US3837254A

US3837254A - Organ pedal tone generator

Info

Publication number: US3837254A
Application number: US00355780A
Authority: US
Inventors: J Southard
Original assignee: CONN C Ltd
Current assignee: CONN C Ltd
Priority date: 1973-04-30
Filing date: 1973-04-30
Publication date: 1974-09-24
Anticipated expiration: 1991-09-24
Also published as: ZA742568B; DE2421028A1

Abstract

Tone generator system including an oscillator comprising a capacitor and unijunction transistor, with pedals applying potentials representing different notes to a constant current source for controlling the same to charge the oscillator capacitor at different rates for producing the frequencies of different notes. A second control of frequency is provided by changing the potential applied to the gate of the unijunction transistor. The gate potential can be reduced to change the oscillator from the frequency of the root note of a chord to that of the 5th note of the chord, for playing a bass rhythm. The oscillator frequency may be in the frequency range of 8 foot tones, and the sawtooth wave may be directly keyed for providing string bass sounds. A frequency divider triggered by the oscillator produces a square wave at one half the frequency, which is summed with the sawtooth wave to provide a sawtooth wave at one half the frequency, or in the 16 foot tone octave. This may be keyed and filtered for providing a 16 foot diapason tone. The square wave may also be keyed and filtered to provide a 16 foot bourdon tone.

Description

United States Patent 1191 Southard [451 Sept. 24, 1974 [75] Inventor: James S. Southard, Elkhart, Ind. i gsxgj Assigneei Conn, -3 Elkhart, Attorney, Agent, or Firm-Mueller, Aichele & Ptak [22] Filed: Apr. 30, 1973 21 Appl. No.: 355,780 [57] ABS TRAC T Tone generator system mcludmg an osclllator comprising a capacitor and unijunction transistor, with [52] US. Cl 84/ 1.01, 84/ 1.03, 84/1.24, pedals applying potentials representing different mes 84/DIG- to a constant current source for controlling the same Cl. t h g th ill t p it t diff t rates f [58] held of Search 84/101 11171 122-1124 producing the frequencies of different notes. A second 84/DIG- 1316- 12 control of frequency is provided by changing the potential applied to the gate of the unijunction transistor. 1 References cued The gate potential can be reduced to change the oscil- UNITED STATES PATENTS lator from the frequency of the root note of a chord to 3,443,463 5/1969 Campbell 84/1.01 that of the 5th no of the o for p y ng a ss 3,538,804 11/1970 George 84/1.0l rhythm. The osc1llator frequency may be in the fre- 3,603,309 1971 ya 2 X quency range of 8 foot tones, and the sawtooth wave 3,609,201 9/1971 Adachl, 84/ 1.01 may p directly keyed for providing string bass 1 Kmepkamp sound A frequency oscillator $23732? {2131} EEK/ 31/183 2x95112929,saaarsflasat,9991192199.?599999i 481 12/1971 Bunger' 84/l'03 which is summed with the sawtooth wave to provide a 316651089 5/1972 stearns ififiz III: 84/l:01 11/1999 Wave at half the 315E219! iH. h..1. 3,706,837 12/1972 Arsem et al. s4/1.03 foot 19 octave- T111? y be keyed and filtered for 3,707,594 12/1972 lchikawa s4/1.03 provldmg a 16 foot dlapason tone. The square wave 3,708,602 1/1973 Hiyama 84/1.03 may also be keyed and filtered to provide a 16 foot 3,740,449 6/1973 Southard i 84/1.0l bourdon tone. 3,743,757 7/1973 Okamoto.... 84/l.03 3,764,722 10/1973 Southard 84/1.03 l6 Clalms, 4 ng gures l2\- 4 |t 5 IB l 2O l 22 I 24) R mule CONSTANT OSCILLATOR SAMPLE KEYER Z' Q Z CIRCUIT cmcun 2332i? 8 FT I BASS a R PEDAL ALTERNATE KEYER DIAPASON KEYBOARD FIFTH 26 45 1 2a ,3o 4 3222 I FILTE AUTOMATIC DIVIDER KEYER BOURBON RHYTHM FT 16' ORGAN PEDAL TONE GENERATOR minim-strewn ml 2 N 2 mom Om O 2 IkrIm mmh zu @ZEPW mmkJE ORGAN PEDAL TONE GENERATOR BACKGROUND OF THE INVENTION There is a large demand for inexpensive electric organs which have a one octave,'or 13 note, pedal board for controlling an independent tone generating system. One such system is described in Pat. No. 3,180,9l8, issued Apr. 27, 1965, to Donald K. Harmon, and assigned to C .G. Conn Limited, the assignee of the present application. Although such tone generators provide only one bass frequency at a time, frequency dividers may be used to simultaneously provide a tone in a lower octave. It is desired to provide tones having different characteristics such as a string bass, a diapason, and a bourdon or flute tone.

