Improvements in Electric Signal Circuits.
Year: 1890

page_text: Date of Application, 20th May, 1890-Accepted, 23rd Aug., 1890
COMPLETE SPECIFICATION.
Improvements in Electric Signal Circuits.
I, ORLANDO WILSON HART, of 23 Winter Street, in the City of Fall River, in the
County of Bristol, and State of Massachusetts, United States of America, Electrician,
do hereby declare the nature of my invention for "IMPROVEMENTS IN ELECTRIC
SIGNAL CIRCUITS," and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement, reference
being had to the accompanying drawings forming part of this :-
This invention has reference to an improvement in automatic fire-alarm and other
signalling circuits, and consists in providing the main circuit with a magnet of bigh
resistance connecting a shunt circuit with the main circuit and providing the shunt
circuit with a magnet of lower resistance, as will be more fully set forth hereinafter.
The object of this invention is to so construct a signal circuit of the character
inentioned, as to make it impossible to send a signal through the main magnet save
by operating one of the stations as hereinafter described.
The accompanying drawing shows a diagrammatic view of a signal circuit
embodying my invention.
A represents the battery, B, B1, B" are stations. C, C, C are the top contacts,
D, D, D are the straps or levers. E, E¹, E, are the lower contacts." F is the
lower contact wire to the battery. H is the main signal magnet. J, Jare the wires
leading from the top contact to the next strap above. K is the wire leading from
the last top contact to the trouble magnet. L is the wire leading from the trouble
magnet to the battery. N is the wire leading from the main magnet to the battery.
P is the wire leading from the strap of the first key to the main signal magnet.
To make or transmit a signal from any station, say station B, for example, a button
is pressed so as to make bottom contact at E with the strap D, thus opening the
circuit leading through the trouble magnet I and sending the battery circuit through
the main signal magnet H, giving the necessary signal-said circuit then consisting
of wires F, N, P, and strap D. In case of "trouble" arising from short circuits and
like causes, the current will flow around the short circuit, but as the resistance of the
main magnet H is not less than five times greater than the resistance of the trouble
magnet I, only one-fifth of the current will flow through magnet H, which is
insufficient to operate it and give the signal, while the remaining four-fifths will pass
through various stations B, B, B", and wire K to the trouble magnet I and through
wire L to the battery, giving the alarm at the trouble magnet and communicating thus
the fact that there is trouble on the line.
It will thus be seen that closing the circuit anywhere excepting at stations alarms
the magnet I.
Having cow particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
In an electric signal circuit, the combination of the main circuit consisting essen-
tially of the wires N, P, F, straps D, D¹, D", contacts E, E¹, E", and signal
magnet H; and the shunt circuit described consisting essentially of the wire I.
connecting the main circuit between the battery and the main signal magnet, the
trouble magnet 1 and wire K connecting with the main circuit at the top contact of

page_text: the last station on the line, the resistance of the main magnet being much greater than
the resistance of the trouble magnet, substantially as set forth.
Dated this 17th day of April A.D. 1890.
ORLANDO WILSON HART.
Signed in presence of :-
FREDERICK O. DODGE.
H. IRVING NICHOLS.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.