorders, motor-driven systems, and mechanical actions in organs or similar units.

10. The schematic.

Section 2

1. Ohm.

2. (A) To limit the flow of resistance through a circuit. (B) To provide a voltage drop.

3. An opposition to the flow of electrons through a circuit.

The electrical equivalent of friction.

4. Omega ().

5. A variable resistor.

6. R.

7. 27,000 ohms.

8. One whose resistance decreases when its temperature is increased.

9.

10.

Section 3

1. To store electrons.

2. No, they only appear to.

3. The farad.

4. The dielectric.

5. No.

6. Filter capacitors in power supplies.

7. One millionth.

8. The rotor.

9. C

10. (A) Polarized electrolytic capacitor. (B) Trimmer capacitor. (C) Nonpolarized electrolytic.

Section 4

1. Inductance.

2. Henry.

3. None, except for the slight amount of resistance it offers to the flow.

4. The magnetic lines of force set up by the primary cut the secondary winding.

5. Two or three solid lines

6. Choke.

7. The primary.

8. A powdered-iron core.

9. T and L

10.

Section 5

1. To control the flow of electrons.

2. To supply or emit electrons.

3. V

4. A gas tube.

5. The television picture tube.

6. The plate.

7. Through pins in the tube base.

8.

9. I

10. :

Section 6

1. Germanium, silicon, selenium.

2. It is not necessary.

3. NPN and PNP.

4. Base, collector, and emitter.

5. Q, X, V, T, TR

6.

7.

9 Base

10. Voltage Collector; Collector- Emitter regulation.

Section 7

1. To open and close a circuit.

2. Single-pole, single-throw.

3. Single-pole, double-throw.

4. To connect one point to either of two other points.

5. An electrically operated switch.

6. The two points are mechanically (but not electrically) connected.

7. To form an electromagnet.

8. S, SW, M, E o aeo

9.

Section 8

1. To convert an electrical signal into sound waves.

2. A fuse.

3. Incandescent and neon.

4. A cell is the basic unit; a battery is a group of cells.

5. Carbon, dynamic (or moving coil), capacitor, ceramic, and 10.

crystal.

9.

10. A circuit breaker.

Section 9

1. It simplifies the layout of the schematic by eliminating many lines.

2. Plug section.

3. Not always, but they can be.

4. A bus line.

5. The same as for any other leads.

6. Occupy less space; less expensive in initial cost; and less expensive to assemble on chassis.

7. A .shielded component.

8. That they are parts of a multiple unit.

9. +

+

Section 10

1. To convert AC to DC.

2. One to which power must be supplied.

3. No electrons will flow.

4. NPN and PNP.

5. The cathode follower.

6. From emitter to collector.

7. The cathode.

8. Common emitter, common base, and common collector.

9. Grounded cathode, grounded grid, and cathode follower.

10. The negative terminal.

Section 11

1. At the upper left-hand corner.

2. RF amplifier, oscillator, mixer.

3. Color of leads.

4. To automatically compensate for changes in signal strength.

5. In frequency only.

6. Break it down into individual stages.

7. Audio signal.

8. If one burns out, all tubes will go out.

9. Speaker.

10. To remove high-frequency signals present in the circuit.