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Патент USA US2408590

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Oct. 1, 1946.
A_ w, WELLS
I
2,408,589
APPARATUS FOR PRODUCING ELECTRICAL OSCILLATIONS
Filed May 15. 1942
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Oct; 1, 1946-
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A; w. WELLS
2,408,589 .
APPARATUS FOR PRODUCING ELECTRICAL dscILLATIoNs
Filed May 13. 1942
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2,408,589
Patented Oct. 1, 1946
UNITED STATES PATENT OFFICE
2,408,589
APPARATUS FOR PRODUCING ELECTRICAL
OSCILLATIONS
Alvin W. Wells, Chicago, Ill., assignor of one-half
to Jewel W. Wells, Decatur, Ill.
Application May 13, 1942, Serial No. 442,804
3 Claims. (01. 25041.5)
1
The present invention relates to a system or
method and apparatus for the production of'clec
trical oscillations, and relates more particularly
to an electrical system which uses as a source of‘
2
buffer ampli?ers for each glow discharge oscil
lator to thereby separate the electrical circuits
of each oscillator from one another when two
or more of the oscillators are simultaneously con
nected or keyed to the output. Since the elec
trical instrument may contain from sixty-one to
several hundred oscillators, in order to afford a
It is an important object of my invention to
satisfactory tonal range, the practice of using
provide a method and apparatus for'producing
separate oscillation or buffer ampli?ers for each
electrical oscillations as obtained from one or
more glow discharge oscillators which may be ad 10 oscillator would render the musical instrument
very expensive and complicated to manufacture.
vantageously and economically used in the manu
By my invention, I have provided a method
facture of an electric musical instrument, such
and apparatus for coupling two or more glow
as an electric organ.
'
discharge oscillators simultaneously to an output
While the invention is hereinafter described in
circuit without affecting the individual oscillation
connection with a musical instrument, it will be
electrical oscillations, a plurality of glow dis
charge oscillator circuits.
understood that the invention contemplates pro
frequency of the separate glow discharge oscil
lators. I have provided a photo-electric system
which will be responsive to the glow or ?uctuat
tion of electrical oscillations as obtained from one
ing light emitted by the glow discharge tube of
or more glow discharge oscillators which may be
capable of general application.
20 the oscillator circuit. The light from the glow
discharge tube ?uctuates at the exact frequency
It is well known that a glow discharge oscillator
of the oscillating circuit. By optically coupling
may be employed to produce electrical oscillations
the glow discharge oscillator to the photo-electric
‘varying in frequency from less than 1 cycle per
system and associated ampli?er for reproducing
second to more than 30,000 cycles per second. It
has been attempted to employ such a glow dis 25 the electrical signal into audible sound, I have
provided a system whereby two or more glow
charge oscillator to produce electrical oscillations
discharge oscillators may be connected at the
of audio frequencies capable of being used in a
same time to the output without affecting the
musical instrument. Great difliculty has been
individual frequencies of the oscillator circuits.
encountered‘, however, when attempting to use a
This photo-electric system of coupling the glow
plurality of glow discharge oscillators to produce
discharge oscillators to an output circuit is very
a complex audio oscillating signal, such as would
economical to manufacture.
be obtained when playing two or more notes
It is, therefore, a further object of my inven
simultaneously in the production of a harmonic
tion to provide a method and apparatus of op
passage. To produce a harmonicl'pa'ssage, it was
tically coupling two or more glow discharge oscil
necessary to electrically connect two or more
lators to a photo-electric reproducing circuit for
oscillator circuits to an output ampli?er and
translating the oscillation frequencies generated
speaker. The di?iculty encountered was appar
in the oscillator circuits to audible frequencies.
ently due to the fact that the electrical coupling
viding a method and apparatus for the produc
It is a further object of my invention to provide
oscillators would usually cause the oscillators to 40 a method of producing a complex electrical os
cillation resulting from the effect of a simul
tie in ‘together and behave as a single oscillator.
tanecus exposure of two or more fluctuating light
That is to say, the individual frequencies of the
or connection between two or more glow discharge
individual glow discharge oscillators, when elec
trically coupled together, would be degenerated
sources as obtained from two or more glow dis
charge oscillators upon a photo-electric reproduc
to a single new‘frequency and would not be a, 4-5 ing system.
