U.S. patent number 3,629,481 [Application Number 05/070,677] was granted by the patent office on 1971-12-21 for automatic chord and rhythm electronic organs.
This patent grant is currently assigned to D. H. Baldwin Company. Invention is credited to David A. Bunger.
United States Patent |
3,629,481 |
Bunger |
December 21, 1971 |
AUTOMATIC CHORD AND RHYTHM ELECTRONIC ORGANS
Abstract
The system provides a conventional electronic organ with
automatic chord accompaniment and/or an automatic rhythm system.
Playing of only one note in a selected octave of the lower manual
produces proper distribution between pedal and manual root, third
and fifth parts of a chord in any one of five rhythms with rhythm
percussive effects if desired. The pedal and/or manual notes may be
rhythmically pulsed or selectively converted to continuous mode. A
touch bar is provided to convert from major to minor chords.
Playing of two notes defeats the chord accompaniment. Playing of
three notes causes the organ to revert to conventional operation.
Playing of a single note always produces a downbeat.
Inventors: |
Bunger; David A. (Cincinnati,
OH) |
Assignee: |
D. H. Baldwin Company
(Cincinnati, OH)
|
Family
ID: |
22096734 |
Appl.
No.: |
05/070,677 |
Filed: |
September 9, 1970 |
Current U.S.
Class: |
84/713; 84/715;
984/347 |
Current CPC
Class: |
G10H
1/38 (20130101); G10H 1/40 (20130101) |
Current International
Class: |
G10H
1/38 (20060101); G10H 1/40 (20060101); G10f
001/00 () |
Field of
Search: |
;84/1.01,1.03,1.17,1.26,1.01-1.28 ;331/173-174 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Myers; Lewis H.
Assistant Examiner: Weldon; Ulysses
Claims
I claim:
1. In a musical instrument for playing a chord of a diatonic scale
upon activation of a control for producing the root tone of the
chord comprising:
a plurality of controls each for producing a different tone upon
activation thereof,
an equal plurality of leads on each of which may be applied
different tone signals of one octave of the diatonic scale, signals
of
a pair of buses each selectively connectable to a different
plurality of said leads,
means responsive to activation of each of said controls for
connecting one of said busses to that lead of its associated leads
on which appears the major third part of the chord of the root tone
selected by the activated control and for connecting the other of
said buses to that lead of its associated leads on which appears
the minor third part of the chord determined by the actuated
control,
means responsive to actuation of each of said controls for
generating control signals indicating which of said buses has the
major third part of said chord applied thereto,
an output circuit,
a selectively operable means having a first condition and a second
condition, and
means responsive to said control signals to couple to said output
circuit the one of said buses to which said major third part is
applied when said selectively operable means is in said first
condition and to couple to said output circuit the other of said
buses when said selectively operable means is in said second
condition.
2. The combination according to claim 1 wherein said selectively
operable means is normally in one of said conditions.
3. The combination according to claim 1 wherein said selectively
operable means comprises a player actuable touch bar biased to
maintain its first condition.
4. The combination according to claim 1 further comprising means
responsive to actuation of two of said controls to prevent
generation of said control signal.
5. For use with an electronic organ having a set of keys
corresponding to the notes of a musical scale, a chord organ device
comprising a plurality of leads at least equal in number to the
notes in an array of adjacent notes of the organ keyboard, means
responsive to actuation of any one of the keys corresponding to
said adjacent notes of the electronic organ to pass to a different
one of said leads for each such key the major third part of the
chord having as the root note the note selected by actuation of a
specific key and to pass to another and different lead for each
such key the minor third part of the chord selected by actuation of
said key, a pair of signal buses, means connecting said leads to
said buses such that a major third part of a chord appears on one
of said buses and a minor third part of a chord appears on another
of said busses for each note played, means for developing a control
signal indicating the bus on which said major third part is
developed, an output circuit, and gate means responsive to said
control signal for connecting said bus on which said major third
part appears to said output circuit.
6. The combination according to claim 5 further comprising a switch
having a stable and a second state, and wherein said means for
connecting includes means responsive to said switch in said stable
state.
7. The combination according to claim 6 comprising further means at
least responsive to said switch in said second position for
connecting the said output circuit and the bus having the minor
third part thereon.
8. The combination according to claim 5 further comprising means
for developing a pulsed voltage at a predeterminable tempo, said
gate means including means for effecting said connection only upon
receipt of each such pulse.
9. The combination according to claim 8 wherein said means for
developing includes means for varying the length of said pulse
voltage from a minimum duration pulse to a continuous voltage.
10. The combination according to claim 8 wherein said means for
developing comprises means for selecting a voltage continuously
variable between a maximum and a minimum value,
means upon actuation of a key to cause said voltage to rapidly rise
to said maximum level and thereafter decay to the selected
voltage,
said gate means connecting signals to said output circuit at an
amplitude determined by said voltage.
11. The combination according to claim 8 further comprising means
for disabling said means for developing upon concurrent actuation
of two keys in said octave.
12. The combination according to claim 5 further comprising means
responsive to actuation of three keys in said octave to disable
said attachment.
13. The combination according to claim 5 wherein said electronic
organ includes means for producing pedal and manual percussion
voices and wherein said attachment includes means for sounding
selected pedal percussion voices immediately upon actuation of one
of said keys.
14. The combination according to claim 5 wherein said attachment
includes a rhythm section, said rhythm section having a ramp
voltage generator for producing a voltage which varies as a saw
tooth function with time to provide a ramp portion increasing at a
prescribed rate from a minimum voltage to a maximum voltage and a
flyback portion which returns rapidly to the minimum voltage from
said maximum voltage,
means responsive at all times to actuation of any one of said keys
in said octave to immediately initiate a flyback of said ramp
voltage, and
means responsive to flyback of said voltage to sound said root
note.
15. The combination according to claim 14 wherein said ramp voltage
generator includes a capacitor,
means for maintaining said capacitor fully charged,
means responsive to actuation of a key for rapidly discharging said
capacitor,
means for recharging said capacitor at a prescribed rate while said
key is depressed and
means for rapidly charging said capacitor upon release of the
key.
16. The combination according to claim 14 comprising a second pair
of buses,
means responsive to actuation of any one of said keys in said one
octave to develop the root note of the selected key on one of said
buses and the fifth part of the chord of said root note on the
other of said buses,
means responsive to each flyback of said ramp voltage to
alternatively and repetitively connect said buses on which said
root and fifth note appear to said output circuit,
said means being responsive to said control voltage to initially
connect said bus on which said root note appears to said output
circuit.
17. The combination according to claim 16 wherein said output
circuit is the pedal circuit of said organ.
18. The combination according to claim 5 comprising a second pair
of novel buses,
means responsive to actuation of any one of said keys in said one
octave to develop the root note of the selected key on one of said
buses and the fifth part of the chord of said root note on the
other of said buses, and
means responsive to said control signal for connecting said bus on
which said root note appears to said output circuit.
19. In a system for controlling the rhythmic accompaniment provided
a player-controlled musical instrument,
a source of repetitive ramp voltage wave forms which vary between a
minimum and a maximum voltage level,
means for deriving a sequence of pulses in response to said ramp
voltage attaining preselected voltage levels of said repetitive
ramp wave forms,
means responsive to selected pulses for generating sounds of
diverse character,
a plurality of player-controlled means for selecting musical tones
to be played,
means normally maintaining said ramp voltage at a maximum
value,
means responsive to actuation of a single of said player-controlled
means to return said voltage to minimum value, and thereafter
repetitively produce said ramp voltage wave forms so long as said
player-controlled means is actuated, said means for deriving a
sequence of pulses producing a downbeat pulse upon said ramp
voltage returning to minimum value, and
means responsive to at least a first of said downbeat pulses to
sound the tone selected by said player-controlled means.
20. The combination according to claim 19 further comprising a
visual tempo indicator and means responsive to at least every other
downbeat pulse to actuate said visual indicator.
21. The combination according to claim 19 wherein said source of
ramp voltage source comprises a capacitor and wherein said means
responsive to actuation of a single of said player-controlled means
comprises,
means for maintaining said capacitor charged to said maximum
voltage, and
means for rapidly discharging said capacitor upon actuation of a
single player-controlled means.
22. The combination according to claim 21 further comprising means
responsive to concurrent actuation of at least two
player-controlled means for rendering inoperative said means for
discharging.
23. The combination according to claim 22 further comprising means
responsive to concurrent actuation of three of said player
controlled means for disabling said means responsive to selected
pulses for generating sounds.
24. The combination according to claim 19 wherein said sources of
ramp voltages comprises a capacitor and wherein said means
responsive to actuation of a single of said player-controlled means
comprises,
means for maintaining said capacitor charged to said maximum
voltage, and
means for disabling said means for maintaining and for concurrently
discharging said capacitor upon actuation of a single
player-controlled means.
25. The combination according to claim 19 wherein said source of
ramp voltage wave forms comprises,
a capacitor,
a constant current source for charging said capacitor,
means in series with said capacitor and said current source to
control the charging time of said capacitor,
switch means rendered conductive upon voltage across said capacitor
obtaining a preselected maximum value to discharge said capacitor
and rendered nonconductive upon the voltage across said capacitor
obtaining a preselected minimum value,
means responsive to flow of capacitor discharge current through
said switch means for terminating current flow through said
constant current source only so long as said switch means conducts
said discharge current, and
control means having a normal condition rendering said means
responsive to actuation of said switch means inoperative to
terminate current flow through said constant current source whereby
to maintain said capacitor fully charged.
26. The combination according to claim 25 wherein said means
responsive to actuation of a single control of said
player-controlled means comprises,
means for disabling said control means whereby said constant
current source is rendered nonconductive.
27. The combination according to claim 19 including a plurality of
pedal percussion voices,
means for selecting various of said voices to be sounded, and
means responsive to said downbeat pulse to sound said selected
pedal percussion voices.
