Evening star., 1922-06-13

waterproof paper. This may be good
quality white paper soaked in shellac
Sheets eh ei,ro around A'as' the long tsix-inchS
sides of the core and wind on the
primary wire. This should be of No.
% double cotton covered OF enameled
copper wire, and should have 225
| turns on each side of the core as
shown in figure 2.
Place waterproofed paper over the
| windings and wind on the secondary.
| This should be of No. 80 wire wound
164 turns on each side and with
| trated.
May Use Fruit Jars
In order to smooth out the direct
! current from this transformer you
will require rectifiers c. c., which are
simple and easy affairs to make.
Ordinary fruit jars will, serve for the
containers, and the number you re-
jars and the capacity of the cleo
| trodes. Try at least four and add
more If needed. The jars should be
filled nearly full of saturated solu-
tion of borax and water. The boTax
should be mixed with hot water in
some receptacle. and stirred until dis
solved. Then continue adding borax
until no more will be dissolved. AL
low the solution to settle, and pour
| the clear liquid into the rectifiers,
I L..
sediment or undissolved borax in the
jars.
| The electrodes are strips of sheet
! lead and sheet aluminium about one
leighth of an inch thick and one-inch
wide. A sheet of lead and a sheet of
aluminium are used in each jar and
are connected alternately as shown.
! To secure the strips in position in the
jars, they may be merely bent over at
the ends and hung on the edges of
soldered to them, Fig. ga. It is far
better, however, and makes a neater
| job to have the plates attached to
covers as shown in Fig. BIB. These
covers need not fit the jars, but may
be of wood fiber or hard rubber, cut
pletly cover the tops. This prevents
the borax solution from evaporating
and avoids dust and foreign matter
| falling into the jars. 1t also gives a
good support to the strips. These are
merely bent at right angles near one
| binding screws such as may be OBJ
! tained from old dry batteries.
By placing the strips the right dis
| tance apart they will bear against the
sides sides Of 1.-The the jars sand and prevent the tops
! these rectifiers, the plates must be
formed" which is easily accomp-
| lished>by connecting them to an or
| dinary lighting circuit and letting the
current flow through for several
| hours From time to time, the liquid
should be replenished by adding pure
water only and as the aluminium
strips become thin and perforated
| they must be replaced with new ones
| This is the only care or expense con-
| nected with the rectifiers after they
are once made.
The other set, in which a single
transformer is used for both plate
| and fllament circuit, is practically
| identical to-. Fig 4. aside from the
| transformer. This is made exactly as
| described, except that a third or fla
! ment winding. must be put on. the
short sides Of the rectangular core
| using No. Ia wire and putting on
twenty-six turnssdivided between two
| sides. Fig. s, and, Of course, removing
the twine and using the waterproofed
paper over the core before winding.
After the transformer is completed
1t is good plan. to wrap all sides
with waterproofed paper and finish
By winding, with adhesive tape.
(cdyfight, 1g22.3 :