The main problem to be solved is, how to make the alarm mechanism of the
clock complete an electric circuit when the alarm "goes off."
If you examine an alarm clock of the type described, you will find that the
gong hammer lies against the gong when at rest, and that its shaft when in
motion vibrates to and fro about a quarter of an inch.
[Illustration: FIG. 89.--Plan of release gear of electric alarm, as
attached to clock.]
Fig. 39 shows a. method of utilizing the movement of the hammer. A piece of
wood, 2 inches long, wide enough to fill the space between the rear edge of
the clock and the hammer slot, and 1/2 inch thick, has its under side
hollowed out to the curvature of the clock barrel. This block serves as a
base for two binding posts or terminals, T1 T2. A vertical slit is made in
T1 and in this is soldered [to] one end of a little piece of spring brass
strip, 1 inch long and 1/4 inch wide. To the back of the other end of the
strip solder a piece of 1/20 inch wire, projecting l inch below the strip.
The strip must be bent so that it presses naturally against T2.
Pages:
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92