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34. Using a 50-mA, 1000-� d’Arsonval movement, design
a multirange milliammeter having scales of 25 mA, 50
mA, and 100 mA. Show the circuit and component
values.
35. A d’Arsonval movement is rated 50 mA, 1000 �.
a. Design a 15-V dc voltmeter. Show the circuit and
component values.
b. What is the ohm/volt rating of the voltmeter?
36. Using a 1-mA, 100-� d’Arsonval movement, design a
multirange voltmeter having scales of 5 V, 50 V, and 500
V. Show the circuit and component values.
37. A digital meter has an internal resistance of 10 M� on its
0.5-V range. If you had to build a voltmeter with a d’Arsonval
movement, what current sensitivity would you
need if the meter were to have the same internal resistance
on the same voltage scale?
*38. a. Design a series ohmmeter using a 100-mA, 1000-�
movement; a zero-adjust with a maximum value of
2 k�; a battery of 3 V; and a series resistor whose
value is to be determined.
b. Find the resistance required for full-scale, 3/4-scale,
1/2-scale, and 1/4-scale deflection.
c. Using the results of part (b), draw the scale to be used
with the ohmmeter.
39. Describe the basic construction and operation of the
megohmmeter.
*40. Determine the reading of the ohmmeter for the configuration
of Fig. 7.96.
SECTION 7.9 Computer Analysis
�
(a)
12 �
R 1
12 �
R 3
R 2
12 �
PSpice or Electronics Workbench
41. Using schematics, determine V1, V3, Vab, and Is for the
network of Fig. 7.16.
42. Using schematics, determine Is, I5, and V7 for the network
of Fig. 7.22.
FIG. 7.96
Problem 40.
18 �
R 1
18 �
R 2
�
(b)
18 �
R 3
PROBLEMS ⏐⏐⏐ 253