It ‘is still a further object of my invention to
complex frequency resulting from the simultane
provide a musical instrument employing the
ously superposi'ng of the two individual frequen
optical system of coupling the glow discharge
cies upon each other. Therefore, it'was apparent
oscillators to the photo-electric reproducing sys
that two or more glow discharge oscillators could
tem having means associated with a key board
not be electrically coupled together at the same
for selectively exposing each of the glow dis
time to produce a harmonic passage because of
the fact that the speci?c frequencies of the indi
charge oscillators to' the photo-electric reproduc
vidual oscillators were changed.
Attempts have‘ been’ made to overcome this
ing system.
It is another object of my invention to pro
di?iculty‘ by employing separate oscillation or 55 vide' almusical instrument employing the optical
2,408,589
3
system of coupling the glow discharge oscillators
to the photo-electric reproducing system having
means associated with a key board for selective
ly exposing each of the glow discharge oscillator
tubes to the photo-electric element and so con
structed that the amount of optical exposure of
the glow discharge tube to the photo-electric
element will be proportional to the amount of
pressure applied to the clavier key of the key
board, thus offering a means of varying the dy
namics of the individual electrical signals and en
abling the production of percussion effects, or the
like.
It is still a further object of my invention to
provide a musical instrument employing the op
tical system of coupling the glow discharge os
cillators to the photo-electric reproducing system
in which the glow discharge oscillator circuits are
provided with a means for periodically raising and
lowering the oscillation frequencies to thereby
produce a vibrato effect.
Further objects and advantages of my inven
tion will be apparent by reference to the follow»
ing speci?cation and drawings, in which:
Figure 1 is a schematic diagram of a conven
tional glow discharge oscillator using a neon glow
tube;
Figure 2 is a schematic diagram of a glow dis
charge oscillator in association or optically cou—
pled to a photo-electric reproducing system com-i
prising a photo-electric cell and a photo-electric
ampli?er of standard design;
‘ Figure 3 is a schematic diagram of a number
of glow discharge oscillators provided with a con:
mon source of applied voltage and showing a
means for periodically raising and lowering the
applied voltage to provide a tremolo or vibrato
effect;
Figure 4 is a diagrammatic showing of one form
of apparatus for selectively exposing the glow 4
discharge tube of an oscillator circuit to a photo
electric cell by means of an optical shutter in
connection with a clavier key;
Figure 5 is a schematic diagram showing a plu
rality of glow discharge oscilators and diagram
matically showing a single photo-voltaic type
photo-electric element responsive to the glow of
any of the glow discharge tubes in the circuit;
Figure 6 is a cross-sectional view or the photo~
voltaic type cell diagrammatically shown in Fig
ure 5;
‘
circuit. Therefore, the glow discharge oscillator
circuit may be tuned to different oscillation fre
quencies by varying the value of any of these
constants, such as the capacity, resistance, and
applied voltage. If the voltage is maintained
constant, the condenser or resistor values may
be varied to change the oscillation frequency.
I have found, by experimentation, that the best
practice for tuning the oscillator to desired fre~
- quencies is to adjust the values of the resistor
2 for the lower frequencies included in the range
up to 1,000 cycles per second and to adjust the
value of the condenser 4 for the higher frequen
cies included in the range of 1,080 cycles per sec
ond up to the highest frequency desired.
In Figure 2 of the drawings, I have shown a
schematic diagram for a glow discharge oscil
lator that is optically coupled to a photo-electric
reproducing system. The glow discharge tube 5
is connected in series with the resistor 6 and the
applied voltage as obtained from the voltage di_
vider l. A condenser 8 is shunted in parallel
with the resistance 6. By adjusting the resist
ance 6 or the condenser 8 as described above in
connection with Figure l, the frequency of 0*‘
cillation in the oscillator circuit may be changed.
