CA1053490A - Arpeggio system for electronic organ - Google Patents

Abstract

ABSTRACT

An automatic arpeggio system for an electronic organ, in which playing of a chord, or a single note, turns on tone signal gates for the played notes, and, at will, all octavely related notes, and initiates action of an assynchronous up-down multi-stage counter which sequentially reads out only the turned on gates, in sequence, either in an up-scan only, or up and then down. The gates lead to tone color filters, amplifiers and loudspeakers. Those counter stages which are selected to turn on gates are constrained to act a clock controlled bistable flip-flops, while the remainder act as monostable flip-flops with a time constant of the order of 30. microseconds, so that their set and reset involves inadequate time elapse to effect sounding of a note by closing of a tone gate.

Description

Background ~53~
In Canadian Patent 939,941 and Canadian Patent application S.N. 14~,192 assigned to the assignee of the present invention, an alltomatic arpeggio system is disclosed which performs, in a brc~ad sense, the arpeggiation functions of the present invsntion.
The above specifications disclose utilizing a ramp voltage for scanning the tone output gates of an electronic organ upwardly, and a triangular voltage wave for the up-down mode. The ramp or triangular wave must se~uentially scan all po~sible notes which are called forth in an organ employing the system, plus all notes of corresponding nomenclatures, but must pass over all other notes. To accomplish this, a string of series connected diodes is scanned by the ramp vol~age, certain of which, corresponding with non-called for notes, are shorted, and the others left open circuited in response to playing of keys. This has the effect of eliminating only the shorted diodes from the system during any scan, up or down, but scanning of the unshorted diodes sounds notes. Wmen the ramp has up-scanned through the last of the conductive diodes, it can be caused to reverse and to scan the diodes in a descending sense, or it can be set for a further up-scan, and the slope of the ramp or triangular wave establishes the tempo of the arpeggio.
In the system of the present invention, the ramp and diode scanning system is replaced by an up-down assynchronous counter chain, acting as a commutator. Certain of the flip-flop elements of which, corresponding to uncalled for notes and notes octavely related to the latter, are scanned through so rapidly that no sound is heard, whereas the actuated keys effect a sufficientl~ slow per stage operation that corresponding sounds

- 2 - ~ ~

- ` ~053490 are heard. I~e counter is constituted of flip-flops which have two modes of operation, depending on whether or not an associated key of an organ is actuated. In one mode of operation the flip-flop acts as a mono-stable device with an operating time of about 30. microseconds. When a key is actuated, the associated flip-flop i~ made bistable, and is timed by a clock. The tempoof an arpeggio is therefore controllable in terms of clock frequency.
SUM'.~IARY OF TEIE INVENTION
A system for automatically generating arpeggios and strums in an electronic organ, including an up-down counter composed of a chain of flip-flops which can be individually set to operate monostably or bistably, and a clock to time the bistable stages, used to sequentially open tone gates for preset durations. Those flip-flops which relate to actuated key~ of the organ and noke~
o~ the same nomenclature but hiyher in pltch are operated as bistable devices controlled by the clock, and those relating to unactuated keys operate as mono-stable devices of very short time constant (30. microseconds) independent of the clock. Controls are provided which establish various operational modes of the system -- tl) a normal mode, in which tones sound as played;
(2) a strum mode, in which notes directly called for by actuated keys are played in up-sequence only; (3) an up-arpeggio mode in which all notes of a given nomenclature including those of higher octaves and the same nomenclature, called for by actuating a key or keys, are played in an up-arpeggio sequence; (4) an up-down arpegyio mode, in which each sequence (3) is automatically followed by a down-arpeggio, involving the no-tes called or by the actuated keys. The down arpeggio can be interrupted and the up-arpeggio re-established by playing a note or notes during the down arpeggio;

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~053~90 (5) a multi-tone mode which can be used in conjuncticn with the above strum mode or either arp~ggio mode, in which the actuation of a key during a strum or arpeggio sequence introduces an addi-tional strum or arpeggio sequence. Sirlce notes can be added to or substracted from any up arpeggio, or added to or substracted from a called-for sequence, during any down arpeggio, simultaneous complex arpeggio sequences of tones can be induced, in the (5) mode, though all must proceed in the same direction at any given time.

BRIEF DESCRIPTIO~ OF THE DRAWINGS
Figure 1 is largely a block diagram of a system for auto-matically generating arpeggios, according to the invention.
Figure 2 is a circuit diagram of certain controls employed in the ~ystem of Figure l;
Figure 3A and 3B taken together constitute a circuit dia-gram of an up-down counter and controls therefor, corresponding with the block diagram of Figure 1 and responsive to the controls of Figure 2;
- Figure 4 is a logic daagram of the system of Figures 3A, 3B;
Figure 5 is a tone flow diagram of the system of Figures 3A, 3B;
Figure 6 is a circuit diagram of an alternative pedal controlled cloek, utilizable in the system of Figures 3A and 3B;
and Figure 7 is a circuit diagram of a system for avoiding double top notes in up-down arpeggios.

lOS~490 DETAILED DESCRIPTION OF THE DRAWINGS
In Figure 1, key switches 10 are illustrated, and are label~d in respect to the notes called for. A positive voltage source 20 proceeds via a "note played detector" 21, common to all the key switches 10. The note played detector 21 provides a control voltage on lead 22 regardless of which key or keys 10 is actuated. If at least one key is actuated, this voltage is applied to sequential readout 13, to initiate and control its operation. The latter is a multi-stage counter.
Each key has a signal gate, as 23, for C2, 24 for C2# and each signal gate is connected to a tone signal source, as 25 for C~, which is of appropriate frequency, and of square wave charac-ter in the usu~l case. These key gates 23, 24 etc. are all short sustain gates, to enable staccato piano simulation. Long sustain piano ef~ects are achieved by connecting a long sustain gate in cascade with each short sustain gate, as in Canadian patent 939,941.
All C switches of a manual connect to a bus 30, all C#
switches to a bus 31 and all D switches to a bus 32, in each case via an isolating resistance 34, and so on for the remaining notes.
There are therefore four sets of three busses per set to cover all the octaves and all the notes of each octave, each octave being divided into four sets of three adjacent notes per set, three having been selected as economical, and not as a matter of princi-ple. Only one set of busses is illustrated. There ~hus is pro-vided a C bus, to which all Cs are connected, a C# bus to which all C#s are connected, and so on, and it is these busses, rather than the key switches that are connected to key on the signal gates.