In view of the common use of rhythm systems with organs, it is also desired to provide a pedal tone generatorwhich is adaptable to be used in cooperation with a rhythm system. It is desired that the pedal generator 1 be suitable for use in connection with chords, wherein the root tone and'the th tone of the chord are played alternately. Also it is desired that the pedal generator system be adapted to be keyed in accordance with rhythm patterns.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved tone generator system adapted to provide the such an oscillator which produces a sawtooth wave form, and which triggers a divider to produce a square v wave at one half the frequency, with the sawtooth wave and the square wave being combined to provide various wave forms which are keyed and filtered to provide desired pedal tones.

Another object of the invention is to provide a pedal generator system including an oscillator and keyers which are adapted to be controlled by a rhythm system for providing various rhythm effects.

Still another object of the invention is to provide a keyer circuit for use witha rhythm system which prevents double triggering by actuation of the pedal slightly out of tempo with the rhythm beat.

In practicing the invention, a pedal tone generating system is provided wherein the pedals select different potentials from a voltage divider, with the selected potentials controlling a constant current source to charge a capacitor at a fixed rate. A unijunction transistor is coupled to the capacitor to discharge the same, forming an oscillator which provides a sawtooth wave. Waves corresponding to the notes in an octave can be provided by changing the current supplied by the con- ,stant current source, to provide the notes in the 8 foot octave. In addition to control of the frequency of the wave by the current source, the potential applied to the gate of the unijunction transistor can be changed to change the duration of each ramp to thereby control the period and frequency of the produced wave. The change in the gate potential can be controlled by a rhythm system to automatically change the gate potential to change the frequency from the root note of a chord to the 5th note thereof, with the frequency automatically alternating between the root and the 5th tones as desired for a rhythm sound. The oscillator triggers a frequency divider for producing a square wave at one half the frequency of the sawtooth wave, to provide tones in the 16 foot octave. The square wave and the sawtooth wave may be summed to provide a third output, which is a sawtooth wave in the 16 foot octave. The three different outputs may be individually keyed and filtered to provide different pedal tone sounds. The keyers may also be controlled by the rhythm system, to provide desired rhythm effects. The keyer control circuit prevents double triggering of the keyers by operation of a pedal slightly out of tempo with the rhythm beat.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the pedal generator system of the invention;

FIG. 2 is a chart showing waveforms developed in the system of FIG. 1;

FIG. 3 is a circuit diagram of the tone generator system of FIG. 1; and

FIG. 4 is a chart illustrating the operation of the keyer control circuit.

DETAILED DESCRIPTION In FIG. lthe organ pedal tone generation system of the invention is shown in block diagram form. A keyboard 10 controls a tuning network 12 which produces potentials in accordance with the particular notes selected. The keyboard may be a pedal board which is used with an organ having one or more other keyboards or manuals. The potential from the tuning network is applied to a memory circuit 14, which controls a cur rent source 16, which in turn controls the frequency of an oscillator 18. The oscillator 18 produces tones in the 8 foot octave of the organ. The tones from the oscillator 18 are sampled by the circuit 20 and applied to a keyer 22 for producing string bass tones. The tones from keyer 22 are applied through the format filter 24 to the audio system 26.

The output of the oscillator 18 is also applied to a divider 28 which produces tones in the 16 foot octave. The tones from the divider 28 are applied to keyer 30 which keys the 16 foot tones. The 16 foot tones are applied through filter 32 which may modify the shape of the wave to produce the bourdon sounds, and then to the audio system 26.