It is a function of the glow discharge oscillator
tube 5 that the light or glow emitted by the tube
when oscillating in an oscillating circuit will ?uetuate at a frequency which is identical to the
frequency of the oscillating circuit.
Optically
conected to the glow discharge tube 5 is a photo
electric cell or other photo-electric responsive
element 9. This photo-electric cell is provided
with a suitable photo-electric ampli?er which I
have shown in Figure 2 of the drawings to be of
the resistance coupled type. Plate, grid, and bias
resistors R, together with coupling and by-pass
' condensers C, triode tube Hi, and output trans
former T, constitute a schematic showing of a
standard type ‘of resistance coupled ampli?er.
It should be understood that any other desired
form of ampli?er, such as a transformer-coupled
or a direct~coupled ampli?er, may be used in
place of the resistance-coupled ampli?er which I
Figure 7 is a diagrammatic showing of a modi
?ed form of key arrangement for selectively ex
posing the glow discharge tube of an oscillator
circuit to a photo-electric cell in which the de
gree of exposure will be proportional to the
amount of pressure on the key or the relative
depressed position of the key;
4
age, cause the circuit to oscillate, and the fre
quency of the oscillation may be varied by ad
justing the constants of the circuit, such as the
resistor 2 and the condenser 4. The frequency
of the oscillation produced is aiTected by the
capacity, resistance, and applied voltage in the
‘
Figure 8 is a diagrammatic showing of still
another modi?ed form of key arrangement to i
provide pressure responsive dynamic control of
the individual tones produced; and
Figure 9 is a front detail view of the optical
shutters shown in Figure 8.
Referring to the drawings, Figure 1 is a sche
matic diagram of a conventional glow discharge
oscillator circuit having a neon or other form of
have shown. It will be apparent that any de
sired number of photo-electric cells may be con
nected to a single ampli?er.
The operation‘of the electrical system shown in
Figure 2 of the drawings and described above is
as follows: When the oscillating circuit is ener
gized, the glow discharge tube 5 will emit a ?uc
tuating light corresponding in frequency to the
frequency of the oscillating circuit in which the
glow discharge tube is connected. The ?uctuat
ing light emitted by the glow discharge tube 5 is
directed upon the photo-electric element 9 and
will cause the photo-electric element 9 to trans
late the light impulses into a ?uctuating or os
cillating current which will be coupled to the
glow tube I connected in series with a resistance
photo-electric circuit by the resistance-coupled
preampli?er and transformed by the output
2 and a source of direct current, such as a bat
transformer T to the proper impedance desired
tery 3 or the like. A condenser 4 is placed in par~
allel with the resistor 2. A make and break switch
S is shown to selectively energize the oscillator.
As is well known, a glow discharge tube‘in
connection with a circuit,‘such as described in
Figure 1, will, when energized by an applied volt
for a power ampli?er or the voice coil of a loud
speaker (not shown). Thus, an electrical system
is provided for coupling a glow discharge oscilla
tor to a reproducing system in which the circuit
for the glow discharge oscillator is electrically
independent of the circuit for the reproducing
caresses‘
r
0
system. With such an arrangement of optical
coupling, it is possible to connect two. or more
glow. discharge oscillators simultaneously to a
photo-electric reproducing system, and. because
6
,
tric reproducing ‘system; and speaker. In opera
tion; the electrical. system for periodically rais
ing and-‘lowering the applied voltage to the oscil
lator circuits is ‘as-follows: The; voltage of 350
the circuits of the oscillators and the circuit of. the
reproducing system are independent, there will
be no electricalcoupling or connection between
the. individual‘ oscillator circuits, and the di?i
volts
appliedacross the voltage divider D which
culties previously encountered, where electrical
drawings andis not electrically contacting the
is comprised of. the resistance segments ll, l2, l3,
andv I4. When the vibrating switch blade I8 is
in the mid-position shown in Figure 3 of the
coupling or connection between the oscillators 10 switch contactsl?sor H; the applied voltage sup
plied to the line H51 in the glow discharge oscilla
was used,.are avoided.
