The Indianapolis times. [volume] (Indianapolis [Ind.]) 1922-1965, 1925-09-21

VI INC
Electric Light Association, is as fol-
lows:
Direct Current Arc Light Circuits
The direct current arc type street
lights are frequently the cause Of
disturbance to radio listeners.
The most likely causes Of inter
ference from arc lights are grounds,
loose connections and lamp jumping.
The first two rarely occur and are
easily found and fixed. Lamp jump
ing Is generally due to one Of the
following three causes, and can be
easily repaired: Broken or loose fit
ting globes, broken or loose flexible
connection strip from upper cleo
trode to upper electrode box, or bro
ken flexible connection cable to NOV
able clutch rod.
Street Lights Using Rectified Alter
mating Current
Mercury apor tubes for rectifying
alternating current for street light
ing systems sometimes cause radio
interference. The vacuum in these
tubes changes occasionally, and boil
ing in water restores the vacuum to
the proper point. When these tubes
are properly repaired, static disturb
ances are reduced to a minimum.
IncandeScent Street Lighting Sys-
TENS.
In some cases the disturbance from
incandescent street lighting sys-
TENS is audible several hundred feet,
caused by static leakage across the
porcelain base in the lamp itself.
Replacement Of the defective sock
cts with new ones eliminates the
trouble,
Elevator Controls
Elevator motors and controls are
the sources Of a disturbance fire.
quently difficult to remedy. Most
of the disturbance originates in the
contact in the elevator shaft, as
the operator of the car moves the
control handle back and forth.
Sparkling Of the motor and control
equipment also causes trouble.
TheimOstats
Thermostats are now used to con-
troll dozens of different forms Of
devices ranging from large indus
trial undertakings to the furnace
in the home. Thermostats some
times cause disturbances, depending
upon the size of the controls and
the amount Of current that they are
handling. Condensers and radio
frequency choke coils properly placed
will eliminate the disturbances.
Heating Pads
The make-and-break contact Their
mostat in some heating pads have
caused trouble, which can be RENE
died by proper attention to the de-
sign of the equipment.
7. Small Motors i'm the Home
The sparkling OF the commutator
In small motors is often a cause
Cleaning of these commutators and
installing of new brushes from time
to time, will reduce the disturbance.
8. Small Motors in Industry
Small motors using direct-current
are frequently sources of disturb
ance, covering limited areas, and
usually confined to the place in which
they are installed. Dirty and worn
commutators and sparkling brushes
cause most of the disturbance in this
type of motor. Connect condenser
across the motor leads, with the mid
point grounded.
Q. SLIPPING Alternating Current
Motors
The SLIPPING alternating current
motors are subject to heavy load.
and also when pitting and corrosion
of the slip ring occur, causing spark
ing, radio disturbance is likely to
occur. Proper repair and attention
to the condition Of the motor will
eliminate much of this.
10. Battery Charging Devices.
Vibrating, mecury-vapor, vacuum
tube and other form Of battery charg-
ing devices will interfere with radio
reception for several hundred feet.
Much OF this trouble can be elimi-
mated by the judicious use of con-
denser and chokes.
II. Electric Sign Flashers
Electric sign flashers can effect
radio reception for a considerable
distance, depending upon the amount
of current being consumed through
the flasher. One case OF this kind
was eliminated by placing the
flasher inside of metal box, which
was grounded. Trouble from this
source has been observed as far as
500 feet.
tot fnx.