The 8 foot tones from the circuit 20 are applied to one end of

potentiometer

35, and 16 foot tones from the divider 28 are applied to the other end thereof. The 8 and I6 foot tones are. summed and derived from the intermediate terminal 36 of the potentiometer and applied to keyer 38. The output of keyer 38 is applied through diapason filter 40 to the audio system 26.

In addition to the operations controlled by the keyboard 10, an automatic rhythm system may be provided which produces various beat pulses for different rhythm patterns determined by controls on the rhythm system 45. Outputs from the keyboard 10 and from the rhythm system 45 are applied to an alternate 5th circuit the frequency of the oscillator 18 to produce a different note, as will be fully described. Pulses from the keyboard 10 and from the rhythm system 45 are also applied to the

keyers

22, 30, and 38 to control the same.

In FIG. 2 there is shown the waveforms utilized in the pedal generator system. Line A shows the waveform produced by the oscillator 18, and which is derived therefrom and applied to the sample circuit 20. This is a sawtooth waveform having a frequency in the 8 foot octave. As previously stated, the frequency is controlled by the tuning circuit 12 in response to operation to the keyboard 10 (FIG. 1). The frequency of the oscillator may also be controlled by the alternate 5th circuit 48, as will be described. Line B shows a second output which is derived from the oscillator 18 which is a pulse output produced at the time the sawtooth wave drops. The pulse output B is applied to the divider 28 to cause the divider to produce the square wave output as shown in line C. As previously stated, this is at one half the frequency of the sawtooth wave in line A, and has a frequency in the l6 foot octave. The signal produced at point 36 of the potentiometer 35 is shown in line D of FIG. 2. This is a sawtooth wave having the same frequency as the wave shown in line C. This is formed by the addition of the waves shown in line A and C. Accordingly, the circuit provides sawtooth waves at frequencies in the 8 and 16 foot octaves, and a square wave in the 16 foot octave. The waves after keying are shaped by filters to provide the desired musical wave shapes.

In FIG. 3 there is shown a circuit diagram of the pedal generating system which follows the block diagram of FIG. 1. The keyboard 10 includes two switches 50 and 52 which are operated by each key or pedal. In the system of FIG. 3, l3 switches 50 and 52 are provided for a 13 note pedal board, which provides the notes inan octave from C1 to B1, and including the note C2 of the next higher octave. The notes produced are indicated adjacent the switches.

The switches 50 provide a different potential for each note in the keyboard which is related to the frequency 'of the note. Four voltage divider strings 54, 55, 56 and 57 are provided from a regulated potential applied by conductor 60, which is connected through resistor 61 to the four voltage divider strings. The regulated potential on conductor 60, which is shown in FIG. 3 as +18 volts, is provided by regulator 62 which is energized from the +30 volts supply. Each divider string has a plurality of series connected resistors with taps thereon to produce different voltages. The switches 50, when operated, are each connected to a tap on one of the voltage divider strings, and derives the potential therefrom which is applied to conductor.65. Each of the switches 50 is a double throw switch, and an operated I switch applies the potential through the normally closed contacts of the switches of the pedal board associated with the notes of lower frequency. The arrangement shown is known in the art, being shown in Pat. No. 3,180,918, referred to above. In the circuit shown in FIG. 3, in the event that two switches 50 are operated, only the potential provided by the switch associcharge the same. This potential is applied through resis- 'tor 67 to the gate electrode of field effect transistor 80.

The drain electrode of transistor is coupled to conductor 60 providing the regulated potential, and the source electrode is connected through potentiometer 81 and resistor 82 to ground.

Current source transistor 84 has its base electrode connected to the voltage divider formed by

resistors

82 and 83, and its emitter electrode connected through resistor 85 to the intermediate point on potentiometer 81. The collector electrode of transistor 84 is connected to capacitor 86 and provides a constant current supply to charge this capacitor at a rate which depend upon the bias voltage applied to the gate electrode of the field effect transistor 80.

