Figure 9-17.--Schematic of an alarm switchboard.

Figure 9-17.--Schematic of an alarm switchboard.

the switchboard or in one of the lines. When a ground

common alarm section are an audible volume control,

is sensed, one of the lamps will illuminate.

a tone generator, a battery, a battery charger, the

common board, and the power supply.

VISUAL-AUDIBLE SWITCH.-- The visual-

GROUND DETECTION INDICATORS.--

audible switch is a two-position switch. When it

is placed in the VISUAL position, no audible alarm

The two ground detection indicators are provided to

will be received, only the alarm silence indicator will

indicate when a positive or negative ground exists in

9-16