28. The combination according to claim 27 further comprising means
for disabling said system upon actuation of three player-controlled
means for disabling said system
and means responsive to actuation of said means, for disabling for
preventing sounding of the pedal section of the organ.
29. The combination according to claim 27 including a plurality of
manual percussion voices,
means for selecting various of said manual percussion voices to be
sounded, and
means responsive to various beats of said sequence of pulses other
than said downbeat pulses to sound said selected manual percussion
voices.
30. The combination according to claim 19 further comprising means
for selectively disabling said means for normally maintaining said
maximum value of voltage whereby said source of repetitive ramp
voltages cycles automatically to produce repetitive ramp
voltages.
31. In a system for alternatively producing rhythmic accompaniment
provided a player-controlled musical instrument or independently
establishing said rhythm,
a ramp voltage generator comprising
capacitor,
means for charging said capacitor at a fixed rate,
discharge means responsive to the voltage across said capacitor
attaining a selectable maximum voltage to discharge said capacitor
to a minimum value,
control means normally operable to render said discharge means
inoperative to discharge said capacitor.
means responsive to actuation of a player controlled means for
rendering said control means ineffective so long as a
player-controlled means is actuated, and
switch means independent of said player-controlled means for
selectively rendering said control means ineffective.
32. The combination according to claim 31 including a plurality
of
selectable pedal percussion voices, and
means for sounding selected ones of said pedal voices at prescribed
intervals of discharge of said capacitor.
33. In a musical instrument for playing a chord of the diatonic
scale upon actuation of a control for producing the root tone of
the chord comprising,
a plurality of leads,
an equal plurality of two input OR gates,
a first pair of buses,
means connecting each of said OR gates between a different source
of a tone of the diatonic scale of a predetermined octave and one
of said buses,
means connecting each said lead to receive a gating voltage thereon
upon actuation of an organ control,
each of said lead being connected to an input of two different ones
of said OR gates such that upon generation of a gating voltage
thereon the major and minor third parts of the chord whose root
tone is selected by the organ control appear each on a different
one of said busses,
a second pair of buses,
each bus of said second pair of buses being connected to receive
gating voltage from a different plurality of said leads such that a
first of said second pair of buses receives said gating voltage
when a first of said first pair of buses receives said major third
part of said chord and a second of said second pair of buses
receives said gating voltage when a second of said first pair of
buses receives said major third part of said chord,
an output circuit, and
means responsive to said gating voltage on said second pair of
buses for selectively applying to said output circuit the major
third part of said chord.
34. The combination according to claim 19 wherein said organ has
pedal circuits including pedal generator means for producing pedal
frequencies, means for voicing frequencies generated in the organ
and pedal gate means for gating pedal frequencies to said means for
voicing frequencies,
said system comprising,
means responsive to actuation of a single player-controlled means
for preventing transmission of signals produced by said pedal
generator means through said pedal gate means.
35. The combination according to claim 34 further comprising
control means actuable in response to actuation of three of said
player-controlled means for disabling said system, and
means responsive to deactivation of said control means for
preventing transmission of signals produced by said pedal signal
generator means through said pedal gate means.
36. In an electronic organ,
a keyboard having a multioctave array of keys,
an array of tone generators, one tone associated with each of said
keys,
an electronic gate associated with each of said tone
generators,
a separate normally open key switch closable in response to
actuation of each of said keys,
means responsive to actuation of any one of an array of said keys,
and to consequent closure of a responsive key switch, for applying
ongating voltage to the electronic gates in series with only and
all of those of said tone generators representing one of a major
and minor chord corresponding musically with the actuated key for
all said octave of said keys.
37. The combination according to claim 36, wherein is included a
player operable control for applying in response to said actuation
said ongating voltage to the gates in series with those of said
tone generators representing only and all of the other of said
major and minor chord, said minor chord corresponding musically
with the actuated key for all of said array of keys.
38. The combination according to claim 37, wherein is further
provided means responsive to actuation of any three or more of said
keys for applying said ongating voltage only to gates corresponding
with said three or more of said keys.
39. In a rhythmic accompaniment system for an electronic organ,
a source of ramp signal having normally a predetermined level above
a reference value,
an array of keys on an organ keyboard,
means responsive to actuation of one of said keys for reducing said
ramp signal to said reference value substantially instantaneously,
and thereafter causing said ramp to slowly rise linearly to said
predetermined level, while said key remains actuated, and
means responsive to release of said one of said keys for causing
said ramp to rise substantially instantaneously to said
predetermined level,
means responsive to said reduction of said ramp signal to said
reference value for calling forth a first tone signal and
means responsive to attainment by said ramp signal of predetermined
levels for calling forth at least one further signal.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a chord organ attachment for
conventional electronic organs and an automatic rhythm system which
may be employed in conjunction with the chord system or
independently thereof.
Automatic chord attachments for conventional organs are known in
the prior art. In one such system, upon depression of a key in a
selected octave of the lower manual keyboard, the apparatus plays
the major or minor diatonic chord of the key depressed; the
specific key depressed determining whether the major or minor chord
is played. For instance, if the music is to be played in the key of
C, major chords result when a C, C sharp or F is played whereas a
minor chord is sounded when a D, D sharp or E is played. The
pattern repeats with major chords being sounded when F sharp, G and
B keys are played whereas minor chords are sounded when a G sharp,
A or A sharp is sounded. A touch bar switch is provided for
converting at will from the chord normally sounded upon actuation
of a given key to the other chord.
Chord organ attachments for conventional organs have validity
substantially only for use by a beginner or one who simply wishes
to pick out tunes and dress them up musically with chords. Such
attachments help particularly the student to learn the sounds of
the chords and also permit the student to produce pleasing musical
renditions even at a relatively low level of training. Thus it is
inconsistent with the level of knowledge of the student who would
normally employ a chord organ attachment to require to learn and
remember the major and minor diatonic chord progressions for each
of the musical keys in which the music may be written so that upon
depression of a given key he will know that the touch bar should be
depressed to convert from a major to a minor chord, when a major
chord would normally be sounded, or convert from a minor to a major
chord if a minor chord would normally be sounded.
In the aforesaid system, there is also provided a rhythm generator
for sounding the chords and various components thereof at a tempo
selected by the student and at one or several different rhythms.
The system does not, however, provide for sounding of percussive
instruments nor flexibility relative to the length of time the
various notes or chords are sounded either in the pedal or manual
octaves or permit continuous play of the notes with rhythmic
sounding of percussion instruments.
SUMMARY OF THE INVENTION
Briefly describing the main features of the present system, the
major chord is always played whenever a key is depressed and if it
is desired to play a minor chord a touch bar is depressed to
convert to minor chord sounding. There are two main beneficial
results flowing from such a system. Most beginner's music is
written in the major key and thus it is only occasionally that a
beginner will be required to operate the touch bar control. A
second feature is that the beginning student, even though somewhat
advanced beyond the student described immediately above does, not
have to memorize the diatonic chords in each of the various keys in
which music may be played. A student known that the major chord is
always played unless he presses the touch bar and, therefore, it is
only necessary to determine from the music whether the particular
chord is to be a major or minor chord.
The above result is accomplished by causing all four possible notes
of the chord, the root, fifth and major and minor third parts to
appear on separate uses. The major and minor third parts may appear
on one or the other of two buses assigned to these frequencies
depending upon the root note played. There are provided two gate
voltage buses which receive voltages alternatively in accordance
with which of the two third part buses has the major third part
applied thereto. Transistors sense the voltage bus on which the
gating voltage appears and blocks the amplifier to which the minor
third part is applied. When the touch bar is depressed the blocking
voltage is removed from the minor third part amplifier and applied
to the major third part amplifier.
Normally the chord attachment is operated to provide rhythmic
sounding of both the pedal and manual frequencies. This result is
accomplished by inserting gates in the circuits between the
frequency sources and the audio portion of the audio part of the
organ. In accordance with the present invention the gates are
opened rhythmically by pulses generated in response to actuation of
a key and at subsequent time intervals in the same measure various
voltage levels attained by a ramp voltage of a ramp function
generator. If continuous operation is to be effected in either or
both of the pedal and manual sections of the organ, continuous
paths are established through the pedal and manual systems while
the pulsing to the percussive instruments is maintained. Thus the
pulse generators are not disabled but continuous gating is
substituted in the pedal and manual sections for the pulsed gating
during automatic rhythm operation.
The system of the present invention provides five basic rhythms
which employ pedal toes alternating between the root and fifth
notes. It is necessary to provide information which allows the root
to be sounded first on closure of a key switch and thereafter to
alternate with the fifth part of a chord. A root fifth flip-flop is
employed for this purpose with the aforesaid gating voltage buses
being employed to establish the flip-flop initially to pass the
root frequency on the first downbeat after closure of the key
switch.
A single-multiple note detector is found in the prior art to the
extent that when a note is played the ramp function generator is
placed into operation and when two notes are played the ramp
function generator is disabled. In accordance with the present
invention if three notes are played the organ reverts to its normal
mode of operation. The student can utilize this feature to teach
himself the sound of the various chords and the note content
thereof. Thus the student can depress a key and hear an entire
chord played. He may now select three keys to depress and determine
if the chord thus played has the same sound as the chord
automatically played by the attachment. In this way the student
learns the sounds of the chords and the note content thereof.
Another feature of the invention is that a downbeat is sounded
whenever a key is actuated. A fast charge circuit is incorporated
in the ramp voltage generator such that whenever a key is released
the ramp voltage capacitor is rapidly charged to maximum voltage.
Thus as soon as another key is depressed, a downbeat signal is
produced by the ramp voltage generator.
As indicated above, rhythm percussion effects are provided by means
of percussion trigger gates which sense various conditions on the
ramp voltage of the ramp function generator. The circuits are such
that base percussive voices are triggered simultaneously with bass
notes (root or fifth) and other percussive voices are sounded
concurrently with the chords. In the automatic chord type of
operation, the percussive sounds are triggered by actuation of a
key switch whereas in the automatic rhythm operation the percussive
sounds are sounded repetitively irrespective of and independently
of operation of a key switch. In this mode of operation the organ
keyboard reverts to its normal mode of operation.
