Improvements in Apparatus for Producing Musical Sounds by Electricity.
Year: 1896

page_text: Date of Application, 26th May, 1896-Accepted, 22nd Aug., 1896
COMPLETE SPECIFICATION.
Communicated from abroad by GEORGE BREED, and CHARLES ADDISON
BRAGG, both of S.E. corner of Broad and Chestnut Streets, City and County
of Philadelphia, State of Pennsylvania, United States of America, Electrical
Engineers.]
Improvements in Apparatus for Producing Musical Sounds by
Electricity.
1, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 322, High Holborn, in the County of Middlesex,
6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in the County
of Lancaster, and Lower Temple Street, Birmingham, in the County of Warwick,
Civil Engineer, do hereby declare the nature of this invention and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement :-
My invention relates to the production of musical sounds by electrically vibrating
a sonorous body and, by means of the sound waves thus set in motion, vibrating a
current pulsating device which pulsates the exciting current synchronously with
the vibrations of the sonorous body.
The microphone is an example of a device which may be vibrated or whose
electrical resistance may be rapidly varied by sound waves impinging upon it and,
when placed in circuit with an electro-magnet in position to attract a sonorous
body and thus cause it to vibrate, the microphone will cause the exciting,current
to pulsate in unison with the vibrating sonorous body.
The advantage resulting from the isochronous action of the attracting force and
the vibrating sonorous body is well known to those skilled in the art, and it is the
object of my invention to embody this principle of action in a musical instrument
in the most effective form.
By my mechanism the intensity and distribution of the current in an electro-
musical instrument may be controlled, and the adjustment of the current pulsating
device automatically effected.
The performer is also enabled to determine at will the length of time any tone
of the scale is to be sounded, and to elect which tone shall be prolonged and which
shall be affected by the usual mechanical influences only.
The accompanying drawings illustrate the principles of my invention and the
mechanism I have invented for carrying them into effect.
Figure is a diagrammatic view of iny mechanism applied to a piano-forte;
Fig. 2 illustrates the action of an element of the system;
Fig. 3 is a diagrammatic view of my mechanism applied to an upright piano;
Figs. 4 and 5 illustrate automatic adjusting contact devices.
Referring to Fig. 2 the part K illustrates the key of a piano pivoted in the
usual way, and provided with a projection d. When the key is depressed the
part d rises and moves the spring switch a from contact with the part c (where it
is held by its own resiliency) into contact with the part b, thus closing an electric
circuit. A current now passes from the battery B in the direction of the arrow,
through the wire W, contact b, wire w, electro-magnet M, rheostat R, spring_o,
pulsating device C (which is thrown into action by means of its shunt magnet L)
and theuce back to the battery.
The depression of the key has produced the usual vibration of the wire S,

page_text: through the action of the hammer H, and the damper D: The excited electro-
magnet M continues this vibration as long as the key is held down and the circuit
closed.
The sound waves set in motion by the vibrating wire act upon the pulsating
device C, thus varying the electrical resistance, whereby the current is made to
pulsate isochronously with the vibrations of the wire.
The rheostat R, in the main circuit as shown in Fig. 2, or arranged in shunt as
shown in Fig. 1, is operated from the pedal F, through the rod q, and spring o, to
vary the strength of the current thereby varying the volume of the tone.
Referring now to Fig. 1, K, K1, K2, K³, K, K, represent keys of a piano;
a, a, a, a, a, a, represent corresponding interlocking spring switches normally
held by their own resiliency against the contacts c, c', c², c³, c, c, respectively,
and, when the keys are depressed, against the contacts b, 61, 62, 63, 64, 6, respectively.
Hence it is seen each key controls an interlocking two-way switch.
Wires wo, w¹, w, 103, 10, 10 lead to electro-magnets M, M1, M2, M3, M*, M³,
thence to the return wires 1, 2, 3, 4, 5, 6. A branch wire W' leads from the main
circuit, by means of which and the push rods P, P1, P2, P3, P4, P5, current may
enter at points farther down the key board as will appear later.
The several keys have their corresponding wires or strings S, S', S³, S³, S*, S³,
hammers H, H', H, H, H, H, and dampers D, D', D2, D3, D4, D³.
If now the key K2 be depressed, thereby bringing parts a2 and 12 into contact and
thus closing the corresponding circuit, a current will pass from the battery through
the circuit W, a, c, a', c¹, a², 12, w², electro-magnet M2, return wire 3, 2, 1, pulsating
device C, and wire W2 back to the battery.
The vibrations of the string S* produced by the hammer H2 are continued by
the action of the excited electro-magnet so long as the key is held down.
If while the key K2 is depressed a key as K' be depressed, the corresponding
string S is subject to the usual mechanical influences only. For the current which
would excite the electro-magnet M' were the higher keys dormant, has been switched
through the electro-magnet M² thereby cutting M out of circuit.
Thus it will be seen that the highest tone only of those being sounded is capable
of being prolonged.
If while the keys K2 and K are depressed it is desired to prolong the vibrations
of any string, as S; which is beyond S and S', the push rod 1 is thrust in making
contact with the wire W₁ A current now passes through the circuit W, P,
as, o, u, electro-maguet M, back to the battery through the return wire 6, 5, etc.
By thrusting in all of the push rods each string of the instrument may be made
subject to electrical influence independently of the action of the rest of the system.
I have devised means for pushing in all of these rods at once which means I have
not deemed it important to show here.
Referring now to Fig. 3 the string S is brought under magnetic influence
and its vibrations prolonged by pressing down the key K, whereby the circuit is
closed and the electro-magnet excited. Here, as already explained, the sound
waves produced by the vibrating string act ou the pulsating device C to vary
its resistance.
Fig. 4 shows a self adjusting pulsating device. The carbon J is attached to the
end of a spring F¹ secured to the .block e, and normally rests against the sounding
board S. Set screws g permit the adjustment of the block in relation to the
block e, and by consequence the adjustment of the carbon I with relation to the
carbon J.
The exciting current reaches the binding post B₁ through the wire 1, thence
passing through the wire wol, pendulum A., (secured to the block f), arm G,
carbon 1, across the point of contact to J,. thence through the spring F, wire w
binding post B" and wire Wto the battery.
The device is normally adjusted, with the contact points 1. and J slightly
separated. The current from the battery therefore excites the shunt magnet L
which draws them together, and holds them in more or less. intimate contact as