.A`' ` -``"- 1053490 '~ as C2, C2#, D2. The latter set has its outputs tied together at c a common output termlnal 35, and the signal output terminals 24b lead to tone gates 36, 37, 38, 39 etc. which have long sustain capability. The latter four gates cover the first octave, but each octave has its set of four tone gates. A total of twelve tone gates is illustrated, but to cover an organ keyboard of 61 notes, twenty tone gates are employed, the highest frequency tone gate collecting signal from four, instead of the usual three, signal gates. All the tone gates of the system lead to a common bus 40, which in turn proceeds to tab selected tone filters 14, conventional in electronlc organs. The filters lead to amplifier 15 and loud-speaker 16. The tone gates are turned on or read out in sequence by sequential readout 13, for the arpeggio mode of the system, ,~
or for the 9trum mode, in which a guitar i9 simulated. If the ~ piano mode is desired, sequential readout is disabled and all ,~ energized tone gates are enabled simultaneously, by means not shown~in Figure l. However, the readout is so accomplished that only~tone~gates which have signal present at~their input are read out,~;~or scanned, and the others are effectively skipped.
The sequential readout has a limited number of readout positions, specifically 20, there being one readout position for each of tone gates 36, 37, etc. Each readout position is enabled or~disabled, according to a control voltage on each of leads 45, ;46, etc., whlch proceed each from a group of three key switches, as C2, C2#, D. If a position is enabled it is read out in , ~ .
~ sequence, but if not it is skipped so that any called for notes .
~ can be read out in orderly note sequence regardless of how random-,~ ly they may be positioned in the array of all possible notes. The ~ speed of readout can be controlled at will. This readout controls ; 30 and effects arpeggiation.

: -The busses 30, 31, 32 are divided into octave sections by series diodes Sl and shunt diodes 53. For example, the C bus starts with the C2 switch 10, and proceeds via a resistance 50, and a series diode 51, conductively poled, to the C3 switch, which in turn proceeds similarly to the C4 switch, and so on. The anode of diode 51 is connected via a shunt diode 53, to a bus 54. Every series diode is provided with a shunt diode, all connected to the same bus 54. If bus 54 floats, the shunt diodes 53 are totally ineffective and the series diodes as Sl, are conductive, and all notes of the same nomenclature are then represented on bus 30, when they fall above the note actuaIly caIled forth.
However, if a note in the "3" octave is called for, the diode 51 acts to isolate the "2" octave gates, because of the polarity of ; diode 5i. Therefore, all notes of a given nomenclature, called l for by an actuated key, for all octaves above that key, are simul-¦ ; taneously gated on by the key, but no notes of that nomenclature in lower octaves are gated on.
~` If the cathodes of shunt diodes 53 are grounded, by ground-1, ing bus 54, at switch 12, no octaves are gated on which are i higher or lower than the octave being played in, since a series diode isolates the lowe,r octaves, and a shunt diode isolates the !: ~
higher octaves. However, a player can play a chord spanning two octaves, and all played notes will be heard together, either in the piano mode if that is called for, or sequentially in any of the remaining modes, "up only" or "up-down" as called for, by appropriate switches, hereinafter described.
It is evident that separate controls could have been pro-vided for each separate set of three shunt diodes 53, if desired, and also that a sequential readout could have been provided for each signal gate, if desired, instead of for each set of three.
The design actually selected presents a compromise between cost or complexity, and performance, which is justified by musical and economic realities.
Referring to Figure 2, 71 is a flip-flop or counter stage (of which there are twenty in the present embodiment of the inven-tion) which has two modes of operation, depending on the status of three key switches associated with the stage (four in the case of the twentieth flip-flop.) Three signal gates, shown in Figure I as 23, 24, 24a, are illustrated at 72. It is necessary that any of the three notes, on an OR basis, control the state of counter stage 71, so that any and every note called for be sounded, but it is also necessary that when a lower octave note is keyed, higher octave signal gates are actuated as well as the signal gate pertaining directly to the actuated key. Circuits for the latter purpose are illustrated in Figure 1.
Signal input9 to the tone gate 36 are derived from three adjacent notes, as C2, C2~, D2, and each set of three notes in the system requires a tone gate, except for the highest four notes, 20~ which utilize a single tone gate.
A positive voltage source is available at lead U, which is conveyed via any one or more of key switches 10, identified as Sl, S2, S3, to terminal 74, and thence to the collector of transistor Ql~ of flip-flop N, shown as 71. This transistor is nor~.ally on and Q2 of flip-flop 71 is normally off. If voltage is applied to collector of Ql' the flip-flop will act as a bistable flip-flop.
If none of the key switches is closed, transistor Ql has no col-lector supply and the stage acts as a monostable device with a time constant of about 30. mlcroseconds.
The trigger input ~ fllp-f~op871 is a short duty cycle . ;