The ramp function generator is novel in its simplicity. The
generator employs a constant current source for charging a
capacitor at a rate determined by the value of a variable resistor.
Thus, the tempo of the system may be altered by varying the value
of the resistor. Measures from one half second to three seconds are
attainable with the circuit described herein but obviously may be
made larger or smaller by changing the range of the value of the
variable resistor or potentiometer. A transistor switch is employed
to sense when the voltage across the capacitor has attained a
preselected maximum and to discharge the capacitor. By concurrently
shutting off the constant current source the capacitor may be
discharged rapidly.
The voltage at which the switch operates to discharge the capacitor
has a prescribed value for the waltz and is half that value for all
other rhythms in accordance with the present invention. Since the
rate of charge of the capacitor is fixed by the constant current
source, by reducing the voltage at which said switch operates to
one-half that of the waltz, two ramp voltage functions are
generated within one waltz measure. Thus, when switching from waltz
to other rhythms the measure is not changed but the ramp voltage
functions per measure are doubled. Transistor switches are employed
to sense when the ramp voltage has attained specific percentages of
its maximum voltage and to generate beats when each such precise
percentage is achieved. Two such levels are established for
instance so that in the waltz function there are three events
sensed per measure, downbeat and two further pulses, whereas in all
other rhythms up to six beats are provided which may be selectively
employed or eliminated in accordance with the particular rhythm
function to be generated. The various transistor switches are
permanently wired to certain of the gates of the chord organ
attachment but are selectively connected to various of the other
gates in accordance with the particular rhythm to be played.
One other feature of the invention relates to the fact that
whenever a key is depressed, whether properly timed with the prior
notes or not, a downbeat is sounded. This feature is achieved by
causing the ramp voltage to commence anew each time a key switch is
actuated and sensing this event to pulse a downbeat light, sound
the bass percussion instruments selected and play the sent note
through the pedal section of the organ.
Additional features of the invention relate to eliminating
undesirable effects which may be generated at times of switch over
from chord to normal play and at times of improper operation of the
chord attachment.
It is accordingly a broad object of the present invention to
provide a chord organ which always plays the major chord of each
tonic note played.
It is another object of the present invention to provide a chord
organ attachment for electronic organs in which a major chord is
always sounded for each root note played and which provides a touch
bar mechanism for converting to a minor chord.
Yet another object of the present invention is to provide a chord
organ and automatic rhythm attachment for electronic organs in
which pedal percussive voices may be sounded on at least each
downbeat and the accompaniment percussive voices may be sounded on
at least each second beat of each measure.
It is another object of the present invention to provide a chord
organ attachment for an electronic organ, which attachment has an
automatic rhythm system which may be employed with the chord organ
attachment or independently thereof, and in the former case is key
switch actuated and in the latter case is operated
continuously.
It is yet another object of the present invention to provide a
chord organ attachment for electronic organs, which has an
automatic rhythm system component and wherein the chords may be
played as rhythmic chords or continuous chords without affecting
the operation of automatic percussive voices under control of the
automatic rhythm system of the attachment.
It is another object of the present invention to provide an
automatic rhythm and chord system attachment for electronic organs
in which the root and fifth parts of the chord are voiced in
alternation through the pedal section of the organ and the chords
are played through the lower manual section of the organ and in
which either one or both of the pedal and lower manual notes may be
sounded rhythmically or continuously.
It is another object of the present invention to provide a chord
and rhythm attachment for an electronic organ wherein when chord
operation is employed the rhythm section is operated in synchronism
with key operation and wherein when only the rhythm section is to
be employed, rhythm operation is independent of key actuation.
Still another object of the present invention is to provide an
automatic chord attachment for electronic organs in which when
three keys are played in the lower manual octave selected for chord
operation the organ reverts to normal operation and the attachment
is rendered inoperative.
It is yet another object of the present invention to provide a
chord organ attachment for electronic organs which sounds a
downbeat whenever a single note in a predetermined octave of the
organ is sounded.
It is another object of the present invention to provide various
secondary functions in a chord and rhythm attachment for
conventional organs which prevent undesirable sounds being
generated upon switching between chord and normal operation on the
one hand and normal and chord operation on the other hand.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and still further objects, features and advantages of the
present invention will become apparent upon consideration of the
following detailed description of specific embodiments thereof,
especially when taken in conjunction with the accompanying
drawings, wherein:
FIGS. 1, 4 and 6-8 taken together provide a schematic wiring
diagram of preferred embodiment of the present invention;
FIGS. 2 and 3 illustrate the wave forms occurring in the ramp
function generator of the present invention; and
FIG. 5 is a schematic block diagram illustrating the major
interconnections between the chord organ and rhythm attachment of
the present invention and a conventional organ.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now specifically to FIG. 1 of the accompanying drawings
there is illustrated among other things a ramp generator 1 employed
to provide automatic rhythm to the rhythm system forming a part of
the apparatus of the invention.
The ramp generator employs a charging capacitor 2 selectively
charged through a transistor 6 of a constant current source
comprising a source of voltage appearing on a bus 4, the
NPN-transistor 6 and transistors 16 and 24. Current through
transistor 6 is supplied to a bus 8 connected to the upper end of
the charging capacitor 2 as viewed in FIg. 1. The lower end of the
capacitor 2 is connected to ground via fixed resistor 10 and a
variable resistor 12.
The junction of the charging capacitor 2 and the resistor 10 is
connected via a further resistor to base electrode 14 of the
transistor 16 having a grounded emitter 18 and having its collector
20 connected to a base electrode 22 of transistor 24. The collector
of the NPN-transistor 24 is connected directly to ground while its
emitter is connected to the base electrode of transistor 6 and to
the high-voltage bus 4 through resistor 26.
The bus 8 is connected through a diode 28 to the emitter electrode
of a PNP-transistor 30. Collector electrode of the transistor 30 is
connected to the ground through a resistor 32. The base electrode
of the transistor 30 is connected through a resistor to collector
electrode 34 of an NPN-transistor 36 having its emitter 38
connected to the junction of the capacitor 2 and the resistor 10.
The base electrode 14 of the transistor 16 is connected via
collector-emitter circuit of an NPN-transistor 40 to ground.
Describing now the operation of the circuit thus far described;
during periods when the ramp generator is to be maintained
inoperative, a voltage is applied to base electrode 42 of the
transistor 40 placing the transistor 40 in saturation. Saturation
of the transistor 40 substantially grounds the base 14 of the
transistor 16 maintaining this transistor in a nonconducting
condition, thereby also maintaining the transistor 24 in the
nonconducting condition. The voltage of bus 4 is thus applied to
the base of the transistor 6 rendering it highly conductive so that
capacitor 2 is charged fully at a rapid rate through the resistor
13 and transistor 40. The bus 8, assuming a voltage of about 16
volts on the bus 4, is maintained at about 12 volts so that the
transistors 30 and 36 are conductive due to the bias maintained on
the base electrode of the transistor 30 via a voltage divider
including resistor 44 to a bus 46 and resistors 48, 50 and 52 to
ground.
If now the voltage is removed from the base of the transistor 40,
transistor 40 becomes nonconductive, releasing the base 14 of the
transistor 16 and a positive potential appears at the base 14 due
to current flow through the transistors 30, 36 and resistors 10 and
12. Conduction of the transistor 16 places the transistor 24 into
conduction and the transistor 6 is shut off. The capacitor 2 is
short circuited through the transistors 30 and 36 which are now
saturated. The capacitor discharges until the forward bias across
diode 28 is lost at about 11/2 volts providing the fly back
interval in a conventional ramp generator; that is, saw tooth
generator. Rapid discharge results from the low resistance of the
discharge circuit and the termination of charging current through
the transistor 6.
The voltage on the bus 8 falls until it reaches a shut off
potential for the diode 28 occurring at approximately 11/2 volts.
At this time the transistors 30 and 36 become nonconductive. The
voltage now appearing at the base 14 of the transistor 16 is such
as to render it partially conductive. The transistor 24 is rendered
partially conductive rendering the transistor 6 conductive to an
extent determined by the setting of the potentiometer 12.
The constant current through the transistor 6 again charges the
capacitor, the adjustment of the slider 12 determining division of
the charging current between the resistors 10 and 12 and the base
of the transistor 14. The feedback voltage of the transistor 6 is
thus determined and in consequence its level of conduction is
regulated to charge the capacitor at a fixed rate. The voltage
rises linearly due to the constant current operation of the
transistors 6, 16 and 24 until it reaches a value equal to two
diode drops greater than the voltage on the bus 46. At this time
the transistor 30 and thus the transistor 36 are both placed in
conduction and the capacitor 2 is again discharged. This operation
continues so long as the base of the transistor 40 has a low
potential thereon, that is, is substantially grounded. When the
base of transistor 40 is again permitted to go positive relative to
the emitter of the transistor 40, the transistor 40 saturates and
the ramp function is discontinued.
Incorporated in the ramp function generator are two transistor
switches which are driven into saturation in sequence in response
to different levels of the ramp voltage. The switching on of each
of these switches produces pulses providing the basic organ rhythm
in conjunction with the pulse produced upon falling of the bus 8
upon discharge of the capacitor 2. Thus, three timing pulses are
produced permitting the desired rhythms to be generated.
Referring again specifically to FIG. 1, the two transistor switches
are generally designated by the reference numerals 54 and 56 which
are identical in operation. The switch 54 comprises an
NPN-transistor and a second NPN-transistor 60. Their emitters are
connected together and through a resistor 62 to ground. The
transistor 58 has its collector connected directly to the bus 4
while the transistor 60 has its collector connected through a
resistor 64 to the bus 4. The base of the transistor 58 is
connected through a resistor to the junction of the resistors 50
and 52 while the base of the transistor 60 is connected through a
resistor 66 and diodes 68, in series, to the bus 8.
