[Illustration: Fig. 49.--Multiple battery switch.]
Multiple Battery Switch.--To control the speed of the train and economize
current a multiple battery switch is useful. Fig. 49 explains how to make
and connect up such a switch. The contacts, C1 to C5, lie in the path of
the switch lever, and are connected through binding posts T1 to T6 with one
terminal of their respective cells. The cells are coupled up in series to
one another, and one terminal of the series with binding posts T0 and T6.
By moving the lever, any number of the cells can be put in circuit with T7.
The button under the head of the lever should not be wide enough to bridge
the space between any two contacts. Change the order of the cells
occasionally to equalize the exhaustion.
[Illustration: FIG. 50.--Adjustable resistance for controlling current.]
Resistance.--With accumulators, a "resistance" should be included in the
circuit to regulate the flow of current. The resistance shown in Fig. 50
consists of a spiral of fine German silver wire lying in the grooved
circumference of a wood disc. One of the binding posts is in connection
with the regulating lever pivot, the other with one end of the coil.
Pages:
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108