The Washington herald., 1922-10-22
HEAVY CURRENTS
DAMAGE DELICATE
MAGNET IN CASE.
Amateurs May Remagni-
tie Phones in Home
BY Simple Process.
WATCH RECEIVERS
Standardization of Head Sets
By Manufacturers VIII
Prove Aid.
w ATCH RECEIVERS

Most operators do not appreci-
ate the value Of telephones In their
sets. and the phones are dropped
on the table and floor and other
wise carelessly handled. Telephones
are usually of the watch case type.
A permanent magnet is placed in
the bottom Of the case Violent
knocks will demagnatize this mag
net and the telephones will lose
their sensitiveness.
When used with audion detectors
or ampliffers IL Is necessary that
the correct terminal of the tele-
phone cords be connected to the
positive side of the ''B" battery. II
electric currents go through tele-
phone receivers in such a direction
that the electro-magnets produce
magnetism irsfopposition to that of
the permanent magnet, the tele-
phone receivefs will be gradually
made weaker as the permanent
magnet loses its strength.
Too Mu = Current Hurts.
Telephone receivers are damaged
by allowing too much current to
flow in the windings. 1t must be
remembered that only a fractional
amount of current passes through
the telephones during reception OF
radio programs So care must be
used to see tnat only the proper
currents 80 through tAe telephones
and they snOuld not DC used for
testing purpOSes.
Tubes Iurnish a large amount of
direct current into the telephones
=. IN, -
tton, the receivers will gradually
lose tne.r magnetism. To counter
act this. be sure it is in such a di-
rection that il strengthens the per-
manent magnet.
This can be deter mined by hold
ing the finger On the Diaphragm
hsntly when connecting the tele-
phones in the circuit If dia-
pnrasm goes in further toward the
pole pieces the magnetism is in
creased. winch IS correct. Ii it does
not. reverse the telephone connec-
tIons- To facilitate matters. the
prominent manufacturers are stand
ardizlns head sets by furnishing
receiving corap with a red thread
running through one of the cords.
which should be connected to the
positive side of the ''B" battery.
III you use Jacks. IL will be nee
essary to connect your telephone
CORDS to the part of the jack max
ing contact with the positive plate
lead.
How to Magnetixe Them.
Should the telephones become de-
magnetized 1t is possible to remag-
netizs them at home very easily.
sVra ha il
cells or storage battery and four
or five feet Of insulated No. "a COP
per wire. TaHa the telephone apart
carefully. so rs not to break the
fine wirs with which the magnets
are wound. In the bottom will be
found a horseshoe shaped piece of
iron. which is the permanent mag
net.
Wind about ffty turns of the wire
ON this. beginning near one end and
ending the same distance from the
other. Wind in the sam. direction
throughout. The ends of the wire
are then connected with a six-volts
supply. but only for short time.
after the current is off try the hold
inE power of the matnet to see if
ii has been magnetized.
The first test may not have been
long enough; il net try it again, but
he sure and connect the same wires
to the same battery terminals on the
second tsst. for If you do not IL will
COunteract your previous efforts.
The telephone is then reassembla ed
and the red cord Is connected to the
positive terminal OF the plate bat
terry 1t il does not cause the dia-
phragm to be pulled in farther By
the combined Dcrmanent and electro
magnets reverse the cords at the
telephones.
With d little care telephone re-
ccivcTs will give excellent results in
continuous service + T years. The
writer has an old pair Of wireless
speciality telephones with adjustable
electro magnets that have been in
,,eady use since 1909. Telephones are
th. most reliable part of your set
" hen given pTOp-r treatment