Connected across capacitor 86 is a unijunction transistor 88 having its base electrode connected through resistor 89 to ground, and its emitter electrode connected to the high potential side of capacitor 86. The gate electrode of unijunction transistor 88 is connected to a voltage

divider including resistors

90 and 91 connected between the regulated potential line 60 and ground. The potential on line 60 is held within close limits by the regulator 62 which can be of known construction. When the capacitor 86 charges to a voltage such that the emitter of transistor 88 rises to the gate voltage, the transistor 88 will conduct to discharge capacitor 86 through resistor 89. The time required for the capacitor to charge will depend upon the charging rate, which is controlled by the field effect transistor 80. Accordingly, the potential applied by the key switches will control the charging rate and the time interval before firings, to thereby control the period and frequency of the wave produced across capacitor 86 by the charge and discharge thereof.

A field effect transistor 94 has its gate connected to the high potential side of capacitor 86, its drain connected to the regulated potential on conductor 60, and its source connected through resistor 95 to ground. This transistor forms a source follower to provide a potential on conductor 96 which corresponds to the voltage across capacitor 86. The source follower circuit, including transistor 94 and resistor 95, forms the sample circuit 20 shown in FIG. 1. Accordingly, a triangular wave is developed on conductor 96, which is the waveform shown on line A of FIG. 2.

The frequency divider 28 shown in FIG. 1, is provided in the circuit of FIG. 3 by the multivibrator including transistors 100 and 102. The two transistors are connected in a bistable multivibrator circuit, with their emitter electrodes connected together and to resistor 89, through which capacitor 86 is discharged. As is well known, the transistors 100 and 102 will be alternately conducting as the'bistable multivibrator changes states. The discharge of capacitor 86 through resistor 89 will produce a positive going pulse thereacross which is directly applied to the emitter electrodes of transistors I00 and 102. These pulses are shown by line B of FIG. 2, and will act to turn off whichever transistor 100 or 102 is conducting, causing its collector potential to rise. This potential is applied to the base of the other transistor turning it on. Inasmuch as the positive going pulse is produced across resistor 89 once during each cycle of the waveform produced across capacitor 86, the multivibrator will change state once during each cycle with the result that a complete cycle is produced by the multivibrator during each 2 cycles of the wave across capacitor 86. A square wave is produced at the collector of each transistor 100 and 102, as shown in line C of FIG. 2, with the square wave being derived in the circuit of FIG. 3 from the collector of transistor 100.

The sawtooth wave on conductor 96 and the square wave on conductor 103 connected to collector of transistor 100, are applied to the summing network 35, which includes

resistors

104, 105 and 106. The summed output is derived by conductor 108 connected to the junction 36 between resistors 105 and 106. The

plication Ser. No. 156,326, filed June 24, 1971, and

now U.S. Pat. 3,740,449.

The alternate 5th circuit is connected to the gate of transistor 88, and includes resistors 109 and 110, diode 111, and resistor 112 connected to the regulated conductor 60. Transistor 114 has its collector connected to the junction between diode 111 and resistor 112, and its emitter connected to ground. A potential is applied from terminal 115 of the rhythm system 45 through resistor 116 to the base electrode of transistor 114 to selectively render the same conducting. This will bring the collector of transistor 114 near ground, so that the junction between diode 111 and resistor 112 will be brought near ground potential. This will effectively connect the resistors 109 and 110, and diode 111 in parallel with resistor 91 to reduce the gate potential applied to unijunction transistor 88. This reduced gate potential will cause the unijunction transistor 88 to fire when capacitor 86 charges to a lower value, to shorten the period of the wave and increase the frequency produced when transistor 114 conducts.

In the event that the switch 50 of an actuated pedal provides a potential to cause the oscillator 18 to operate to produce the note C, the action of the alternate 5th circuit will cause the oscillator frequency to increase to produce the note G. The note G is the 5th note in the chord in which the note C is the root. Accordingly, operation of transistor 114 causes the oscillator to change from the root note C to the 5th note G.

-An external terminal 92 is connected to the gate electrode of unijunction transistor 88, to which potentials can be applied to control the frequency of oscillation, as may be desired. By applying different potentials to terminal 92, the frequency produced by the oscillator formed by capacitor 86 and transistor 88 can. be changed in steps, to provide a walking bass effect, for example.