rectangular wave applied at T, from the clock.
Before proceeding further with details of circuitry, reference is made to Figures 4 and 5 of the accompanying drawings where the logic of the present system is illustrated, in respect to control signals in Figure 4 and tone signals in Figure 5. KS
is a series of key switches #13 - ~73 of an electronic organ.
Discussing key switches #13, ~14, and #lS, each supplies gating voltage, as via a lead 100, to a three signal gate SG, (23, 24, 25a of Figure 1) pertaining to three keys, which sum and pass tone signal to tone gate TGl via a single lead (shown in Figure 5.) Twenty signal gates SGl - SG20 are illustrated to encompass sixty-one key switches, SG20 pertaining to the highest four key switches, ~-~ and SGl to SGl9 to three key switches each.
. , :
j The tone signal paths are illustrated in Figure 5. Each ' tone gate i~ a linear gate of known type and carries, without ; intermodulation, one, two, or three tone signaIs, according to which key or keys are actuated. In addition each signal gate, i, - ~ ~ , ~ SGl - SG20, controls signal gates an octave above itself, in ;, ~:
respect to notes of the same nomenclature, as indicated by leads 20 ~ 102 in Figure 4. So SGl primes SG5, which primes SGg, which primes SG13, etc. m e circuits required are illustrated in Figure 1 involving busses 30, 31, 32. Any key which is actuated thus can , ~, close the gates which serve to pass all notes of the same nomen-clature as the key- which is actuated, in higher octaves. Circuit details to this end are illustrated in Figure 1. The tone signals passed by the signal gates SGl - SG20 are passed to the tone gates NGl - NG20, respectively.

The outputs of the tone gates are tone signals which pass to summing amplifiers 105 (Fig. 5), each amplifier serving two tone gates. The tone gates are normally open (non-conductive) and ~ 1053490 are closed by signal on a lead 70 from terminal 0 of the associated counter stage (E`igure 2.) The sustain time of the tone gate is controlled by sustain circuit 107 (Figure 4) which is turned on whenever any associated key switch of KS is closed, in response to a note played detector 108 which senses the playing of any note as a voltage variation.
Whenever one of SGl - SG20 is operated by playing one or more of the notes of the gate a latch-in voltage is applied to the appertaining counter stage Cl - C20 via a lead 45, which trans-fers that stage from its normal configuration as a monostable flip-flop, which stays on for only a few microseconds when triggered, to a bistable flip-flop which must be reset or timed by a clock CL. me note played detector 108 supplies a varl~ty of signals , via lead 110, i.e., a 30. microsecond pulse to the first stage Cl to initiate a scan cycle o~ the counter, at lead 111, a +D.C.
voltage to an enable or start control circuit 112, which supplies voltage via lead 113 which enables the counter Cl to respond to ;; the pulse on lead 111. The latter so operates that once the : ~ :
counter starts it can complete its up sequence regardless of ;~ 20 whether or not a new key is depressed during the up sequence, in normal up arpeggio or s,trum mode. The start control 112 also serves to enable restart of a cycle of the counter, for example, if all c~ntrolling key switches are opened.
The time between the playing of notes is established by a clock CL, normally inoperative, but which is started into operation and terminated via +D.C. control signal on lead 115, the latter being supplied from lead 110. This ~D.C. signal is the same as is supplied to start control 112.

The counter Cl - C20 can count,up or down, i.e., it is 30. reversible, according to the charactleO of a control voltage supplied -^ ` 1053490 by up-down flip-flop 116. The bus 110 supplies a pulse to up-down flip-flop 116 when a note is played, to assure that it is in the up state, and will therefore cause the counter chain always to count up immediately after a key is depressed.
A manual switch 120 supplies signal from the last counter C20 of the chain, selectively, to a lead 121 or a lead 123, selectively. If to lead 121, a pulse is supplied to up-down flip-flop 116 from counter C20 which transfers the entlre counter chain into a downwardly counting chain, and at the same time trans-fers information to the start control 112 via lead 122 which will , , .
permit.-the next pulse from Cl, signifying termination of a down : count, to set the start control in a state whiFh allows the intro-duction o a new pulse rom lead 110 into the counter chain at , , Cl, thereby initiating a new up count sequence.
If switch 120 is in its down position an output pulse at ~ C20,~signallying that the counter chain Cl - C20 has completed an ,~ up sequence, proceeds via lead 123 to start control 112 and sets it forthwith in condition for a new sequence of up counts, start-~ ng at Cl.
'`~ 20 ` : Sustain control 107 supplies a sustain control signal via lead 125 to a common gate 126. This gate is triggered on via voltage on lead 127 connected to a common bus 105, wnich is supplied with a pulse as each note of gates NGl - NG20..is turned on by counter chain Cl - C20, via leads 127a.
~ The present system has five modes of operation, called ; for purpose of identification, (1) normal (2) strum (3) arpeggio up (4) arpeggio up and down (5) multi-note.
. In the normal mode no arpeggio is desired, but the instru-ment responds to each key as it is actuated. -25V is applied via `-` ` 1053490 switch 130 to lead 131, common to all the counters. This converts the counter stages to a mode in which they are essentially pulse amplifiers. There~ore, any note played transfers a gating pulse from a signal gate to a counter stage and thence to a tone gate, which transfers that note to one signal amplifier, say 105 (Figure 5~ for notes 13, 14, 15, and the note is sounded. Another output of each TG gate proceeds to lead 105 (Figure 4), which operates :
; common gate 126, whlch transmits notes which have passed through a tone color filter.
10The clock CL, when the switch 130 connects it to lead 131, applies a positive pulse to the counter stages and these then if bistable, are timed. The clock CL is normally inoperative, and , .
` starts operation in response to playing o a note, which causes D.C. to be applied to the clock CL via lead 115.
The strum mode is the same as the arpeggio-up mode, except that only notes actually played produce sounds, and higher octave notes are not sounded. It therefore corresponds with a limited range arpeggio.

