1912 RX Sweeney 0

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}28 WHRELIESS CPI LER APEY,

In the Batsillic system, a path of lesser resistance is
offered to the condenser to discharge via the charging
ciremit than via the condenser discharge circuit. This
is attained by tuning of power circuits, or resonance in
the charging circuits.

The condenser becomes charged, and fora short space
of time the gap offers an casier path for the condenser
discharge than the charging circuit. Vhis is catised
by the pressure from the charging circuit building up by
process of resonance, till the pressure is sufficient to
break down the insulation of the gap. .\s soon as this
takes place, the condenser discharges.

In discharging, a condenser always overshouts its
zero mark, and cemsequently reverses its charge.
When the condenser is) reversed in charee by
its first discharge. a condition is set up wherein a path
of lesser resistance is offered to the encrey stored in the
condenser to discharge via the charging circuiis than via
the spark-gap. Consequently, there are no oscillations in
the condenser discharge circuit, merely one vigorous
oscillation.

This, then, is what is meant by unidirectional mpulse
excitation, which is the distinctive feature of the Balsillic
system.

The receiver used generally in coast stations is that
known as Type 3 tshown diagrammatically in) Iigs. 38
and 39). This is used in conjunetion with ‘Type 4 Cinter-
ference rejector), illustrated in [igs. 60 and Ol.

Vhe capacity of the variable condensers emploved is
02 microfarad cach.

Vhe arrangement of the cireuits will be seen by re-
ference to the diagrams.

The standard detector is the crystal type. Formerly,
the ‘Bornite and Zincite combination was emploved, but
tt was superseded by the introduction of the specially-

BALSILLIE SYSTEM. 129

prepared iron pyrites, which gave vers satishtctory: re
sults. In many stations the latter has been disearde |
in faver of Australian galena, which has proved to be the
Most sensitive of all crystal detectors. Phe principal
objection to galena is that it is easily knocked out vl
adjustment; but, notwithstanding this, it has became very
popular amongst operators. .

It should be noted that in Commonwealth stations the
valve type of receiver is now in general use, but the
erystal detector is also installed,