The keyer 38 for the 16 foot diapason tone includes transistor 120. The sawtooth wave output from point 36 is applied through resistor 121 to the emitter of trandiapason tone. The charge of capacitor 122 is controlled by transistor 125 which forms a two input gate. The base of transistor 125 is connected by resistor 126 to conductor 129 which is connected to terminal 127 of the rhythm system 45. Conductor 129 is also connected to the collector of transistor 131, which is controlled by the signal applied from terminal 130 of the rhythm system. The emitter of transistor 125 is connected to conductor 132 which is connected to the pedal switches 52, so that when any pedal -*(or key) switch is operated, the regulated potential on line 60 is applied to the emitter of transistor 125.

When the rhythm system is not being used, a ground is applied to terminal 127 and through resistor 126 to ground the base of transmitter 125 so that it is rendered conductive. Then when a pedal switch 52 is operated, the potential applied on line 132, which may be plus 18 volts, is coupled from the emitter to the collector of transistor 125 and acts to charge capacitor 122. The collector of transistor 125 is connected to capacitor 122 by diode 134 and resistor 135, which supply current to charge the capacitor. The potential developed across capacitor 122 is applied through resistor 123 to the base of transistor 120 to render the same conducting, so that the diapason tone applied to the emitter thereof is coupled to the collector and applied through capacitor 138 to the base of transistor 140. The rate of charge of capacitor 122 controls the attack of the diapason tone. Transistor 140 amplifies the diapason signal andapplies the same to the diapason filter 40, from which it is applied to audio system 26.

The decay of the diapason tone is controlled by the discharge rate of capacitor 122. When the pedal switch 52 is released or opened, capacitor 122 normally discharges through resistors 123 and 142, and diode connected transistor 143. This discharge rate may be relatively slow to provide a sustain effect. If it is desired to provide a rapid decay of the tone, a negative potential can be applied to capacitor 122 from terminal 145,

through operation of a tab switch of the organ. This potential is coupled through resistor 146 to the capacitor 122, and the negative potential will cause the capacitor 122 to discharge rapidly to reduce the sustain time.

The keyer 22 for the 8 foot tone is similarly controlled by a two input gate formed by transistor 150. This transistor also has its emitter connected to conductor 132, which is connected to the pedal switches 52 to apply the potential on regulated conductor 60 thereto. The base electrode of transistor 150 is connected by resistor 151 and conductor 129 to terminal 127 of the rhythm system 45, and is also coupled to the collector of transistor 131, the base of which is connected to terminal 130 of the rhythm system. The keyer 22 includes transistor 154, having its emitter connected to conductor 96 through capacitor 156 to apply the 8 foot tone thereto. This tone is gated by transistor 154 which controls the attack and decay characteristics of the tone.

When the rhythm system is off and the base of transistor 150 is grounded, actuation of a pedal switch 52 will apply the regulated potential from the emitter to the collector of transistor 150, and across

resistors

158, 159 and 160. The voltage across resistor 160 is coupled through capacitor 162 and across resistor 163 to the base of transistor 165. The potential applied through transistor 150 causes transistor 165 to initially be highly conductive which, in turn, renders transistor 166 conducting. This action results from the current flow tor 154 to be conducted to the collector thereof, and i applied through coupling capacitor 175 to the base of transistor 176. The voltage divider circuit formed by variable resistor 185 and

resistors

186, 187 and 188, applies a potential through resistor 189 to the base of transistor 154 to control the threshold voltage required across capacitor 170 to render transistor 154 conducting. Resistor 188 may be a temperature responsive resistor to compensate the threshold for changes in temperature. The turn on of transistor 154 controls the attack of the 8 foot tone to provide a string bass effect.

Transistor 176 amplifies the string bass signal and applies the same to the'string filter 24 which, in turn, applies the'signal to the audio system 26.

When the pedal switch 52 is released, the charging potential is removed from capacitor 170 and this capacitor discharges through resistor 180 and diode 182, which are connected to terminal 184. The potential at terminal 184 can be controlled between two values by a tab switch of the organ which is connected thereto. Capacitor 170 will initially discharge rapidly to the potential applied at terminal 184, and then continue to discharge at a slower rate through

resistors

172 and 173, and the base-emitter junction of transistor 154. By controlling the potential applied at terminal 184,-the point at which the rapid discharge terminates can be controlled, to thereby control the decay characteristics of the string bass tone.