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To illustrate what occurs we may assume that two notes are 20~ played simultaneously, one encompassed by three note gates SGl and the other by SG2. If both were encompassed by SGl, for example, they would sound together, and no strum effect would occur. But, if both SGl and SG2 are actuated, the note played detector applies a start pulse to Cl. Cl and C2 are latched into the bistable state via leads 45 from SGl and SG2, the clock CL is started, and the up-down flip-flop 116 is placed in the up mode. me stages Cl and C2 then operate in sequence under control of the clock and cause gates TGl and TG2 to pass tone signal in sequence. The remainder of the counter stages are not latched into the bistable state and therefore ignore the clock CL, operating as monostable circuits. The count then ripples up the chain very rapidly after passing Cl and C2 and on achieving stage C20, a pulse is passed via lead 123 to start control 112, which applies a count complete signal to counter stage Cl. Holding down the two notes thus does not cause a repeated strum. But if at least one of the played . . :
~; keys is released and pressed again, the note played detector 108 produces signals which cause the sequence to repeat, since the note played detector 108 detects depression of a ~ey whether or not other keys are then depressed.
~,~,",~,"
In the up-arpeggio mode,~operation is the same as for~
strum, except that each note played enables the gates SG of ~- ~ octavely related notes, higher in pitch. Actuating a D2 note iy~ key~, or example, renders conductive the D3, D4, D5, etc. gates, ~ along with the D2 gate, just as i the D3, D4, D5 keys had been , ",~
actuated.
; The C~l, C5, C9,~C13, etc. counter stages are then set into bistable state, and are read out in sequence under control of the;clock CL. The tempo for the latter is not affected by the ~`~-`20~ counter~;stages which are rippled through because ripple time is so~short relative to clock-on time.
For arpeggio up and down the output of C20, instead of re-establishing start control 112 in condition to receive a new note, resets the up-down flip-flop I16, which establishes all ` the counter stages Cl - C20 into the down counting mode. The start control 112 is now controlled by Cl via lead 135 in con-junction with the signal on lead 122, so that the 5tart control is prepared for a new start signal if one appears on lead 111, and the down count has been completed through Cl. However, if , a note is played while the arpeggio is moving down, a pulse via lead llO from note played detector 108 throws up-down flip-flop 116 into its up mode. A new pulse can still not be inserted at Cl, but the count now proceeds up, and any bistable stages cause notes to sound. Whenever a new note is played, up-down flip-flop 116 goes into up mode, if it is not already there.
The clock CL has a manual rate control 140. But that rate can be modified by movement of the expression pedal of an organ, by means of an expression control 141. The latter in-~, , .
creases clock rate as a function of loudness called for by theexpression pedal.
The start control 112 can operate in two states. It can, in one state, prevent Cl from accepting a further pulse, after an arpeggio has started, until control 112 has been reset by a pulse ;~ on lead 123 in the up arpeggio mode, or by a pulse on lead 135 in ~' ~; conjunction with information on lead 122 in the up-down arpeggio ' mode. In this state when an up arpeggio has been started it can-, ~:
not be modified until it has been completed. If in the up-down arpeggio mode, and in the down count condition, the actuation of a key will reverse the direction of the arpeggio, but will have ; no effect on Cl.
In the other state, the start control 112 does not prevent Cl from accepting additional pulses from the note played detector 108 via leader 110 and 111 of Figure 4. Thexefore each time a note is played a new start pulse is introduced into Cl and this pulse is free to proceed up the counter chain. Due to this con-dition of start control 112, multiple stages of the counter, which are in the bistable state due to the actuation of a key, can be read out simultaneously. The identities of the stages that are read out simultaneously are variable and under control of the operator by his actuation of additional keys during the counting sequence. Since each bistable stage that is read out sounds the note or notes present at the corresponding signal gate SG through the corresponding tone gate TG, multiple notes can be played and the combination of these notes controlled by the operator. This is called the multl-tone effect, since multiple notes can be heard simultaneously or plural arpeggios can be pro-ceeding simultaneously. Whether start control 112 will operate in the normal or thé multi-tone mode is determined by control 144.
In Figure 5 is illustrated the tone signal paths of the present system, The signal ~ates SGl - 8G~0 pass signals from the sources 13 - 72,;each gate handling three notes, or in effect constituting three gates with a single output. That single out-put for each of SGl - SG2~, (SG21 handles only signal 73 and its output is summed to SG20 output), is applied to its tone gate, - so that twenty tone gates TGl - TG20 are required.
Ten amplifiers 105 convey the outputs of the twenty tone gates to a distributed tone color filter DFI which is well known, per se, from which two ~roups of tone colored signals are taken, string tones on lead 147 and flute tones on lead 148.
The string tones proceed to two piano tone filters, #2 and #3, of diverse tonal characteristics, while the flute tones on lead 148 proceed to a third piano filter, #1. The outputs of piano filters #1, #2, #3 are summed at node 150, and lead via ta~
switches TB to volume control 151 and thence to the amplifiers 15 and loudspeakers 16 of the organ, shown in Figure 1.
The flute tones on lead 148 proceed to a harp filter 152 ~5 and a harpsichord filter 153. To the latter is also supplied string tone from lead 147, and a banjo filter 154 is likewise supplied. The output of the harp filter is supplied via lead 155 directly to node 150, and the output of piano filter #3 via common gate 126 to the output of guitar filter 156 and harp ~ilter 152. The guitar filter is supplied with the output of the harp filter. Common gate 126 supplies a pluck effect to the initial moments of a guitar or harp note. Common gate 126 is turned on with an output of any tone gate TGl - TG20, as evi-denced by lead 105 (Figure 4), and its sustain time is controlledfrom bus 125. The tone filtering system is per se well known, and orms no part o the present invention, and, accordingly, ~ ,;~.. ..
~ speciic circuit details are not supplied.
. ~,........................................................... .
Proceeding now to discuss circuit details for implementing the logic of Figure 4, in Figure 2, 200 is a source of voltage, .5 v., which is connected to three key switches Sl, S2, S3, in parallel. The gates 72 are all the same, so that only one will be i` ;~ described. All the gates derive signal inputs at 201, in the form , of square waves, positively going, and the outputs of the three 20 ~ gates are applied via a common lead 203 to a tone gate 36. The applied D.C. voltage proceeds, when Sl is closed, via diode 204 to charge a capacitor Cl via high reactance 206. Discharge of . ~ .
Cl is under control of the tone source, a square wave 207 of the prbper frequency for the pitch called for by the key switch Sl.
Cl therefore slowly charges while the square wave 207 blocks diode 208, and then discharges rapidly when diode 208 is unbiocked.
The resultant wave on lead 203 is 209.
Closure of switch Sl also supplies positive voltage via diode 210 and lead 211 to a gate of cor.esponding nomenclature, one octave higher in pitch, and so on through all such gates. ~:;