At a voltage determined primarily by the relative values of the
resistors 48, 50 and 52 (in parallel with additional resistors 76,
78, 80 and 82) the transistor 60 which is normally nonconductive is
placed in conduction upon the voltage on the bus 8 achieving a
value equal to two diode voltage drops (diodes 68) greater than the
voltage at the junction of resistors 50 and 52. When the voltage on
the bus 8 does exceed the voltage at the junction of the resistors
50 and 52. By the prescribed amount, the transistor 60 is placed in
conduction very rapidly due to positive feedback through resistor
70 to transistor 58 and the effect of the common connection to
ground through resistor 62. The sudden drop in potential at the
collector of transistor 60 provides a second pulse of the desired
rhythm.
The switch 56 as stated above is identical with the switch 54,
employed left and right transistors 55 and 57 as viewed in FIG. 1,
but the switching voltage is determined by the voltage at the
junction of the resistors 48 and 50 and thus is at a higher voltage
than the voltage at which the switch 54 operates.
Reference is made to FIG. 2 of the accompanying drawings which
illustrates the ramp function of b 2rhythm generator in the waltz
mode of operation. The specific mechanisms for responding to the
various pulses are not discussed at this point but simply the
operation of the rhythm system. During waltz mode operation, the
resistors 48, 50, 52 et al. determine the precise voltages in which
the switches 54 and 56 fire and these voltages are selected
respectively at one third (V.sub.2) and two thirds (V.sub.1) of the
maximum ramp voltage amplitude designated in the diagram as
V.sub.3, which appears on lead 46. The ramp voltage, starting from
its lowest value on the bus 8, rises until it equals two diode
drops greater than the voltage at the junction of the resistors 50
and 52. At this point the switch 54 operates and the voltage on the
collector of the transistor 60 falls quickly to produce a negative
spike. At a voltage on bus 8 equal to two diode drops greater than
the voltage V.sub.1, the switch 56 is triggered so that a negative
pulse is produced at the collector of the transistor 55.
Subsequently the voltage of the bus 8 rises to a value 2 diode
drops greater than V.sub.3 to trigger transistors 30 and 36 and
produce discharge of the capacitor 2 thus terminating the sawtooth
wave.
In the waltz mode of operation each ramp function is employed as a
single measure of music because the rhythm for such music is fixed
at three beats to the measure. The reason for this is apparent. In
other forms of music, however, for instance swing, fox trot, rock
& roll and Latin, a minimum of four and as many as six beats
are required per measure. Thus the present invention must provide a
means for changing the beats per measure when changing from the
waltz mode of operation to any other mode.
Referring again to FIG. 1, when the system with which the rhythm
generator is employed is in any rhythm mode other than waltz,
terminals 72 and 74 are shorted placing resistors 76 and 78 in
parallel with the series resistors 48 and 50 and placing resistor
82 in parallel with all of the resistors 48, 50, 76, 78, 52 and 80.
As a result of the change in the resistance divider network between
the bus and ground, the voltage V.sub.3 which produces triggering
of the transistors 30 and 36 and therefore discharges the capacitor
is made equal to one-half of the voltage (see FIG. 3) at which
triggering occurs for the waltz rhythms illustrated in FIG. 2. Also
the V.sub.2 and V.sub.3 voltages occur at one-half and
three-fourths of V.sub.3, respectively. Since the charging time of
the capacitor 2 is linear and the amplitude at which the capacitor
is discharged is one half of the amplitude in the waltz time,
precisely two ramp voltages are produced within the same length of
time as a single ramp voltage is produced for the waltz. Thus the
measure length, or specifically, the tempo, does not change when
switching from waltz to any of the other rhythms but the available
rhythm content of the measure is materially altered.
As will be indicated subsequently, the voltage on the base of the
transistor 42 is under control of the notes in the appropriate
octave of the lower manual with which the chord organ is
associated. Specifically, when a key is not played the transistor
40 is saturated but when a key is depressed the transistor 40 is
turned off and maintained off so long as the key is depressed.
Referring now specifically to FIG. 4 of the accompanying drawings,
there is illustrated the key circuits for affecting the various
gating functions required to connect to the chord circuits of the
present invention the various frequency sources of the organ
required to produce the key selected chord. The circuits are
associated with a separate contact on each of the keys of a
specific octave of the lower manual of the main chord. These
contacts, which are generally designated by the reference numeral
100 in FIG. 4, have adjacent thereto in the drawing, an indication
of the root note of the chord to be produced by depression of each
key. A voltage is normally developed on a bus 102 connected in
common to the stationary contact in each of the keys 100 while
movable contacts of each of these keys is connected to a distinct
bus 104, 106, 108, etc.
The bus 104, for instance, is connected through a resistance 110 to
a junction point 112. Junction point 112 is connected through a
resistor 114 to a bus 116 on which the minor third part of the
chord is to appear, alternatively the minor third or the major
third depending upon which of the root keys 100 is depressed. The
junction point 112 is connected through a diode 118 to a D sharp
frequency source 120. The junction point 112 is also connected
through a resistor 122 to a bus 124 connected through the B key 100
to the bus 102.
The lead 104 is also connected through a resistor 126 to a junction
point 128. The junction 128 is connected through a resistor 130 to
a bus 132 on which appears major or minor third parts of a chord
depending again on which of the keys 100 is depressed. The junction
point 128 is further connected through a diode 134 to frequency
source 136 for the note E for the particular octave under
consideration. The junction point 128 is also connected through a
resistor 138 to the bus 106 which is connected through the C sharp
key to the bus 102.
Continuing with the description of the circuitry associated with
the key 100, the bus 104 is connected through a resistor 140 to
ground and through a resistor 142 to a bus 144. A voltage appears
on the bus 144 or a corresponding bus 161 depending upon which of
the keys 100 is depressed and serves to provide an indication to
the chord system as to which of the notes appearing on the leads
154 and 156 is the root and which is the fifth part of the chord
and to which of the notes appearing heads 116 and 132 is the major
or minor third part of the chord. The lead 104 is connected in a
manner identical with the connections to the sources 120 and 136 to
additional frequency sources 146 and 148. The source 146 is the C
note source for the particular octave under consideration while the
source 148 is the G note source for the same octave.
Whenever a key 100 is closed, for instance the key C, a high
voltage is applied to the lead 104 which forwardly biases the
diodes 134 and 118 related to major and minor sources 136 and 120,
respectively, and corresponding diodes 150 and 152 related to the
root-fifth sources 146 and 148, respectively. In consequence,
communication is established between the sources 120 and 136 and
the buses 116 and 132 respectively and the sources 146 and 148 and
buses 154 and 156 respectively. The buses 154 and 156 are
root-fifth buses to which the sources 146 and 148 are gated. If a C
note is played the root frequency appears on bus 154 and the fifth
part frequency appears on bus 156. Their functions may be reversed
if some other key is played. For instance, if the note G is played,
the G note is the root whereas when a C is played the G note is the
fifth part of the chord and the functions of buses 154 and 156 are
reversed.
It should be noted that although the frequency sources in the upper
row of the FIG. 4 are designated at times by different reference
numerals from the signal source in the lower row, these sources
where they are designated by the same note are the same source. For
instance, the source for the note G in the upper row of sources is
the same sources as that designated by the reference numeral 148 in
the lower row of sources.
The composite of the various sources, keys, diodes, etc., provide
an octave of square wave frequencies from the main organ and these
frequencies are applied to a set of 24 diode gates. Whenever one of
the keys 100 is closed, a positive voltage is applied to a group of
4 of the gates; in the case of the note C, these being the gates
including the diodes 118, 134, 150 and 152, respectively. The
application of high voltage to the gates opens the gates and
permits the frequencies with which the gates are associated to play
through to their respective buses and subsequently, as will be
indicated later in the specification, to various transistor rates
and amplifiers in the main body of the chord system.
As previously indicated, a primary object of the present invention
is to provide major/minor chord logic such that a beginning student
may readily select a major or minor chord without a high degree of
knowledge of the chords or more specifically without having to
learn and remember the major and minor chord progressions and the
musical key in which the music is written in order to make such a
major to minor chord transformation. In accordance with the present
invention the system is programmed to always play a major chord. A
touch bar is provided adjacent the 12 keys of the selected lower
manual such that if a student wishes a minor chord he merely
depresses the bar and a minor chord is automatically played
regardless of the root frequency of the chord.
Referring now specifically to FIG. 6 of the accompanying drawings,
the circuits necessary for such a selection are illustrated. Assume
for purposes of illustration that a C chord is to be played and
initially the student does not depress the touch bar so that a C
major chord is played. Upon depression of the C note in FIG. 4,
high voltage appears on the bus 144 and is applied to the base of a
transistor 160 having a grounded emitter and a collector DC coupled
to a stationary contact 162 of a touch bar switch 164. When the
touch bar is not depressed the contact 162 is contacted by movable
contact 166 of the touch bar switch 164 and connected via a lead
168 to the base of a transistor 170. Upon application of high
voltage to the base of the transistor 160 the voltage at its
collector falls and the transistor 170 is turned off so that the
voltage at the base of a transistor 172, connected to the collector
of the transistor 170, rises. The transistor 172 goes into
conduction and reduces the voltage at the collector of a transistor
174, the collectors of the transistors 172 and 174 being connected
together. Thus the collector of transistor 174 is shorted to ground
and rendered inoperable. The base of the transistor 174 is
connected to the lead 116 and thus when a C note is played it
carries the D sharp note, the minor third part of the chord.
It should be noted that a transistor 176 has its collector
connected to the collector of the transistor 170 so that when the
transistor 170 is turned off, as in the above example, high voltage
is applied to the collector of the transistor 176 and rendered
capable of conduction. The base of the transistor 176 is connected
to the major third part, bus 132 of the key selection matrix, and
therefore the major third part of the chord is played through and
appears on a lead 178 connected to the collector of the transistor
176. The bus 178 is connected through a diode-resistor gate 179 to
a further lead 180. If positive voltage is applied to the junction
of the diode and resistor forming gate 179, signals can pass.