Figure 3 of the drawings shows a plurality of
tors is obtained from the voltage divider D at the
point‘ between. resistance segments l2 and I3.
glow. discharge oscillators provided with a com
The oscillators will then be supplied with a nor
mon source of applied voltage. The appliedvolt
mal amount of applied voltage. When the vi
age for the circuit. shown in Figure 3 is, periodi
callyvaried about a mid-point to obtain a period:
brating switch blade I8 is electrically contacting
ie rise and fall in the frequency of oscillations
the switch contact I5, the resistance‘ 24 will be
produced in the glow discharge oscillator cir
placed in parallel with the resistance segment, l2,
thus effectively reducing the total resistance of
cuits. A voltage divider generally indicated by
D. is divided into resistance segments ll, [2, l3, 20 the resistors I l and I2. and increasing the applied
voltage to’the line l6 and the glow discharge oscil
and M. An appliedvoltage of 350 volts is sup
plied to the voltage divider D. At the point be
lators. The frequency of the oscillators will then
be raised above, the normal. When the vibrating
tween the resistances. H and 12, the switch con
switch blade I8 is in electrical contact with the
tact I5 is connected, and at the point between
the resistances l2 and IS, the glow discharge os
cillators are connected by means of the line l6.
switch contact [1, the resistance 24 will be con
nected in parallel with the resistance l3, thus ef
At. the point between resistances, l3 and M, the
switch contact H is electrically connected. The
switch blade l8is pivoted at, 19 and is connected
fectively reducing the amount of resistances l3
by means of the pitman arm 20 to a crank 2| on
the shaft ofv a small electric. motor 22,. The small
lines Hiv and 25 of the applied voltage for the glow
discharge oscillators, the applied voltagev to the
electric motor is preferably of the synchronous
type which will run at constantspeed, or. it may,
if desired, .be providedwith suitable means to vary
line 16 and the oscillators will be reduced. There
fore, the frequency of the oscillators will then be
lowered below the normal. Thus, it will be seen
the speed, and it will be apparentthattheswitch
blade l9. willbe periodically connectedat regular
that the vibrating switch blade 18, periodically
contacting the switch contacts l5‘ and I1, will
intervals with the switch contacts l5. and I‘! when
the electric motor is inoperation. Theswitch
blade I8 is electrically connectedthrough an on
or off switch 23. and resistor 24t0, the line l6 sup 40
cause the appliedvoltage to the line IIS and the
glow discharge oscillators to be periodically raised
plyingapplied voltage to. the glow discharge os
cillator circuits. The glow discharge oscillator
circuits which are connected to the common
source ofapplied voltage, as supplied to the line
I76 .and the ground connection 25, are provided
witha number of glow discharge tubes 26,. It
will benoted that. some of the glow discharge
tubes. 26 are provided with variable resistances 21_
to adjust the. frequency of the oscillating circuit
and thereby the frequency of the fluctuating
light emitted by the discharge tube, while others
of the glow discharge tubes are provided with
variable. condensers 2B for adjusting the fre
quency of. the oscillations and the ?uctuating
light. As previously mentioned, the variable
resistor. 21 is adjusted in the oscillating circuit
when the oscillator is tobe tuned to lower fre
quencies, whereas the variable condenser 28 is
adjusted when tuning the oscillating circuit to
and I4. As the resistances I3 and I4 are part of
the voltage divider and are connected across the
and lowered about a normal. When the switch
blade i8 is in the position shown in Figure 3 and
not contacting the electrical contacts 15 and I1,
the applied voltage will be at a midpoint because
of the fact that the resistance 24 is not electrical
ly connected-into the circuit. It is important that
the applied voltage common to all of the oscilla
tor circuits be varied above and below a normal
or mid-point as this prevents the illusion of the
musical instrument'going out of tune when the
vibrato is turned on or oif. A fixed condenser 29
is shown across the output of the voltage varying
device to eliminate any undesirable oscillations in
the glow discharge oscillators, due to the sparking
of the switch contacts I5 and H with the vibrat
ing switch blade l8.