-1053490 `
For the D.C. voltage supplied by key switch Sl can be substituted a voltage arriving via lead 212 from a gate of the same nomencla-ture, but of one octave lower pltch.
In the strum or normal mode of playing it is desired that higher octaves not be primed when a note of a lower octave is plàyed. To defeat transfer of signal on lead 211, -4.5V can be supplied at W, which renders diode 213 conductive and shorts out lead 211. Any one or more of the three gates, herein denominated , :
; a signal gate, when energized via a key switch, as Sl, or via a -~10 lower octave key switch from a line 212, transfers D.C. voltage on lead 74 to a counter flip-flop 71 of counter chain 13, that voltage being applied to the collector o transistor Ql, having an emitter at -4.5V, and a base connected to lead 215 which proceeds to, selectively, clock CL or -25V., according to the position of switch ~ , 130, Figure 4. If the -2~V. supply is applied Ql is held cut off, which implies that the base of Q2 is supplied with the steady voltagé on lead 74, while a key of three note gate 72 is depressed and remains conductive, its emitter being at -4.5V. Incortiing leads to the typical stage 71 are 116a and 117a. With -25.V applied 20 via lead 215 the counter stage 71 is inoperative to count, and -this applies to aIl counter stages. But when a key switch is closed, the lead 74 applies a positive voltage to the base of Q2, which generates a drop in voltage at its collector, which in turn appears as a transient pulse at the base of transistor 220 of tone gate 36, transient because of coupling capacitor 221. Be-cause transistor 220 is PNP this pulse turns the transistor transiently on, and passes current into the diodes 222, 223 of linear gate 224, via 1. megohm resistances 225, 226, respectively.
The linear gate is pe~ se well known. It is normally non-conductive, 17 -`;
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and is rendered conductive as a function of bias current applied to the anodes of its two diodes 222, 223. When transistor 220 passes current capacitor Cn is charged positively, and immediately commences to discharge. Part of the discharge at least, taXes place via the gate and turns the gate on. There is also a dis-charge path through diode 227 to sustain bus 228. That bus is held at a voltage variable by adjusting slider 229 of potentio-meter 230. The terminal 231 of potentiometer 230 is supplied with ~ positive voltage from the note played detector (Fig. 3B.) terminal - 10 ~ Sl and the potentiometer 230 at its low voltage end is at -4.5V.
....
It follows that the -4.5V. biases the ga~te 224 off through diode 227, but when a note is played the voltage at point 229 rises.
The rate of discharge from Cn is thus modified according to the position of slider 229, which provides a discharge path in parallel with the gate 224. If the slider is at LO.V, for example, there is no by-pass and the gate has a long sustain, but if the voltage is at -4.5V. sustain is very short. The output of tone gate 224 may be one, two, or three notes, depending on which of Sl, S2, S3 -are closed, but since the gate is linear no intermodulation occurs.
-~20 ~ ~Clearly, in theory, the system could have been devised to utilize one, two, four or five ,signal gates per tone gate, the actual num-~ .
ber, three, being a compromise choice.
If the clock is connected to terminal T, the counter ispermitted to count and each stage acts as a bistable or mono-stable flip-flop depending on whether or not there is voltage applied to the stage on lead 74 via one, two or all of the key switches 51, 52-or 53. Referring to counter flip-flop 71 of .
Figure 2, the initial state of each stage (no keys activated) is Ql on and Q2 off. The iactuation of a key switch and resulting : 18 :

, application of volta~e to the collector o~ Ql does not change the state of the flip-flop but does provide the necessary supply to make the stage act as a bistable flip-flop. Each stage is read out by the application o~ a positive ripple pulse either on lead 117a or 116a which is coupled to the base of Q2, and saturates that transistor. This changes the state of this stage and provides a negative step at the collector of Q2 which is coupled to tran-sistor 220 in the tone gate and sounds the corresponding note.
The next positive clock pulse that appears at terminal T saturates ~- 10 Ql and changes the state of the flip-flop. This transition pro-vides a positive step at the collector of Q2 which appears at terminal G as a positive pulse and is connected to 117a of the preceding stage and 116a o the succeeding stage. Depending on the state o~ the up-down flip-10p, the succeeding or preceding stage is then provided with a positive ripple pulse which causes that stage to be read out or rippled through.
If there is no latch in voltage on lead 74, reception of a ripple pulse at the base of Q2 will saturate it only for the duration of that pulse, which is too short to activate the ~note gate transistor 220. Upon coming out of saturation this stage transmits a ripple pulse to the next counter stage. One of the leads 130, 131 may be connected to -4. 5v. If so ripple pulses ~ , are grounded by one of the diodes Dl, D2 and do not reach the base of Q2; thus the voltage condition of leads 130, 131 control the direction in which ripple pulses will progress, either up or down the counter. Essentially, each staye transmits ripple pulses both up and down, but one of these pulses is inhibited and the other not, to establish the direction of the count.