If the touch bar is depressed, its movable contact 166 is connected
to a minor chord terminal designated by the reference numeral 182.
The minor chord terminal is connected to the collector of a
transistor 184 having its base connected to the lead 161. In the
example given, the lead 161 is not energized since none of the keys
with which this bus is associated have been depressed. In
consequence, the voltage appearing at the collector of the
transistor 184 is high and the transistor 170 is turned on. High
voltage is removed from the collector of transistor 176 and thus
the note E, the note on the bus 132, is blocked. The transistor 172
however has a low voltage applied to its base and therefore it is
turned off and a high voltage appears at the collector of the
transistor 174. The transistor 174 therefore plays through and the
D- note, appearing on the bus 116, is transmitted via a bus 186,
and thence through a diode-resistor gate 187 to a further bus
188.
Thus, by actuation of the touch bar switch 164, the student is able
to shift from the major to the minor chord of the C chord.
The other situation which may exist relative to major-minor chord
selection is when a note is played relative to which a voltage
appears on the lead 161 rather than on the lead 144. This occurs
for instance, when the root frequency is the note G rather than the
note C. When the note G is depressed, a voltage appears on the lead
161 and the transistor 184 is placed in conduction while the
transistor 160 remains nonconductive. Also when the note G is
played the frequency of the major third part B appears on the lead
116 whereas the minor third part appears on the lead 132. Thus the
major and minor third part's positions on the leads 116 and 132 are
reversed relative to the situation when the root frequency is the
note C. The note B, the major third part, is applied to the base of
the transistor 174. Since, the transistor 160 is nonconductive, the
transistor 174 is conductive and the note B, the major third part,
plays through. If now the touch bar is depressed, the transistor
170 is rendered nonconductive. The transistor 174 is also rendered
nonconductive blocking the major third part of the chord and the
transistor 176 is rendered conductive and plays through the minor
third part of the chord, that is the note A-.
It is apparent that the transistors 160 and 184 carry the
information relative to the base and fifth notes and in consequence
may be employed to select the appropriate transistor 174 or 176 to
gate through the major or minor third part of the chord as
desired.
The information available at the transistors 160 and 184 also
indicates which of the frequencies available on the leads 154 and
156 is the root frequency and which is the fifth part of the chord,
this information being essential relative to certain of the rhythms
provided in the organ. For instance, and reference again is made to
FIG. 2, the sequence of notes played for a waltz at the various
intervals during the measure are the root, chord, chord in the
first measure and fifth, chord, chord in the second measure. The
root and fifth frequencies are played alternately on the downbeats
and the full chord is played on each of the second and third beats.
In rock music, see FIG. 3, the root frequency is played on the
downbeat, a chord is played at the 1/4 and 3/4 measures, the third
beat (3/8 measure) is suppressed, and the fifth part of the chord
is played at one-half and seven-eighths measure (fourth, sixth
beats). The various rhythms available in the apparatus of the
invention are tabulated below in table I. In table I it will be
noted that the waltz, and this of course has been discussed
relative to FIG. 2, contains three beats per measure providing the
three-fourths time. All of the other rhythms are based on two ramp
voltages per measure and are based on six beats per measure. These
six beats are not used in all rhythms. In table I below the six
possible beats are indicated immediately above the row for waltz by
the numbers 1-2-3 and repeating 1-2-3 horizontally across the page.
For the Fox Trot, only four beats are employed, the first and
second beats of each of the two ramp voltages per measure with the
third beat of each ramp voltage being suppressed. Swing employs the
same basic rhythm as the fox trot but in addition the root and
fifth notes are played through the pedal channel at the second and
fourth beats. ##SPC1##
The time relationship between the pulses are as follows:
Waltz (1)-2 8 units) 2-3 8 units) 1 measure 3-1 8 units) All Other
1-2 6 units) Rhythms 2-3 3 units) 3-1 3 units)
It is apparent from the table that it is essential to proper
operation of the organ that the circuitry provide signals
indicating the buses on which the various parts of the chord appear
for each chord played.
Referring again to FIG. 6, the aforesaid information is available
from a flip-flop generally designated by the reference numeral 190.
The flip-flop is conventional in configuration and employs a
transistor 192 and a second transistor 194. The base of the
transistor 192 is connected via a lead 196 and AC coupling
capacitor 198 to the collector of the transistor 184. Similarly the
base of the transistor 194 is AC coupled through a capacitor 200 to
the collector of the transistor 160.
Upon depression, for instance of the key C, high voltage applied to
the bus 144 triggers the transistor 160 so that its collector falls
and a negative pulse is applied through the capacitor 200 to the
base of the transistor 194. The transistor 194 is turned off and
the transistor 192 is turned on due to the cross coupling between
the collectors and bases of the two transistors. This is apparent
from the drawings. If, on the other hand, the root frequency is G,
high voltage appears on the lead 161, the transistor 184 is turned
on and the transistor 192 is forced into a nonconductive condition
while the transistor 194 is turned on. Thus, the flip-flop 190 is
set with transistor 192 conductive if the control voltage appears
on the lead 44 and with the transistor 194 conductive if the
control voltage appears on the lead 161.
The transistors 192 and 194 have their collectors connected via
leads 202 and 204 respectively to the collector circuits of
transistors 206 and 208 respectively. The base of the transistor
206 is connected to the bus 156 and the base of the transistor 208
is connected to the lead 154. Thus, when the note C is played, the
transistor 208 has the root frequency applied to its base and the
transistor 206 has the fifth part of the chord applied to its base,
this being the note G. However, if the note G is the root note, the
transistor 206 has the root frequency applied thereto and the
transistor 208 has the fifth part of the chord, the note D, applied
thereto. If now the note C is played and high voltage appears on
the lead 144, thereby turning the transistor 194 off. The voltage
on the lead 204 connected to the collector of the transistor 194
via resistor 203 and diode 205 is high and high voltage is applied
to the collector of the transistor 208 so that the transistor 208
plays through the root frequency. The transistor 206 however has a
low voltage applied thereto due to the conduction of the transistor
192 of flip-flop 190 and the fifth part of the chord does not play
through at least initially when the key is first depressed.
Subsequent events cause the flip-flop to switch back and forth so
as to select the root and fifth part of the chord as required to
provide the rhythm desired by the system.
The signals on the collectors of the transistors 206 and 208 are
applied via diode-resistor rates 209 and 211, respectively, to
buses 210 and 212 respectively. It will be noted in FIG. 6 that the
four buses or leads 180, 188, 210 and 212 are connected together to
the base of a chord amplifier, generally designated by the
reference numeral 215 and from the collector of the chord amplifier
are connected via lead 213 to a terminal 216, FIG. 7, which applies
the signals to the accompaniment manual filters 218 illustrated in
FIG. 5. The accompaniment manual filters are a part of the standard
organ.
As will be explained subsequently the diode-resistor gates 179,
187, 209 and 211 are pulsed on the second beat and at times (waltz,
Latin) the third beat of each measure or half measure to permit
passage of the chord frequencies to the chord amplifier and
subsequently to the organ manual filters.
Whenever transistors 206 or 208 are operative signals are also 2 to
the base of a transistor 215 having its collector connected to a
terminal 217 of FIGS. 5 and 6. The terminal 217 in FIG. 6 connects
the root and fifth frequencies to a pedal divider 216 (see FIG. 5)
located in the organ on the accessory board. The pedal divider 216
divides the frequency supplied thereto by a factor of 2 thus
providing a pedal frequency corresponding to the root note. In the
examples given above the notes would be the note C or the note G at
the pedal frequencies. As will be explained subsequently, the pedal
notes are pulsed by application of pulses to a pedal diode gate
240, FIG. 5, via a terminal 310. The terminal 310 has pulses
applied thereto from base trigger transistor 282 of FIG. 8. The
transistor 282 is always triggered on downbeat and selectively
triggered on the second or third beat depending upon the rhythm
selected.
In accordance with the present invention the pedal root frequency
may be sounded continuously at the discretion of the player. This
selection is effected by a switch 220 which when closed applies a
positive voltage via lead 221 and diode 240 to the base of a
transistor 222 having its collector connected to the base of the
transistor 215. When the switch 220 is closed the transistor 222 is
saturated and clamps the base of the transistor 215 to ground
thereby blocking transmission of signal therethrough. The voltage
applied to the base of the transistor 222 via the lead 221 is also
supplied via leads 221 and 224 to resistors 226 and 228. The
resistor 226 is connected to the junction of diodes 227 and 230,
the diode 227 being connected to the collector of the transistor
206 and the diode 230 being connected to the collector of
transistor 160. The resistor 228 is connected to the junction of
two diodes 232 and 234; the diode 232 being connected to the
collector of transistor 208 and the diode 234 being connected to
the collector of transistor 184.
Taking now the example above where the note C has been played and
the switch 220 is closed, a positive voltage is supplied to the
base of the transistor 160. Its collector is clamped at about
ground potential and the junction of the diodes 227 and 230 is held
just slightly above ground so that the diode 227 is reverse biased
and cannot pass signals. On the other hand the transistor 184 is
not conducting, diode 234 is reverse biased and therefore the
junction of the diodes 232 and 234 is at a voltage determined by
the lead 224 and signals may be transmitted through the diode 232.
As previously indicated the root note when C is played appears on
the lead 154 and therefore at the base of the transistor 208. Thus
the root note may be transmitted through the diode 232 and resistor
236 to the base of a transistor 238. The terminal 217 is connected
in the collector circuit of transistor 238 and therefore the root
note C is applied to the terminal 217 in FIG. 5 and subsequently to
the pedal divider 216. The fifth part of the chord is blocked out
of the pedal circuit by grounding of the junction of diodes 227 and
230 in the above example.
It is apparent that so long as the switch 220 is closed the
condition set forth above subsists and so long as the ramp
generator is operating (i.e., a key is depressed) a continuous
pedal signal is supplied to the pedal divider and subsequently to
the speakers of the organ.
