26. Make diagram of a common-source current supply for many lines with
repeating coils and point out the travel of the voice currents.

27. Name the different parts which comprise a telephone set.

28. What is a magneto telephone?

29. Make diagram of the circuit of a series magneto set with receiver
on the hook and explain how the different currents are flowing.

30. Show diagram of the Stromberg-Carlson magneto desk telephone
circuit and describe its working.

31. Give sketch of the Stromberg-Carlson common-battery wall set
circuit.

32. Describe briefly the microtelephone set.

33. Make sketch of the Monarch common-battery wall set.

REVIEW QUESTIONS

ON THE SUBJECT OF TELEPHONY

PAGES 227--286

* * * * *

1. What is a party line?

2. What is usually understood by private lines?

3. What problem is there to overcome in connection with party lines?

4. State the two general classes of party-line systems.

5. Point out the defects of the series system.

6. Make sketch of a metallic bridging line and show the circuit for
the voice currents.

7. What is a signal code?

8. Give classification of selective party-line systems with short
definitions.

9. Describe the principle of selection by polarity and make sketch
illustrating this principle.

10. Make diagram of the circuit of a four-party station with relay.

11. Describe the process of tuning in the harmonic system.

12. What is the difference between the under-tune and in-tune systems?

13. Sketch circuit of Kellogg's harmonic system.

14. Illustrate the principle of a broken-line system by a sketch.

15. In what particulars does the party-line system in rural districts
differ from that within urban limits?

16. Describe and sketch Pool's lock-out system.

17. Make diagram of the K.B. lock-out system.

18. What is the object of the ratchet in this system?

19. Make diagram of simplified circuits of Roberts system.

20. Sketch and describe Roberts latching key and connections.

21. Sketch circuits of bridging station for non-selective party line.

22. How would you arrange the signal code for six stations on a
non-selective party line?

23. What is the limit of number of stations on a non-selective party
line under ordinary circumstances?

24. State the objections against the party polarity system as shown in
Fig. 172.

25. What are the advantages of the harmonic party-line system?