page_text: long as the current flows. The wires 2012 and 2013 connect this shunt magnet
with the battery and when excited this magnet attracts the armature A' of the
pendulum A, thus moving the pendulum and with it the part I into closer relation
with the part J.
The shunt magnet may be adjusted to the proper position by means of the thumb
screw connected to the block f.
By thus adjusting the parts the desired pressure may be obtained so that the
vibrations of the sounding board s may most readily affect the resistance of the
circuit at that point.
The end of the pendulum is submerged in a liquid contained in a cistern E,
the liquid acting to check or damper the oscillations of the pendulum.
Figure 5 shows a device analogous to that shown in Fig. 4. In this instance,
however, the main current passes from the binding post B₁, through the electro-
magnet L', wire 10, pendulum A, arm G, contacts I and J, through the coiled
spring F, and the wire w", to the binding post B. In this instance tbe
part J, resting against the sounding board s, is supported on a coiled spring secured
to the block f¹.
By a simple reversal of the wiring of the electric system I am enabled to sound
the lowest tone at will while the highest tones are subject to the usual mechanical
influences only.
I do not wish to be understood as limiting myself to the use of spring contacts
in the system of switches which control the distribution from the key board, as
I may use equivalent circuit making and breaking devices such as conductors
dipping into mercury cups.
Having now 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 :-
1. A series of musical strings, in combination with a series of electro-magnets
arranged in parallel and connected with a source of electric energy, and a system
of two-way switches controlling the current to the electro-magnets, substantially
as shown and described.
2. In a piano, in combination, a system of keys, a system of interlocking
two-way switches, a system of electric circuits and electro-magnets, a current
pulsating device and a series of musical strings or wires, substantially as shown
and described.
3. In combination with the key of a musical instrument, an electric circuit, an
electro-magnet, a second electric circuit, a two way switch which diverts current
from the first to the second circuit, a sonorous body, and a vibrating contact,
substantially as shown and described.
4. In combination with the key of a musical instrument, an electric circuit, an
electro-magnet, a second electric circuit, a two-way switch which diverts current
from the first to the second circuit, a vibrating body producing sound waves, and
means for synchronizing the vibrations of the sound producing body and the
pulsations of the electric current substantially as shown and described.
5. In a contact device for a musical instrument, in combination with an electric
circuit, a pendulum having a contact point I, a spring having a contact point J,
and a cistern containing a liquid, substantially as shown and described.
6. In a contact device for a musical instrument, in combination with an electric
circuit, a pendulum having a contact point I, a spring having a contact point J,
and an electro-magnet, substantially as shown and described.
7. In a contact device for a musical instrument, in combination, an adjustable
block, a pendulum having a contact I, a spring having a contact J, a cistern
containing a liquid, an electric circuit, and an electro-magnet, substantially as
shown and described.
8. In a contact device for a musical instrument, in combination with an electric
circuit, an oscillating body having a contact point, means for damping or checking

page_text: the action of the oscillating body, and a spring provided with a contact point,
substantially as shown and described.
9. In a musical instrument and in combination with a sonorous body, an electric
circuit having a wire W¹, a push rod P', a switch a, a contact 65, an electro-magnet
and a vibrating contact, substantially as shown and described.
10. In a system of electric circuits adapted for use with a musical instrument, a
series of two way switches, a series of push rols, and a branch conductor W',
substantially as shown and described.
11. In a musical instrument, in combination with a series of sound producing
bodies, a system of interlocking two way switches, and a system of electric circuits
and electro-magnets, substantially as shown and described.
12. In a contact device, in combination with a musical instrument, an electric
circuit, an oscillating body having a contact point, and means for damping
or checking the action of the oscillating body, substantially as shown and
-described.
13. In a contact device, in combination with a musical instrument, an electric
circuit, an oscillating body having a contact point, means for damping or checking
the action of the oscillating body, and an electro-magnet, substantially as shown
and described.
.14. In a two way switch of a musical instrument in combination the resilient
spring a, the contact c, and the contact b, substantially as shown and described.
15. In a musical instrument, a two-way switch, comprising a pair of contacts,
and a resilient member which is normally held by its own resiliency in engagement
with one of the said contacts and adapted to he moved into engagement with the
other of the said contacts, combined in interlocking relation with a second similar
two-way switch, substantially as shown and described.
16. In a contact device, in combination with an electric circuit, an oscillating
body having a contact point, means for damping or checking the motion of the
oscillating body, and a second contact point mounted on the sound board of a
piano, as shown and described.
17. In a musical instrument a contact device comprising an oscillating body
having a contact point, means for damping or checking the motion of the oscillating
body, a second contact point, and an electro-magnet placed in shunt relation with
the said contact points, substantially as shown and described.
18. In a contact device, in combination with a musical instrument, an electric
circuit, an oscillating body having a contact point, and electrical means for
automatically effecting the desired mean pressure, substantially as shown and
described.
Dated this 26th day of May 1896.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.