A further discharge path is provided for capacitor 170 through the collector-base junction of transistor 166,

resistors

167 and 168, diode 190 and resistor 191 connected to terminal 192. Terminal 192 is selectively connected to ground by an organ tab switch. When terminal 192 is grounded, capacitor 170 will discharge very rapidly so that there will be substantially no sustain action, and the string bass tone will terminate abruptly. The action of the circuit to charge and discharge capacitor 170 is described and claimed in my Pat. No. 3,617,605 issued Nov. 2, 1971. Resistor 173 is provided in parallel with resistor 172 in the circuit to provide the desired discharge characteristics. This is required since the part of the circuit enclosed by dotted lines may be provided as an integrated circuit for general application. The external resistor 173 modifies the decay characteristics of the keyer and provides the desired characteristics for a particular application.

When the rhythm system 145 is operative, the ground will be removed from terminal 127 and applied to terminal 128, and automatic rhythm beat pulses will be applied to terminal 130. These pulses are applied across

resistors

194 and 195 and through capacitor 196 to the base of transistor 131. This will cause transistor 131 to conduct on each beat to effectively ground conductor 129 to render the gate transistor 125 in the dia pason keyer circuit, and the gate transistor 150 in the string bass keyer circuit conducting. Accordingly, when a pedal is operated to close a switch 52, the keying potential will be intermittently applied through the transistors and in response to the beat pulses from the rhythm system.

Keyer 125 will operate when a pedal is first operated to close a switch 52 without receiving ground from transistor 131 in response to a rhythm pulse. This results from the ground at terminal 128 being applied through diode 198, capacitor 199 and resistors 206 and 126- to the base of transistor 125. The operated switch 52 applies positive potential through resistor 207 to charge capacitor 199 to turn off the keyer 125 after a short time. The keyer 125 will therefore operate only once from actuation of a pedal, but will be operated in response to rhythm beat pulses by action of transistor 131 to ground conductor 132, which grounds the base of transistor 125.. Keyer 150 for the string bass tone is not keyed in this way, as there is no capacitor connected to the base of transistor 150.

Terminal 200 is connected to conductor 132 so that the potential applied by actuation of a pedal switch 52 can be applied to an external auxiliary device connected to the organ, or an external potential can be applied at this point to operate the keyers. Similarly, terminal 202 is connected to the collector of transistor 150, so that the potential applied therefrom which controls the string bass keyer can be applied to an external auxiliary device, or an external potential can be applied to operate the keyer.

A large capacitor 205 can be connected from terminal 200 to terminal 203 which is connected to the emitter of transistor 131, to prevent double triggering of transistor 131. FIG. 4 shows the action of this circuit when the pedal is operated at a time slightly after a rhythm pulse is applied, with the rhythm pulses being shown by line E and the operation of the pedal and switch 52 by line F. When the first rhythm pulse E, is received, the transistor 131 will be rendered conducting. Then when a pedal is operated and a switch 52 is closed, the regulated potential is applied through the switch to conductor 132 and to terminal 200. This potential will be applied through capacitor 205 to the emitter of transistor 131, so that transistor 131 will not conduct in response to the next rhythm pulse E as the emitter potential is above the potential of the pulse applied to its base. The potential applied to the emitter of transistor 131 will decrease exponentially as capacitor 205 charges, as shown by curve G which is superimposed on the pulses E. Transistor 131 will conduct in response to the next rhythm pulse 13;, as the emitter potential has fallen below the potentialof the rhythm pulses from terminal 130. Transistor 131 is, therefore, rendered conductive to'apply a ground to conductor 129 and cause

transistor gates

150 and 125 to conduct and turn on the diapason and string bass keyers.

The action of capacitor 205 creates a time when rhythmpulses cannot fire the keyers just after switch 52 closes, eliminating a double triggering when the pedal is played slightly out of tempo, which is objectionable musically. Other circuit arrangements can be provided to prevent such double triggering.