The switch 220 when closed connects high voltage lead 219 to a
terminal 239 in FIGS. 5 and 6. The terminal 239 thus receives a
continuous voltage and maintains the pedal diode gate 204 open so
that the pedal note sounds continuously.
It will be noted that the transistors 174 and 176 are unaffected by
the above so that the third part of the chord is played
conventionally. Also although the fifth part of the chord is
blocked out of the pedal circuit due to the grounding of the
junction of the diodes 227 and 230, the fifth part and also the
root part of the chord still play through to the accompaniment
manual via the chord amplifier 214. Specifically, a further lead
242 applies a gating voltage, derived from a lead 290 via diode
298, via a resistor 244 and diode 246 to the collector of the
transistor 206 and resistor 243 and diode 245 to the collector of
transistor 208. The fifth part of the chord then modulates the
junction of the resistor 244 and diode 246 and the root frequency
modulates the junction of diode 245, resistor 243 so that these
modulating frequencies are applied to the base of the chord
amplifier 214. Thus, the root, third and fifth parts of the chord
appear at the chord amplifier 214 and are played through the
accompaniment manual while only the root part of the chord is
played through the pedal as a sustained note.
The pulsing of the signals applied to the transistor 214 to
introduce rhythm into the accompaniment manual section is now
described. Referring now specifically to FIGS. 7 and 8 of the
accompanying drawings, the circuits for effecting rhythmic
servicing of the lower manual and pedal frequencies is illustrated.
The operation of the system relative to a waltz is initially
described. In this configuration ON-OFF switch 244 is in the ON
position so that contact 246 is connected to contact 247 and
contact 250 is connected to contact 252. All other push buttons are
up except the waltz push button which has contact 254 connected to
contact 256, has contact 258 disconnected from contact 260 and has
contact 262 connected to contact 264. The contact 258 is connected
to the terminal 72 in FIG. 1 and the terminal 260 is connected to
the terminal 74 also in FIG. 1. The terminal 254 is connected to
terminal 65 (collector of transistor 55) of FIG. 1. The terminal
256 is connected to terminal E and through various resistors and
capacitors and a matrix diode 265 to a base electrode 268 of a
chord gate transistor 266 of FIG. 8. Terminal 262 is connected to
terminal L of FIG. 8 which is connected through a coupling
capacitor to a base of a transistor 272, the downbeat light gating
transistor; the light being designated by the reference numeral
274. The terminal 264 of the waltz switch is permanently connected
to a terminal M of FIG. 6 connected through a resistor 278 to the
collector of a transistor 280. Thus when the waltz switch is
depressed the contacts 254 and 256 are shorted and the voltage
appearing at the collector of the transistor 55 of the ramp
generator is connected to the base of the chord gate transistor
266. Also the L and M terminals are connected together so that the
tempo light is driven from the collector of the transistor 280.
Assuming that a key is depressed, the voltage on the lead or bus 8
suddenly falls and a pulse is directed via the bus 8, coupling
capacitor 284 and matrix diode 285 to the base electrode of base
trigger transistor 282, turning this PNP-transistor on temporarily
due to the capacitive coupling of the bus 8 to the transistor 282
through the capacitor 284. When transistor 282 fires on downbeat, a
pulse is coupled through capacitor 286 to a terminal 288 which is
connected to drive a selected member of the rhythm percussion board
of the main organ. Specifically, the player may select bass, drums,
cymbals, or other bass percussive instruments. The pulse appearing
at the terminal 288 actuates the gates necessary to permit sounding
of the fundamental and the harmonics representative of these
various voices.
Pulsing of the amplifier 282 also pulses a terminal 310 of FIGS. 5
and 7 via diode 306 of FIG. 8. The pulse on terminal 310 passes the
root frequency on the first and alternate downbeats through the
pedal circuit via pedal divider 216 and pedal diode gate 240. On
the second and alternate downbeats the fifth part of the chord is
gated through the pedal diode gate 240. Thus on each downbeat the
bass percussion voices are sounded and the root and fifth parts of
the chord are sounded in alternation.
Continuing, the voltage on the ramp generator now begins to rise
and reaches a level established at transistor 60 so that the
transistor 60 now fires and the voltage on its collector falls.
This voltage which appears on bus 288 is capacitively coupled to
the base of the transistor 280 and via matrix diode 289 to the base
of the transistor 266.
As previously indicated, the waltz rhythm is root, chord,
chord-fifth, chord, chord. The pulse at the base of the transistor
266 produces a positive pulse on a lead 289 which is applied to the
base of a transistor 292. The transistor 292 triggers an
accompaniment rhythm percussion board of the main organ to provide
sounds such as snare drums, brush, block, etc. on each second beat
of each waltz measure. The collector of the transistor 266 is also
connected through a diode 294 to the junction of a sustain
capacitor 296 and a lead 242. The capacitor 296 has its other
terminal grounded and the lead 242 is connected via lead 290 and a
diode 298 to slider 300 of a potentiometer 302 connected to high
voltage terminal 219.
The setting of the slider 300 determines the voltage on the lead
290 and thus the minimum voltage on the lead 242. Upon conduction
of the transistor 266 the capacitor 296 is charged to full voltage,
approximately 16 volts, and the gates 179, 187, 209 and 211 are
fully opened and apply the three notes of the chord to the chord
amplifier at maximum amplitude. Assuming that lead 290 is at some
lesser voltage, the capacitor voltage decays to the voltage of lead
290 less the drop across diode 298 and the amplitude of the chord
decays to the level determined by the voltage on lead 290. If no
voltage is maintained on lead 290, the decay is rapid to no
amplitude and thus no sound.
Thus at pulse time V.sub.2 a chord of initially maximum amplitude
is played through the lower manual and decays at a rate and to an
amplitude selected by the student.
It should be noted that if the full value of the resistor 302 is
inserted in the charging circuit of capacitor 296, the gates 179,
etc. are turned fully on and, therefore, the lower manual notes of
the organ play continuously. It has previously been seen that
continuous pedal operation may be achieved while pulsing of the
lower manual notes was affected. It is now apparent that complete
flexibility of continuous play of one part of the organ with
pulsing of another part, pulsing of both parts or continuous play
of both parts is available.
Continuing with the operation of the system in waltz mode, it will
be noted that the terminal 65 of the ramp generator of FIG. 1 is
permanently connected to the terminal 254 of the waltz switch and
in waltz operation is connected to the terminal 256 permanently
connected to the E terminal. The E terminal is connected to the
base of the transistor 266 so that upon conduction of the
transistor 55 a negative pulse is applied to the base of the
transistor 266 to render it conductive. Thus the notes to the chord
amplifier are again pulsed. The bass gate comprising the transistor
282 is not pulsed at either the v.sub.1 or V.sub.2 beats, since the
bass notes are to play only upon the downbeat which is sensed on
the lead 8 at the V.sub.3 beat. The next measure which is achieved
after the voltage on the bus 8 exceeds the voltage on the bus 46 by
two diode drops, begins when the voltage on bus 8 falls to
approximately 11/2 1/2 volts, which produces the negative pulse on
bus 8 necessary for the operation of the base trigger transistor
282, and simultaneously produces a positive pulse at the collector
of transistor 60 which is capacitively coupled to transistor 280,
whose firing changes the state of the flip-flop 190 so that the
fifth frequency will be played through the pedal part of the organ.
The sequence of the second measure as to the second and third
pulses is the same as in the first measure and therefore the
desired frequency components of the various beats are achieved.
Referring now specifically to various other rhythms of the organ,
the rock rhythm is now considered. The rock switch is depressed and
the terminal 316 of the rock switch is connected to terminal 318
and terminal 320 is connected to terminal 322. Under these
conditions, with the waltz switch now up, the pulses on terminal 65
of the ramp generator are applied to a contact 324 of the waltz
switch via the contact 254. These pulses are applied through the
upper right contacts generally designated by the reference numeral
326 of the swing switch and thence to the contact 316 of the rock
switch. The contact 318 is wired to a contact 320 of the swing
switch which is also permanently wired to a terminal 322 of FIG. 8
which is connected in the bass circuit of the bass gate transistor
282. The terminal 320 of the rock switch is connected to terminal
324 of the waltz switch which is permanently connected to a
terminal K in FIG. 7 of the drawings. The terminal K is directly
connected to the collector of the transistor 326 which is also
connected through a resistor 328 to high voltage terminal 330. The
terminal 320 is also connected to the terminal 322 of the rock
switch when the rock switch is depressed and thus is connected to a
terminal G in FIG. 8. Terminal G is connected via matrix diode 325
to the bass circuit of the transistor 282 of the base switch
amplifier.
In the rock type of rhythm in the first half-measure, the root and
chord are played at the time of the first and second pulses
respectively, and during the second half-measure fifth-chord-fifth
are played in that sequence. The third beat in the first
half-measure must be suppressed in the pedal circuit. The
transistor 326 has its bass connected through a resistor 340 and
diode 342 to the collector of the transistor 194 and through a
resistor 344 and diode 346 to the collector of transistor 192. It
should be noted that the junction of the resistor 340 and diode 342
is connected through a resistor 348 to the collector of transistor
184 and the junction of resistor 344 and diode 346 is connected
through a resistor 350 to the collector of transistor 160. In
consequence, during each first half-measure the transistor 326 is
turned on and via the K & G contacts in FIGS. 6 and 8,
respectively, grounds the junction of two capacitors 332 and
prevents any pulse that is applied to terminal 322 from triggering
transistor 282 during the interval that transistor 326 is turned
on. During the second half-measure, however, due to switching of
the flip-flop 190, the transistor 326 is rendered nonconductive and
releases the junction of the two capacitors 332 so that the third
pulse of the ramp voltage cycle maybe transmitted through the
transistor to affect the desired pulsing. It should be remembered
that the third voltage pulse is connected to the terminal 322 in
the base of the transistor 282 through the rock and waltz
switches.