.;.
.. `d;~

When no keys are actuated there is no current flow through resistors 241 and 242 which hold Q10 (Figure ~B) off because its base and emitter are at the same voltage. U is a supply terminal for all key switches. If one of these is closed, current flows from terminal 240 through resistances 241, 242, to terminal U, lowering the voltage at the base of Q10, which then fires, passing 11.5V. to the sustain bus 231 (Figure 2). At the same time a negative pulse is applied to the base of transistor 242, forming part of a monostable flip-flop with transistor 243, which transmits a pulse on lead 244 via capacitor 245. This pulse is applied to lead 116a of counter stage 1 ~Figure 2), and starts a count. It is also required that the note played detector supply D.C. to the start control 112 and operate blas to the clock CL and a reset , pulse to the up-down flip-1Op 116 to assure that it is in the up state. The translstor 24Z supplies a pulse via lead 250 to the base of the transistor 251 of the up-down flip-flop, which resets the latter. me clock derives its D.C., so long as any key switch KS is closed, from terminal S (Figure 3B) of the note played detec-tor 108, via lead 2S4 to the base of transistor 255. The latter 20~ normally ha9 no voltage applied, and is cut off so that the clock cannot operate. When positive voltage is supplied to the base of transistor 255 of clock CL, that txansistor is biased on and the clock, consisting of a multivibrator, can proceed to oscillate.
Its timing or frequency is set by the value of resistance 257, which sets the bias for transistor 255. An alternate pedal con-trolled clock is illustrated in Figure 6.
The output of clock CL proceeds via amplifier 260 and lead 261 to the upper contact of switch S4. If the upper switch con-' tact is closed the output pulses proceed to lead 262, and thence 2 0 ` ;~

-~ 1053490 to all the counter stages. If the switch arm S4 is down -25V. is applied to lead 262 via lead 263 and the counter does not count.
When no keys are actuated the start control 112 is forced into the start state in which transistor 281 is of and 270 is on.
This state is insured because, with no keys actuated, lead 259 is at -4 . 5V., which prevents transistor 281 from being on. The state of the up-down flip-flop is not forced under these conditions, and therefore it can be either in the up or down count state.
When one or more keys are actuated the note played detector , ~provides collector supply voltage to transistor 270 of the start control via lead 259 but does not change the state of the start control. Therefore, the collector of transistor 281 is high, which provides a reverse bias on diode Dl o counter stage 1 t71 in Figure 3A). This permits the introduction of the positive pulse from the note played detector on lead 254 which starts the counter counting. At the same time, a positive pulse is fed from the note played detector 108 via lead 250 to the base of transis-tor 251 of the up-down flip-flop 116, to set it in the up count state. Now that these two controls are set the counter begins to count up.
The purpose of the start control 112 is to prevent more than ;~ one pulse from being introduced into the counter from the note ~ played detector while a count sequence is in progress. This is ~ ~ ::: ` :: :
accomplished by feeding the output of counter stage 1 to the start control flip-flop via lead 273. This pulse is directed vla diodes 283 and 2333A and leads 271 and 271A. m ese leads are connected to the down control bus and up control bus, respectively, such that when in the up count state, the output of the counter stage 1 is directed to the b~-se of transistor 281. This saturates that .. . .

transistor and changes the state of the start control 112 to keep transistor 281 saturated, which places a forward bias on diode Dl oP counter stage 1. Diode Dl shunts any lnput pulse on lead 244 to -4.5V. and presents it from operating counter stage 1. If in the strum or the up arpeggio mode, the output of counter stage 20 is ed via lead 275 and switch S5 to the base of transistor 270 which saturates that transistor and changes the state of the start control flip-flop so that it will allow a new pulse to be introduced into the counter chain. This is done because stage 20 represents the end of an up count sequence. If, however, the ; device is in the up-down mode, S5 is open and the output of stage 20 is not fed to the base of transistor 270. Instead the second output from stage 1, that occurring while the up-down flip-flop is in the down count state, is directed to the base of transistor 270 via lead 273 and diodes 283 and 283A, and leads 271 and 271A.
This changes the state of the start control flip-flop so that it will permit the introduction of a new pulse into the counter chain, which is necessary because the second output of counter stage 1 indicates the end of an up-down count sequence.
~20 In the multi-tone mode, switch 280 is opened, allowing ::
the emitter of transmitter 281 to float, which prevents lead 282 dropping its potential, so that ripple pulses can be introduced at any time. This implies that any closure of a key will start a new count sequence. If the switch 280 is open and the system in the arpeggio up only mode, pulses can be introduced at any time at stage #1, and will travel up the counter, regardless of other pulses then in process o proceeding along the counter. If the sys-tem is in the up-down mode and pulses are introduced on the way down, the count direction will be reversed simultaneously with their introduction.

lOS3490 It is not illustrated, but if there were sèparate up and down counters, new pulses could be introduced into each at any time, producing simultaneous up and down arpeggios. In the present system the counter must be either proceeding up or proceeding down, and any key closure occurring while the counter is counting down reverses the direction of travel.
While the simple clock of Figure 3B is suitable generally, an alternative more sophisticated clock is provided~in Figure 6, which has its rate controlled in two modes or by two complementary controls.
Qll to Q14 represents an astable multivibrator of conven-tional character per se, having its last stage Q14 coupled to its irst 5tage Qll via a capacitor C22. The frequency of the oscilla-tor i9 determined by the current injected into the capacitor 22, which is controlled by transistor Ql9. The latter operates as a constant current source, i.e., as if it possessed sufficiently high Lnternal resistance that current flow into the capacitor C22 is constant, regardless of voltage across C22. When transistor Q14 turns on, the negative step at its emitter is coupled via capacitor-22 to the base of transistor Qll which turns that transistor off by driving its base to approximately -9V. Transistor Qll cannot turn on again until capacitor 22 charges up to approximately -4V.
T is charging period is controlled by the current from constant current source Ql9 and therefore this source controls the frequency of the clock. The negative step at the collector of transistor Qll when the transistor turns on, is coupled via transistor Q12 and capacitor Cl to the hase of transistor Q13 which turns that transistor and transistor Q14 off. The period of this section of the cycle (Q13 and Q14) is not variable and is determined by the 23 ``, .. . ..

lOS3490 -time constant of Cl and R3`. When`the base of transistor Q13 recovers from the negative pulse from transistor Qll, Q13 turns on which turns on Q14 and couples a negative step from the emitter o Q14 to the base of Qll, which is the beginning of another cycle.
The transistors Q15, Q16 constitute a pulse amplifier and wave shaping circuit which lS conventional per se and therefore is not described in detail.
When a note is played +ll.SV. is applied to terminal 290, '~ ~ , ' ' ' .
rom note played detector 108. A current path is then provided through lead 291, variable resistance 292, diode 293, resistance R21, the emitter of transistor Ql9, the colLector of Ql9, capaci-tor C22, the emitter of Q14, and back to -4.5V. When the capaci-tor is to be charged, Q14 is conductive, so that e~ectively the charge on the capacitor 22 is referenced to -4.5V.