In Figure 4, I have diagrammatically shown
oneform of apparatus for selectively exposing the
?uctuating light from the glow tubes to a photo
electric element. Mounted within the lightproof
box 30 is the photo-electric cell 31 and neon
higher frequencies.
60 glow tube or its equivalent 32. The condenser
As the oscillation frequency of the glow dis.
33, and resistor 34 for the glow discharge oscil
lator circuit are also mounted within the light
charge oscillator is a function of the resistance
capacity and applied voltage, it will be apparent
proof box. A thimble 35 encloses the glow tube
that varying the applied voltage will vary the
32 and is provided with an aperture or window
36. Positioned'in front of the window 36 is a
frequency of oscillations. As shown in Figure 3,
shutter element 31 pivoted on the spring arm 38
a plurality of glow discharge oscillators are pro
bolted to the lightproof box at 39. A connecting
vided with a common source of applied voltage.
rod in is connected to the spring arm 38 of the
An electrical system is also shown in Figure 3
shutter 31 and passes through the lightproof box
and described above for periodically raising and
to
connect with the'clavier key 4| mounted upon
lowering the applied voltage about a mid-point, 70
the spring arm 42. When the clavier key 4| is
so asto periodically raise and lower the oscilla
depressed, as shown in the dotted lines, the shut
tion frequencies of the oscillator circuits, and
ter 31 will be removed from in front of the window
thereby produce a vibrato effect which will be au
36, allowing the ?uctuating light from the glow
dible when the fluctuating light from the glow
discharge tubes is interpretediby the1-photoeelec-v 75 discharge tube 3.2 toimpinge upon the elements
2,408,589
7
of the photo-electric cell 3|. With this form of
apparatus, it is possible to maintain the glow
discharge oscillators in operation at all times.
Whenever it is desired to optically couple a glow
discharge oscillation circuit to the photo-electric
reproducing system, the clavier key is depressed,
thus removing the shutter from in front of the
aperture and permitting the ?uctuating light
from the glow discharge tube to affect the photo
electric element. Any number of lightproof boxes
containing the photo-electric tube, together with
the glow discharge tube and shutter, may be pro
vided and simultaneously operated, if desired,
without affecting the individual oscillation fre
quencies of the individual glow discharge oscil
lators, since the electrical circuits for the photo
electric reproducing system and the glow dis
charge oscillators are independent of one an
other.
In Figure 5 of the drawings, I have shown a
number of glow discharge oscillator circuits pro
vided with glOW tubes 43 and supplied with a com
mon source of applied voltage of 350 volts. Var
iable resistors 44 and variable condensers 45 are
used to adjust the frequency of the ?uctuating
light given oil by each of the glow discharge tubes
43. A photo-voltaic type of photo-electric ele
ment 46 is provided to receive the ?uctuating
light of the glow tubes 43. The photo-voltaic
type of photo-electric cell is an elongated tube
which can be made of sufiicient length to simul
taneously respond to a large number of glow dis
charge tubes.
If the glow discharge oscillator
circuits and tubes are to be used in the construc
8
lation or tone produced in response to a greater
pressure applied to depress the clavier key.
Referring to Figure 7, a clavier key 52 mounted
upon the spring arm 53 is connected by the con
necting rod 54 to the shutter 55 pivoted on the
spring arm 53. A thimble 5i encloses the glow
discharge tube 58 and has an aperture 59 through
which the light from the glow discharge tube may
pass to the photo-electric cell 69. When the
clavier key 52 is depressed the shutter 55 will be
removed from in front of the aperture 59, thus
eyposing the glow discharge tube 58 to the photo
electric cell 60. It will be apparent that the
amount of exposure or uncovering of the aper
ture 59 will be proportional to the pressure ap
plied to depress the clavier key 52. To indicate
the relative depressed position of the clavier key
52, I have provided stops El, 62, and 63 cooperat
ing, respectively, with springs 54, 65, and 66. If
the key 52 is depressed slightly, stop 6i will con
tact spring 64, thus giving an indication of the
position of the key 52 and the relative exposure
of the aperture 59. If greater pressure is applied
to depress the key 52 the stop 62 will engage
spring 65, thus giving a further indication of the
position of the clavier key and the relative ex
posure of the aperture 59. A rest 57 is provided
to indicate to the player when the clavier key
has been depressed all of the way to completely
expose the aperture 59, thus giving the greatest
dynamic volume to the electrical oscillation re
produced through the photo-electric system.