The tone generator circuit which has been described has been found to be highly effective to provide pedal tones for an electric organ. The circuit can be used with a rhythm system so that the pedal tones are provided capacitor means for developing a voltage wave, current supply means connected to said capacitor means for supplying current thereto to charge said capacitor means so that the voltage thereacross rises linearly,

switch means connected to said capacitor means for discharging said capacitor means, said switch means having a control element for receiving a control potential which causes said switch means to conduct and discharge said capacitor means in response to a voltage across said capacitor means which reaches said control potential,

circuit means connected to said control element of said switch means for applying a first potential to said control element which causes said switch means to conduct to discharge said capacitor means to produce a wave thereacross which has the frequency of a first musical note, and

control means connected to said circuit means for causing said circuit means to establish a second potential which causes said switch means to conduct to discharge said capacitor means to produce a wave thereacross which has a frequency different from said frequency of the first musical note.

2. A tone generator circuit in accordance with claim 1 further including tuning means connected to said current supply means for causing said current supply means to supply currents of different values to charge said capacitor means at different rates, with the values of the currents supplied being related tosaid first potential applied to said switch means by said circuit means so that the waves across said'capacitor means have the frequencies of different musical notes.

' 3. A tone generator circuit in accordance with claim one half the frequency of the wave developed across said capacitor means, and combining means coupled to said capacitor means and to said frequency divider means to provide a resultant wave.

5. The circuit of claim 4 further including a first keying means coupled to said combining means for keying the resultant wave produced thereby, and second keying means coupled to said capacitor means for keying the wave developed thereacross.

6. The circuit of claim 5 further including first and second gate means for controlling said first and second keying means, with each of said gate means having a first input coupled to a keyboard and a second input coupled to rhythm means.

7. The circuit of claim 1 wherein said switch means is formed by a unijunction transistor having a gate electrode, and said gate electrode forms said control element of said switch means.

bination,

oscillator means for producing waves corresponding to musical notes including capacitor means across which the waves are developed, means connected to said capacitor means for applying current thereto to charge said capacitor means, and switch means connected to said capacitor means for discharging the same in response to a voltage across said capacitor means which reaches a predetermined potential,

a control circuit connected to said switch means and applying a control potential to said switch means for actuating the same, said control circuit including first means for establishing a first control potential which causes said switch means to conduct to discharge said capacitor means to produce a wave thereacross which has the frequency of a first musical note, and second means coupled to said first means and causing said first means to establish a second potential which causes said switch means to conduct to discharge said capacitor means to produce a wave thereacross of a higher frequency of a second musical note, I

gating means coupled to said capacitor means for selectively passing the waves developed thereacross and controlling the attack and decay of the musical notes produced by said waves, and

rhythm means coupled to said second means of said control circuit and to said gating means for controlling said second means and said gating means in accordance with a rhythm pattern.

9. An organ system in accordance with claim 8 wherein said, gating means includes means for changing the decay of the waves passed thereby.

10. An organ system in accordance with claim 8 further including a keyboard coupled to said gating means for controlling the same.

11. An organ system in accordance with claim 10 including means coupled to said keyboard and to said means for applying current to said capacitor means for controlling such current in accordance with the operation of said keyboard.

12. An organ system in accordance with claim 10 further including circuit means coupling said rhythm means and said keyboard to said gating means for producing a gating potential and applying such potential to said gating means in response to a pulse from said rhythm means and operation of said keyboard, and means coupled to said circuit means for disabling said circuit means for a predetermined time after the gating potential is produced.

13. An organ tone generator system including in combination;

oscillator means for producing waves corresponding to musical notes,

gating means coupled to said oscillator means and responsive to a gating potential for selectively passing the waves from said oscillator means,

a control circuit for said gating means for applying a gating potential to said gating means,

keyboard means coupled to said control circuit for selectively applying a potential thereto, rhythm means coupled to said control circuit for applying thereto pulses corresponding to the beats of a rhythm,

said control circuit being responsive to the potential from said keyboard and the pulses from said rhythm means to produce a gating potential to operate said gating means to pass the wave from said oscillator means, and

disabling means coupled to said control circuit and operative in response to the gating potential to disable said control circuit and prevent the application of the gating potential to said gating means for a predetermined time period.

14. The organ tone generator system of claim 13 wherein said control means has an input for receiving pulses from said rhythm means and an output for applying the gating potential to said gating means, and including disabling means coupled from said output to said input for disabling said control means for a predetermined period. v

15. The organ tone generator system of claim l4 wherein said disabling means coupled from said output to said input is a capacitor which applies a disabling potential to said input which decrease exponentially to a value such that said input respond to said pulses applied thereto.

