Figure 4-31.--Wiring diagram for an early model 12-inch mercury-xenon arc searchlight.
Operating Circuit.-- The operating circuit
Starting Circuit.-- The secondary of the step-up
includes four ballast resistors, which permit the lamp to
transformer in the starting circuit supplies high voltage
operate at 25 volts during warmup after the arc has been
to a radio-frequency circuit consisting of a spark gap,
capacitors, and the three-turn primary of the pulse
struck and up to 65 volts at full lamp output. A fifth
resistor is automatically connected during starting and
transformer. The secondary of the pulse transformer
removed after the arc is struck
produces a momentary high voltage for starting the
arc.
Safety Switch .--The safety switch has three
When the arc starts, the secondary of the pulse
contacts, S-3, S-4, and S-6. The actuating lever of this
switch projects a short distance into the searchlight drum
transformer is short-circuited and the lamp is now
from the top of the starter assembly. It is mechanically
energized on line voltage reduced by the drop in the
linked to the reflector or the shutter housing, depending
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