By skillfully playing, it is possible, with the
form of my invention just described above, to ac
tion of a musical instrument, such as an electric 35 cent the individual notes in a passage to any de
organ, it will be necessary to have at least ninety
six glow discharge tubes and associated oscillator
circuits. These glow disharge tubes may be placed
gree desired, producing various musical effects,
such as percussion or pizzicato effects.
Referring to Figures 8 and 9, a slightly modi
in a line within the cabinet of the musical in
?ed key arrangement is shown for the application
strument, and the elongated photo-voltaic type 40 of my invention to an instrument primarily de
of photo-electric cell may be optically aligned
signed for producing percussion effects by pro
with the line of glow discharge tubes. If de—
portionally exposing the glow discharge tube to
sired, however, more than one photo-voltaic type
the photo-electric cell in response to the pres
of photo-electric cells may be used to take care of
sure applied to the key. The clavier key 68 is
all of the oscillator circuits and glow discharge
pivoted at 69 and is provided with a stepped ar
tubes necessary to produce the ordinary range of
rangement of stop positions 10, ll, and ‘i2.
musical notes on a keyboard instrument.
Springs l3’, ‘l4, and 15 are adapted to cooperate,
A cross-section of the photo-voltaic type of
respectively, with the stop positions ‘Iii, ‘II, and
photo-electric cell is shown in Figure 6. An elon
12. A rest 11 is provided for indicating the fully
gated casing 41 is provided with a glass window
depressed position of the key 68. A shutter ele
48. Positioned within the casing is a surface of
ment ‘[8 having an aperture or window 19 is slid
light-sensitive substance 49 deposited on a metal
ably positioned for vertical movement within the
plate 59. An electrical contact or binding post
light proof box 80 and in front of the aperture
5| is connected to the metal plate 50, while an
or window 8| of the thimble 82 enclosing the
other electrical contact or binding post (not . glow discharge tube 83. A detailed front view of
shown) is connected to the light-sensitive sur
the shutter element 18 is shown in Figure 9 of
the drawings. A weight 84 is positioned at the
face 49. The electrical.,contacts of the photo
top of the shutter element 18. When the key
voltaic type of photo-electric cell are connected
68 is struck the lever end 85 of the key will
in the usual manner to a suitable ampli?er.
In Figures 7, 8, and 9 of the drawings I have 60 cooperate with the bottom end of the shutter
element 18 to thrust said element upward, and
shown two modi?ed forms of keying arrange
the intensity of the impact will determine the up
ments for selectively exposing the light of a glow
ward distance which the shutter 78 is moved. If
discharge tube to a, photo-electric element. The
the key 68 is struck sharply the shutter element
use of an optical keying system such as my inven
65 18 will be thrust upward to its full extent, thus
tion employs offers a means for varying the dy
completely exposing the glow discharge tube to
namic volume of the individual electrical oscil
the photo-electric cell. When the key is fully
lations produced by the photo-electric reproduc
depressed, as shown by the dotted lines A’, the
ing system in accordance with the manner in
shutter element 18 will be moved so that the
which the keys are struck. That is to say, I am 70 center line C of the aperture 19 will be in the
enabled to proportionally expose the glow dis
position shown at A to completely register the
charge tube to the photo-electric element in ac
shutter 19 with the window or aperture 8| of the
cordance with the pressure applied and the posi
thimble 82. If the key 68 is depressed to the posi
tion of the manually depressible key to thus give
tion shown in dotted lines at B the center line of
a greater dynamic volume to the electrical oscil 75 the aperture 19 will be in the position shown at
1 2,408,589
10
9
the clavier key M to thus selectively energize the
desired glow tube and oscillator circuit to cause
the glow tube to emit the desired frequency of
fluctuating light for a?ecting the photo-electric
B, thus partially exposing the light of the glow
tube to the photo-electric element. By skillfully
playing with this arrangement the key 68 may be
struck sharply to- momentarily completely ex
pose the‘ glow discharge tube, but due to the
reproducing system.