The fox trot mode of operation is next considered. In the fox trot
only the first and second pulses of the ramp generator are employed
to play through root chord fifth chord in each measure. It should
be noted that in the fox trot mode no connections are made to the
switch and the switch is present due to the mechanical interlocks
between the various switches that prevents more than one switch
being depressed at one time. Thus depression of the fox trot switch
merely releases any previously depressed rhythm switch. Under these
conditions the terminal 254 of the waltz switch on which the third
pulse of the ramp voltage generator appears although connected
through various switch contacts of the waltz and the swing switches
eventually deadens in the Latin rhythm switch and therefore is not
connected to any portion of the circuit. Thus the bass gate
including transistor 282 and the chord gate including transistor
266 are pulsed only on the first and second pulses, respectively.
The transistor 282 is permanently connected to the bus 8 and the
transistor 266 is permanently connected to terminal 61 of the ramp
generator. The chord gate 266 is under control of the transistor 60
and the bass gate 282 is under control of the bus 8.
Turning now to the swing mode of operation, the swing switch which
is generally designated by the reference numeral 352 is depressed
interconnecting contacts 354 and 320 thereby applying the voltage
appearing at the collector of the transistor 60 of the ramp
generator to the terminal 320 which wired to the terminal 322
connected in the base of the transistor 82.
The operation of the swing mode is essentially the same as in the
fox trot with one exception. Due to the connection of the second
pulse in each half measure to the base of the transistor 282 the
terminal 310 or the S terminal of FIG. 7, which is connected to the
pedal diode gate 240 in FIG. 5, is pulsed on every second note.
Therefore, in addition to the rhythm of the fox trot; that is, root
chord fifth chord, the root and fifth notes alternatively are
played through the pedal circuit at the second and fourth beats of
the rhythm.
The Latin rhythm is similar to but at twice the frequency of the
waltz rhythm. Specifically, in the waltz each ramp is equal to one
measure whereas in the Latin rhythm there are two ramp voltages per
measure. The structure of the frequency content of the pulses is
the same except on the last beat of each half-measure. In the Latin
rhythm during the third beat of each half-measure the chord is
sounded through the accompaniment manual while the root and fifth
parts of the chord are sounded through the pedal in
alternation.
Referring again to the switches of FIG. 7, the Latin switch is
generally designated by the reference numeral 354. When the Latin
switch is depressed its contacts 356 and 358 are connected
respectively to contacts 360 and 362. The contact 360 is connected
to the terminal 320 of the swing switch and therefore is connected
to the terminal 322 in the base of the transistor 282 while the
contact 362 is connected to the terminal 256 of the waltz gate
which is connected to the terminal E in the base of the transistor
266 and thus receives the third beat of each ramp as does the
terminal D. Also when the Latin switch is depressed its terminal
364 is disconnected from the terminal 366 and thus the G and K
terminals are disconnected.
The transistor 266 now receives the second pulse of each beat by
direct connection to transistor 60 and also the third pulse of each
beat via the terminal E. The bass gate 282 receives the first pulse
of each ramp by direct connection to bus 8 and receives the third
pulse of each ramp via the terminal 322. Thus in the Latin mode,
the root frequency is played through the pedal circuits on the odd
down beats and the third beat of each measure. The fifth frequency
is played through the pedal circuits on the fourth beat and the
sixth beat of each measure. The chord is played through the manual
circuits on the second, third, fifth and sixth beats of each
measure due to application of the voltage V.sub.1 to the terminal E
and thence to the transistor 266. The flip-flop 190 is switched
during the first and fourth beats due to the action of the
transistor 280 so that on the second half-measure the play is
fifth-chord-chord with the fifth also being gated through the pedal
gate on the third beat of that half-measure.
The diodes 265 and 289 in the bass circuit of manual trigger
transistor 266 and diodes 285 and 325 in the base circuit of the
pedal trigger transistor 282 comprise a diode switching matrix
which by appropriate routing of signals permits selection of the
application of various beats to various rhythm sections of the
system. This matrix may be expanded as desired to provide
accompaniment for various other desired rhythms.
Mention should be made of the downbeat tempo light 274 and its
operation during various operations of the system. During the waltz
operation the terminal L is connected to the terminal M through the
contacts 262 and 264 of the waltz switch. Thus, whenever the
transistor switches 30 and 36 are rendered conductive and discharge
the capacitor 2 for the fly-back operation on the sawtooth voltage,
the transistor switch 60 is rendered nonconductive and a positive
pulse is applied to the base of the transistor 280. This pulse
produces conduction of the transistor 280 which as indicated is
employed to set the flip-flop 190. Concurrently the transistor
develops a negative going pulse on terminal L. The negative pulse
on terminal L is applied to the base of the transistor 272
rendering it conductive and turning on transistor 370 which now
turns on the tempo light. The transistor 370 is shunted by a
resistance 372 which maintains a sufficient current through the
light 274 to maintain it just below illumination temperature. Thus,
a large current is not required through the transistor 370 to
produce illumination the lamp and rapid operation is achieved. The
transistor 280 is rendered conductive whenever the ramp voltage
falls and in the waltz operation this is in the beginning of every
measure. Therefore the tempo light operates at the beginning of
each measure.
During operations of all other rhythms, the L terminal is connected
to the K terminal connected in the collector circuit of the
transistor 326 via contact 262 and 324 of the waltz switch. Thus
the tempo light is now driven by the transistor 326 which is
rendered conductive as previously indicated only at the beginning
of each measure, due to the off state of one of the transistors 60
or 184 and the conduction of either transistor 192 or 194. Thus the
light 274 is illuminated on every other ramp voltage only and then
only when the pedal root note is played; that is, the first note of
the measure.
As previously indicated it is a feature of the present invention to
render the chord attachment of the present invention inoperative if
two notes are played in the selected octave of the lower manual and
to revert to normal organ operation if three notes are played in
the selected octave of this lower manual. The rational is that if
two notes are struck it is an error but the organ does not know
which note was supposed to be struck. If three notes are struck a
full chord has been played and therefore the player wishes to take
over control of the chord effects himself or herself.
The circuits for accomplishing the above results comprise
transistors 374, 376, 378, and 380. The transistor 374 is rendered
conductive whenever a single note is played and has its collector
connected via a resistor 382 to a bus 384 which is connected to the
base 42 of the transistor 40. Whenever a single note is played the
voltage of the collector of the transistor 374 goes negative and
the sustaining voltage is removed from the base 42 of the
transistor 40 causing the transistor to shut-off at the start of
each note played.
If a key is depressed for only a short interval and another key
depressed rapidly, a downbeat will still sound. Upon release of a
key the transistor 374 again becomes nonconductive, the transistor
40 saturates and the capacitor 2 is charged at a rate faster than
the fingers can hit a new key. Therefore upon the second depression
of the same key, a downbeat is produced.
Returning to the two and three note detector circuits, emitter 386
of transistor 376 is connected to a bus 388 which is connected
through an upper terminal 390 of a rhythm only switch 392 to middle
terminal 394 of the switch and via a lead 396 to terminal 252 of
the ON-OFF switch 244 which when depressed connects the terminal
252 to the contact 250 which in turn is connected to a high voltage
398. The bus 398 is connected to the terminal 330 to which high
voltage, roughly 16 volts positive, is applied. Emitter 400 of
transistor 387 is connected to the emitter 386 of transistor 376
and the base of the transistor 378 is connected through a resistor
402 to the voltage bus 388. The base and collector of transistors
376 and 378 respectively are connected together and through a
resistor 404 and resistor 406 of the junction of the base of the
transistor 378 and the resistor 402. The emitter of the transistor
380 is connected to the junction of the resistors 404 and 406 while
its collector is connected to ground through resistor 408. Its base
is connected to the lead or bus 102 to the key switches of the
selected octave of the lower manual and is also connected through a
resistor 410 to a junction of the resistors 404 and 406.
The operation of the circuit is such that when a single note is
pressed enough current flows through the resistors 402 and 406 via
lead 102, switch 100 to ground to turn on the transistor 376 and
thus apply a positive voltage to the base of the transistor 374 and
turn it on. When two keys are depressed a sufficient current flows
through the resistor 402 to turn on the transistor 400 which now
shorts the base to emitter circuit of the transistor 376 turning
off the transistor 376. When the transistor 376 is off the
transistor 374 is also rendered nonconductive, the transistor 40 is
now conductive and therefore the ramp voltage cannot be generated.
If a third key is depressed the same action as when two keys are
depressed occurs but at this time the transistor 380 is also
rendered conductive. Upon the transistor 380 being rendered
conductive a positive voltage appears at its collector which is
transmitted via a lead 412 to the base electrode of a transistor
414. Upon becoming conductive the transistor 414 shorts bus 416 to
ground which is connected to gate terminal 418 of a FET 420. The
FET is rendered conductive and connects a terminal U through the
FET to the terminal 216 which is connected to the terminal A in
FIG. 5. As previously indicated terminal A is connected through the
accompaniment manual filters to the organ to the speaker system via
the tab switches. The terminal U has applied thereto all of the
lower manual notes of the organ.
Thus when a single note is played the circuits of the present
invention operate in the manner as programmed by the organist. If
two notes are depressed the circuits are rendered inoperative and
if three notes are depressed then standard organ operation is
effected by connecting the terminal U to the accompaniment manual
filters.
It should be noted that the collector of transistor 374 is also
connected via a bus 422 to the tempo light control, more
specifically the base of the amplifier 72. Thus, whenever a key is
depressed a light is turned on. The connections of the terminals M,
K and L being employed primarily for the subsequent downbeats
rather than the first downbeat.
Various secondary functions of the circuits of the present
invention are required to provide proper operation relative to
certain block-out and transient features. For instance, there is
provided a transistor 428 having its base electrode connected to
the lead 422 and thus to the collector of the single note detector
transistor 374. When the single note detector amplifier 374 is on
the transistor 428 is off and applies a high voltage to a terminal
430 which is connected to the terminal V of FIG. 5. The high
voltage applied to the terminal V is connected to trigger amplifier
431 of the pedal keyboard of the conventional organ. The high
voltage applied saturates the trigger amplifier and prevents
playthrough from the pedal keyboard during chord operation.