16. The organ tone generator system of claim 13 wherein said gating means includes first and second gates and said control means includes first and second circuit portions coupled to said first and second gates, respectively, with said first circuit portion causing operation of said first gate in response to the potential from said keyboard and causing further operation of said first gate in response to pulses from said rhythm means.

Claims

1. A tone generator circuit including in combination, capacitor means for developing a voltage wave, current supply means connected to said capacitor means for supplying current thereto to charge said capacitor means so that the voltage thereacross rises linearly, switch means connected to said capacitor means for discharging said capacitor means, said switch means having a control element for receiving a control potential which causes said switch means to conduct and discharge said capacitor means in response to a voltage across said capacitor means which reaches said control potential, circuit means connected to said control element of said switch means for applying a first potential to said control element which causes said switch means to conduct to discharge said capacitor means to produce a wave thereacross which has the frequency of a first musical note, and control means connected to said circuit means for causing said circuit means to establish a second potential which causes said switch means to conduct to discharge said capacitor means to produce a wave thereacross which has a frequency different from said frequency of the first musical note.

2. A tone generator circuit in accordance with claim 1 further including tuning means connected to said current supply means for causing said current supply means to supply currents of different values to charge said capacitor means at different rates, with the values of the currents supplied being related to said first potential applied to said switch means by said circuit means so that the waves across said capacitor means have the frequencies of different musical notes.

3. A tone generator circuit in accordance with claim 1 wherein said second potential produced by said circuit means is related to said first potential to produce a second musical note which is related to said first musical note as the fifth and root notes in a chord.

4. A tone generator circuit in accordance with claim 1 further including frequency divider means coupled to said switch means for producing a rectangular wave at one half the frequency of the wave developed across said capacitor means, and combining means coupled to said capacitor means and to said frequency divider means to provide a resultant wave.

8. An organ tone generator system including in combination, oscillator means for producing waves corresponding to musical notes including capacitor means across which the waves are developed, means connected to said capacitor means for applying current thereto to charge said capacitor means, and switch means connected to said capacitor means for discharging the same in response to a voltage across said capacitor means which reaches a predetermined potential, a control circuit connected to said switch means and applying a control potential to said switch means for actuating the same, said control circuit including first means for establishing a first control potential which causes said switch means to conduct to discharge said capacitor means to produce a wave thereacross which has the frequency of a first musical note, and second means coupled to said first means and causing said first means to establish a second potential which causes said switch means to conduct to discharge said capacitor means to produce a wave thereacross of a higher frequency of a second musical note, gating means coupled to said capacitor means for selectively passing the waves developed thereacross and controlling the attack and decay of the musical notes produced by said waves, and rhythm means coupled to said second means of said control circuit and to said gating means for controlling said second means and said gating means in accordance with a rhythm pattern.

9. An organ system in accordance with claim 8 wherein said gating means includes means for changing the decay of the waves passed thereby.

13. An organ tone generator system including in combination; oscillator means for producing waves corresponding to musical notes, gating means coupled to said oscillator means and responsive to a gating potential for selectively passing the waves from said oscillator means, a control circuit for said gating means for applying a gating potential to said gating means, keyboard means coupled to said Control circuit for selectively applying a potential thereto, rhythm means coupled to said control circuit for applying thereto pulses corresponding to the beats of a rhythm, said control circuit being responsive to the potential from said keyboard and the pulses from said rhythm means to produce a gating potential to operate said gating means to pass the wave from said oscillator means, and disabling means coupled to said control circuit and operative in response to the gating potential to disable said control circuit and prevent the application of the gating potential to said gating means for a predetermined time period.

14. The organ tone generator system of claim 13 wherein said control means has an input for receiving pulses from said rhythm means and an output for applying the gating potential to said gating means, and including disabling means coupled from said output to said input for disabling said control means for a predetermined period.

15. The organ tone generator system of claim 14 wherein said disabling means coupled from said output to said input is a capacitor which applies a disabling potential to said input which decrease exponentially to a value such that said input respond to said pulses applied thereto.