A practical Treatise on Wireless Telegraphy and Telephony, giving Complete and Detailed Explanations of the Theory and Practice of Modern Radio Apparatus and its Present Day Applications, together with a chapter on the possibilities of its Future Development
WIRELESS TELEGRAPHY
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for the mechanical type. One pole of the current is con-
nected to a lead plate placed in a jar containing a mixture
of sulphuric acid and water. The other side of the cur-
rent is connected to a platinum wire placed in a porcelain
tube so that only a small part of the lower end is in contact
with the solution. When the current passes a bubble forms
at the end of the wire shielding it from the liquid, and
thus interrupting the current. The bubble is almost im-
Fig. 39.—Open and closed core transformers.
mediately discharged however and the current allowed
to flow an instant before a new one forms. This operation
is repeated continuously at a frequency sometimes as high
as a thousand per second. An electrolytic interrupter is
both an expensive and a troublesome device. There are
other types of interrupters of value in wireless service but
the limitations of space prohibit any account.
The transformer is acknowledged to be the best prac-
tice as a means of stepping up the voltage of a circuit for
wireless telegraph purposes. Alternating current is nec-
essary to operate a transformer. There are two distinct
types of transformers known as the “open” and “closed
core” accordingly as the shape of the latter is straight like
that of an induction coil or in the form of a hollow rec-
tangle. The closed core transformer consists of two coils