It is to be understood that the system shown
and described is merely an illustration of the pre
ferred embodiment, and that such changes may
be made as fall Within the purview of one skilled
in the art without departing from the spirit of
the invention and the scope of the appended
weight 84 and as soon as the momentum of the
shutter element v‘I8 is overcome the shutter will
fall to again shield the light of the glow discharge
tube from the photo-electric cell, thus producing
a percussion tone of great initial dynamic volume,
but decaying to a tone of low volume or of no
volume at all. If the player desires, the key 68
may be struck sharply to the position shown in
the dotted lines at A’, and then be released to
the position shown in dotted lines at B’, thus
claims.
I claim:
1. A light sensitive system comprising a plurality
of glow discharge tubes, oscillating circuits con
tinuingly energizing said tubes, means for tuning
momentarily completely exposing the glow dis
charge tube, but subsequently allowing the glow
discharge tube to be but partially exposed. This
each of said circuits to a certain frequency, elec
tric means outside of said oscillating circuits
adapted to respond to the ?uctuating light
is of great importance when the player desires to
cause the volume of the tone to be of great initial 20 emitted by said tubes, means normally shielding
intensity but to decay gradually to a lower volume
said photo-electric means from said light, selec
level and thus prevent an abrupt ending of the
tively operable means whereby said shielding
tone.
means is rendered ineffective as regards the light
I have described above a system for produc
emitted by one or more of said tubes so that said
ing electrical oscillations in which a plurality of
photo-electric means is correspondingly activated,
glow discharge oscillator circuits may be used.
and an ampli?er fed by said photo-electric means.
By optically coupling the individual glow dis
2. A light sensitive system comprising a plurality
charge oscillator circuits to the reproducing sys
of glow discharge tubes, oscillating circuits con
tem, I am enabled to couple two or more of the
tinuingly energizing said tubes, means for tuning
individual oscillator circuits to a single repro
each of said circuits to a certain frequency, photo
ducing system without electrically vconnecting the
electric means outside of said oscillating circuits
individual oscillator circuits to each other. The
adapted to respond to the ?uctuating light
?uctuating light emitted by the glow discharge
emitted by said tubes, a movable shutter associ
tube of the glow discharge oscillator will fluctu
ated with each of said tubes normally shielding
ate at the exact frequency of the oscillation in 35 said photo-electric means from said light, means
the oscillating circuit, and as the photo-electric
for selectively moving said shutters to permit ac
element is responsive to this ?uctuating light, the
tivation of said photo-electric means by the light
electrical signal generated in the photo-electric
emitted by one or more of said tubes, and an am
cell will be identical in frequency to the frequency
pli?er fed by said photo-electric means,
of the oscillating circuit.
.40
3. A light sensitive system comprising a plurality
While I have described above, in connection
of glow discharge tubes, oscillating circuits
with Figures 4 and 7 through 9 of the drawings,
adapted to continuingly energize said tubes, a
mechanical methods of selectively exposing a
common normal voltage supply for said circuits,
glow discharge oscillator to a photo-electric re
producing system, it should be understood that ‘
other means of selectively coupling the oscillator
circuits to the reproducing system may be em
ployed. Instead of maintaining the discharge
tube and oscillator circuit energized at all times
and using an optical shutter to control the cou
means for tuning each of said circuits to a certain
normal frequency, a photo-electric system inde_
pendent of said circuits disposed for energization
by light emitted by said tubes, means for se
lectively controlling such light emission, an am
pli?er fed by said system and means for rapidly
50
cyclically varying the voltage supply between
pling of the glow discharge tube to the photo
above and below normal whereby to cause corre
electric cell, I may provide a switch, such as is
shown in Figure 1 of the drawings, in series with
sponding variations in the frequency of said tubes
the glow tube and its oscillator circuit. This
switch S, shown in Figure 1, may be connected to 55
and thus produce a vibrato effect.
ALVIN w. WELLS.
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