The collector of the transistor 428 is also connected to the base
of transistor 432 so that when the voltage on collector 428 is high
the transistor 432 is turned on and shorts to ground terminal 440
bearing the notation in a circle P.sub.T which also appears in FIG.
5. The terminal P.sub.T is connected to lead 436 having thereon the
trigger pulse to the pedal rhythm percussion section of the organ
and is also connected through a diode 437 to the input to the pedal
diode gate 240. The pedal diode gate 240 has a capacitor 438
therein which serves the same function relative to the pedal
circuit as the capacitor 296 of FIG. 8 serves relative to the lower
manual notes. The grounding of the point P.sub.T upon conduction of
the transistor 432 prevents the accidental operation of the pedal
keyboard from effecting the pedal rhythm percussion section or the
charge on the capacitor 438. The diode 437 isolates the P.sub.T
circuit from the trigger circuit of the base trigger gate 282 in
FIG. 8. Thus the bass trigger on terminal S maintains control of
pulsing of the pedal diode gate 240 in spite of accidental
operation of the pedal keyboard.
Another feature of the present invention deals with a problem
related to changeover from chord to normal operation. If a student
is playing the organ in a chord mode and then immediately switches
into normal operation by pressing three keys, a chord on his own, a
residual charge on the capacitor 438 can produce problems. The
signal on terminal 217 disappears from the pedal divider 216 but a
signal may be generated almost immediately at the pedal keyboard so
that there may be a short interval during which the signal at the
pedal keyboard may be gated through the pedal diode gate due to the
residual charge on the capacitor 438. The duration of such mode
would be short but would be quite audible and therefore must be
prevented.
To prevent this problem, whenever the single note detector,
transistor 374, is turned off, a high voltage is applied to the
base of the transistor 440 connected to the lead 422. The collector
of the transistor 440 is connected to the terminal S so that when
transistor 40 is turned on upon discontinuance of operation of
transistor 374, the terminal S is shorted to ground and the
capacitor 438 is discharged. It should be noted that the coupling
from the lead 422 to the transistor 440 is through a capacitor 442
so that the transistor 440 is only transientally conductive and
does not interfere with normal operation of the S terminal.
Another problem which may arise in the apparatus of the present
invention is as a result of the student inadvertently playing two
keys and then shifting his fingers so as to sustain the one key but
not the other. Such an operation produces problems in the root
fifth flip-flop. When two notes on the keyboard are played, two
conditions can exist. Either both of the transistors 160 and 184
have a positive voltage applied thereto or only one of these
transistors has a positive voltage applied to its base. In the case
where both of the transistors have a high voltage applied to their
bases, the condition of the flip-flop is unknown since a negative
pulse is transmitted substantially simultaneously to both of the
transistors 192 and 194 rendering both of them conductive. Release
of one of the keys causes the voltage on the collector of this
transistor to rise suddenly. However, the root fifth flip-flop 190
is responsive only to negative pulses and, therefore, the release
of the one key when the two buses are initially positive has no
effect. The same condition prevails if only one of the transistors
60 or 184 is rendered conductive by pressing two keys. If the key
that is eventually selected removes the positive voltage from the
one transistor that was conductive then the sudden rise in voltage
at its collector does not affect the flip-flop.
Under these conditions there is no information available to the
root fifth flip-flop switch it to the proper downbeat key. The
transistor 428, in addition to its control of the terminal V, is
employed to overcome this problem. When two keys are played,
transistor 374 is off, as previously explained, and therefore the
transistor 428 is conductive and its collector is grounded. The
collector of the transistor 428 is connected via a lead 450 and
diodes 452 and 454 respectively to the buses 144 and 161. When two
notes are played and the transistor 428 is conductive the buses 144
and 161 are grounded and cannot effect the transistors 160 and 184.
When the second note is released so that only one note is
sustained, the transistor 428 becomes nonconductive to the same
time that the transistor 374 becomes conductive and the buses 144
and 161 are released so that the proper bus may go positive and
render its associated transistor 160 or 184 conductive; producing a
negative pulse at its collector to properly set the flip-flop
190.
Another difficulty which may arise in the operation of the system
is where the player is playing chords himself; that is, playing
three notes in the selected octave of the lower manual at the same
time. A player does not normally release all three keys at one time
and a base note may come through during that interval.
Specifically, if one note is held longer than the other notes, the
circuits normally do not react quickly enough to place the
transistor 374 into conduction before the third note is released.
However, trigger pulses are developed which often trigger an
automatic pedal function through the operation of the transistor
282. It will be remembered that transistor 282 upon the downbeat
couples a signal through capacitor 286 to the automatic pedal
trigger terminal 288 which is designated as the terminal P.sub.P.
This trigger produces an automatic pedal function in the percussion
section resulting in an undesirable effect particularly since it is
untimed and unrelated to the music being played.
The aforesaid problem is overcome by connecting a signal from the
collector of the three-note-sensing transistor 380 appearing on the
lead 412 via a lead 442 to the base of a transistor 444. When the
transistor 380 becomes nonconductive, when any one of the three
notes is released, a capacitor 446 in the base circuit of the
transistor circuit 444 is charged and turns on the transistor 444
for a time interval dependent upon the value of the capacitor 446 a
resistor 448 in its discharge circuit through the base of the
transistor 444. Conduction of the transistor 444 grounds the
terminal 288 and therefore prevents a pulse from playing through to
the pedal percussion section. The time constant of the capacitor
circuit 446-448 is approximately a quarter of a second, after which
the system reverts to normal operation.
The above forms a complete description of the operation of the
continuous chord and chord rhythm operation of the system. There is
now considered the operation of the systems as a rhythm only system
and reference is initially made to FIG. 7 of the accompanying
drawings. Under this condition of operation, the rhythm only switch
392 is depressed and all other switches are released except, of
course, the ON-OFF switch which is also in its down position and
one of the rhythm switches. Under these circumstances contact 394
of the switch 392 is connected to a contact 456 connected to a lead
458. The contact 394 of the switch 392 is connected via a lead 396,
closed contacts 250 and 252 of the ON-OFF switch 242, and the lead
398 to the high voltage supply terminal 330. High voltage is
applied to the lead 458 connected to a bus 460 which supplies
emitter-collector current to the transistors 266, 282 and through
diode 462 to the emitter of the transistor 272. The switch 292 has
another set of contacts 464 and 466 which when closed connect high
voltage on the terminal 466 to the terminal 464 and via a lead 468,
to a terminal 470, to the base of a transistor 428, and through a
resistor 474 to the base of the transistor 160 in the control
circuit of the flip-flop 190.
The voltage at the terminal 470 applies a positive potential to the
base of the transistor 374 and maintains this transistor on thereby
turning off the transistor 40 and permitting the ramp generator to
run free. The voltage at the terminal 470 also turns on the
transistor 414 which grounds the gate electrode of the FET 420 and
permits the normal manual accompaniment to play through the FET
from the terminal U.
The signals from the chord organ as such must be disabled and this
is accomplished by the voltage at the terminal 470 which is applied
through a diode 476 to the base of the transistor 174, the base of
the transistor 176, and the bases of the transistors 206 and 208.
This voltage is sufficiently high to drive each of these four
transistors into saturation and thus prevent any of the locally
derived signals from coming through.
It should also be noted that a diode 480 is connected between the
collector of the transistor 374 and the line 478. The diode 480 is
employed to apply a high voltage to a lead 478 whenever the
transistor 374 is not conducting. When transistor 374 is not
conducting no note should play through the chord part of the organ.
This condition may occur when no note has been struck in which case
there would not be a frequency applied to any of the transistors
174, 176, 206 or 288. This condition may also occur when either of
the transistors 378 and 380 are operating indicating that two or
three notes have been played. Under these circumstances, signals
are applied to the aforesaid transistors and if not blocked may
play through. .However when the transistor 374 is off high voltage
developed on its collector is conducted via diode 480 to the lead
478 again saturate the transistors 206, 208, 174 and 176 so that
they cannot pass signals.
During the rhythm only operation, the trigger pulses to the
percussion section must come through the trigger amplifier 282 but
must not effect the terminal 310 since during normal operation the
pedal diode gate is under control of the pedal trigger from the
pedal keyboard. Therefore when the system is in the rhythm only
mode of operation, high voltage is applied to produce saturation of
transistor 472 to short to ground the junction of the diode 306 and
resistor 482 to prevent triggering signals from reaching terminal
310. The resistor 482 between the diode 306 and the collector of
the gate 282 isolates the collector from the short circuit and
permits signals to be transmitted to the terminal 288 connected to
the automatic pedal trigger circuit for tympany effects, etc.
As previously indicated the lead 468 is connected to the base of
the transistor 160 via a resistor 474. The purpose of this
connection is to insure that upon closure of the rhythm only switch
392 the selected rhythm will start on the downbeat.
When the transistor 374 is turned on, the voltage on the lead 422
falls and couples a negative pulse to the base of transistor 272
causing the tempo light 274 to light. The voltage on the lead 468
causes saturation of the transistor 160 and sets the flip-flop with
the transistor 194 turned off and the transistor 192 on. When
voltage appears on the leads 468 and 422, voltage also appears on
the lead 384 and as previously indicated the ramp generator begins
to operate, or more particularly, the voltage on the bus 8 suddenly
falls for the first rhythmic pulse or downbeat. Thereafter pulsing
of the light is determined by the rhythm selected, i.e. waltz,
rock, etc.
The system is described as providing only root, third and fifth
parts of a chord. Seventh and sixth parts of the chord may also be
provided. Additionally the pedal and chord continuous play controls
may be ganged so that when the continuous play of the pedal is
called for the slider 300 is moved to the top of resistor 302 and
full voltage is maintained on the lead 290.
While I have described and illustrated specific embodiments of my
invention, it will be clear that variations of the details of
construction which are specifically illustrated and described may
be resorted to without departing from the true spirit and scope of
the invention as defined in the appended claims.
* * * * *