, , The current delivered by transistor Ql9 is I = 11.5 V - VB - VBE - VD
. R21 ~ R28 , ~ , In the equation, VB is the voltage at the base of Q9, VBE is the voltage drop base to emitter of transistor Ql9, VD the drop in diode 293 and R21, R28 the values of the resistances in series wlth transistor Ql9, and all are constant. The voltage at the emitter of Ql9 will follow the voltage at the base of Ql9, less about .5V., so that by controlling the base voltage the current : `
flow into C22 can be controlled and will remain constant regard-less of the instantaneous voltage on the capacitor, and further this current can be controlled by varying circuit resistance, i.e., at R28.
A transistor Q20 has its collector connected to the collector of Ql9, its base maintained at low voltage via R22, R23, and its collector coupled by capacitor C24 to the terminal -` ~053490 290, which is supplied with ~11.5V, when and only when a note is played. Since the emitter of Q20 is connected to -4.5V, and the base is connected via R23 to -50V, if there is no voltage on lead 290 (no keys played) transistor Q20 turns on thereby holding the base of Qll at -4.5V. This stops the clock when no keys are played and assures the same starting conditions on the clock.
Capacitor C24 provides a positive pulse at the base of Qll when the first key is played to sync the clock to the playing of the first key or keys.
10 - A variable voltage divider is provided in terms of Rl9 and Q18, the latter having its bias controlled by R17, R18, act-ing as a voltage divider. Current flow into the base of Q18 determines its resistance so that it is, effectively, a variable resistance controlled by Q17.~ The latter has its emitter connected to a known constant voltage, its collector connected directly to the base of Q18, and its base connected to a source of voltage controlled by the expression shoe of the organ containing the present system.
If ES is open the sole control for the current supplied by Ql9 to capacitor C22 is variation of the value of R28, manually controlled. If ES is closed, a bucking voltage is applied to the cathode of D3 as follows. An NPN transistor Q21 is connected across a voltage source. A potentiometer 292 is connected from its collector to its emitter, and the slider of the potentiometer 292 is connected to the base of the transistor, which is collector loaded. Current flow into the collector is then a function of slider position, which is controlled by expression pedal EP. The voltage conveyed from the collector of Q21, via lead 294 is variably positive and therefore controls the voltage , at the base of Ql7 and hence its collector voltage. Accordingly, the position of the expression pedal EP controls the resistance of Q18, which in turn controls the bias of Ql9 and hence current flow into C22.
As the expression pedal is pressed downward, the loudness of the organ increases. Similarly, the voltage at the base of Q21 increases and current flow out of Ql9 increases, increasing arpeggio rate.
~ The pedal of the organ thus becomes a useful~and convenient :~10 device for changing rate of arpeggiation as the arpeggio proceeds, up or down, and the expedient is muslcally sound because soft music is appropriately associated with slow arpeggio, and vice ;~ versa. Of course,~other devices may be substituted for the pedal.
For example, a knee operated potentiometer may be employed. The crucial point is to provide a voltage controlled clock such that it may be controlled while the hands are occupied with playing i~,.
of the organ, and use of the pedal provides a particularly pleasing effect, musically.
It is desirable to prevent the top note in an arpeggio from being played twice, when the present system is in the up-down mode. If the top note played pertains to counter stage C20, there is no problem, since only up-going pulses affect this stage and therefore there can be no repetition of the top note. But, for example, if the top note pertains to counter stage #19, the system will play that top note, ripple through to stage ~20 in negligible time, and back to #l9. Therefore the top notes will play twice with negligible time interval. This distorts the tempo of the arpeggio.
To solve the problem of double top note pulses in the up-down mode, the keyswitches which pertain to counter 20 (and note #73), provide a voltage on lead 300 via isolating resistances R12, Rl5, R18, R21 (Figure 7). Those key switches pertaining to counter stages #19 and #20 provide voltage at lead 301, and those key switches pertaining to counter stages ~18 and ~19 and #20 to lead 302, all via appropriate ones of isolating resistances Rl - R21, inclusive.
There are three transistor gates, Q31, Q32, and Q33, which are of NPN type, and have their collectors commonly connected to ' D.C., the down control voltage from the up-down flip-~lop 16 (see Figure 3B), via load resistances~R22, R24, R26. The emitters of the three transistors are commonly connected directly to -4.5V.
and the collectors respéctively connected via resistances R23, , R25 and R27 to the bases of the Ql, stages of the C17, C18 and Cl9 ~counter stages, labelled TI in Figure 2, which illustrates one typical counter stage.
The device is inactive while the arpeggio is proceeding up,~ since D.C. is~not avallable.~ When the down control voltage D.C. is applied, it is routed to the TI leads of counter stages C17, Cl8, Cl9. However, a gate of SG18 will be routed via Rl, R2 or R3 to turn on Q31, which removes the down control voltage ; from TIl7, so that the stage TIl7 can be free to operate normally in the down arpeggio. Similarly, gate voltage from signal gate SGl9 will turn on Q31 and Q32, removing the down control voltages from TI17 and TI18, and a gate voltage of SG20 will remove down control voltage from terminals TI17, TIl8, TIl9, by turning on Q31, Q32, Q33. Thus, the down control voltage appears only on the counter corresponding to the highest note played, regardless of which of the ~17, 18, 19 or 20 tone gates is involved.

10534~0 The transistors Q31, Q32, Q33, when open or unfired, per-mit the D.C. voltage to proceed to the TI bases thereby pxeventing corresponding notes from sounding, but when saturated by a voltage from S518, SZlg or SG20, they remove the control from the TI lead,~
whereupon the correspondlng counters can respond to the clock and enable production of sound.
It follows that if and only if a #20 gate is keyed on, will counter stages #17, ~18, #19 be able to sound a note during down ~arpeggio. If a ~19 gate is the highest keyed on, gates ~17 and #18 will be able to sound in down arpeggio, but not~#l9, and if gate #18 is the highest keyed on, stage ~17 will be~able to sound in down arpeggio but not #18.
The down control voltage-appears at the counters only for the highest note played, only on the way down. For a note in SG20, no controls are needed, and i SGl9 and SG20 are energized simul-;~ taneously, SGl9 will sound on the way down. But if, for example,SGl9 is the highest note played, it must be silent on the way down and sound only on the way up.~
Operation of the present system i5 summarized as follows.
20~ The up-down counter necessary to produce sequential pulsing con-sists of twenty counter flip-flops, illustrated in Figure 2. Each of these flip-flops has two modes of operation, which depend on the stage of the three (or four in the case of stage 20) organ key switches associated with that stage. If one or all of these key switches are closed (or in the case of arpeggio any key associated with a lower note that is octavely related to the notes associated with the stage under consideration) the flip-flop acts as a bistable flip-flop with initial state of Ql on, Q2 off. If none.
of these keys is depressed the flip-flops act as monostable flip-: 28 .. ;.

.

~ -~` 1053490 flops with an operating time of appro~imately 30. microseconds.
In either case the initial condition of the flip-flop is Ql on and Q2 off. In strum and arpeggio modes of operation, but not normal mode, the trigger input T is a 10 volt square wave with short duty cycle. Each stage has two inputs which provide the means to switch out of the initial state: one is used for the up count and one is used for the down count. These inputs require a positive pulse, and have means (diodes Dl and D2) to cancel any attempt to switch the state of the flip-flop through either or both inputs.
These stages are interconnected, as shown on Figure 3, with the -output of each stage (Gn for the Nth stage) feeding to the up count inp~t of the next stage (Un+l) and also to the down count input of the preceding stage~(Dn-l). Stage 1 recelves the first pulse at its up count input (Ul) from the note played detector, as shown in Figure 3. The clock is also synchronized With this note played detector so that the first clock pulse occurs simul-taneously with the playing of a note and the switching of stage 1. An "up-down flip-flop" is also set in the up count mode from the note played detector. When the output of stage 1 (Gl) has a positive transient it switches stage 2 via the up count input (U2). This switching of stage 2 will take place either at the next clock pulse if stage 1 has been energized (that is if the conditions were met to make stage 1 act as a bistable flip-flop) and in a much shorter time (the operating time of the monostable) if stage 1 has not been energized. This sequence is repeated until the counter reaches and switches stage 20 at which time the counting stops if the system is in the strum or up arpeggio mode.
If it is in the up-down arpeggio mode G20 is connected to the down count input of stage 19 (Dl9) and to the "up-down flip-flop"

.. . .

- - `` 1053490 which changes the state of this flip-flop to the down count state, and conditions the counter for down count. The pulse introduced into stage 19 by stage 20 is now free to proceed down the chain in the same manner as the up count pulse-proceeded up.
The start control (Figure 3) determines when a start pulse can be applied to the up count input of stage 1. This control has four inputs, two of which are driven by Gl and each controlled by the "up-down flip-flop." If we are in the up count operation a positive pulse at Gl will set the start control so that no new pulse ;~10 can be introduced. If we are in the down count mode a positive ~ pulse from Gl will set the start control so that new pulses can ,~ be introduced. If we are in the up arpeggio or strum, stage #20 ;~s ~ is connected to the start control BO that after the up-down counter ha5 counted up through stage ~20, another pulse can be introduced into stage 1. When in the up down arpeggio mode the ~s,;
connection between stage #20 and the start control is broken so ~that no new pulses will be introduced into stage 1 until the down count is complete. In the multi-tone mode, the start control is essentially disabled so that a new pulse can be introducéd at 20 ~ any time, In the normal mode switch Sl disables the up down flip-flop through diode D3 and places the start control in a state so that no pulses can be introduced into stage 1. It therefore disables the up down counter. Now any key played will provide , current through IN of the counter flip-flop which will saturate Q2 and provide a negative pulse at ON. This current is not diverted through Ql because the trigger input has now been switched and the trigger is now a negative voltage which will prevent Ql from latching in an on position. A gating pulse is therefore passed by the counter stage operating as an amplifier.

Claims (36)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In an electronic organ, a multi-stage counter, a plurality of tone signal sources, a separate key for each of said sources, means for differentially controlling diverse stages of said counter in diverse manners in response to actuation of said keys, means responsive to actuation of any one of said keys for initiating a count of said counter, and means for enabling only selected ones of said tone sources in sequence according to the manners of controlling of said stages.

2. The combination according to claim 1, wherein each of the stages of said counter is arranged and adapted to be selectively monostable and bistable, and wherein the manners of controlling said stages are that said stages are each selectively rendered bistable and monostable, and wherein the time constants of the stages while monostable are of the order of less than a millisecond, and wherein said counter is assynchronous.

3. In an electronic organ, an assynchronous multi-stage counter, each of the stages of said counter being selectively bistable and monostable and when monostable having a time constant of the order of less than 100 µsec, a plurality of normally inoperative tone sources allocated respectively to said stages, a plurality of key switches, means responsive to actuation of any of said key switches for initiating an up count of said counter, and means responsive only to the bistable stages of said counter for rendering operative tone sources allocated to said bistable stages.

4. In an electronic organ, a multi-stage counter, a plurality of normally disabled tone sources allocated respectively to the stages of said counter, a plurality of key switches, means for initiating an up count of said counter, means responsive to the count of said counter as said counter counts up for enabling said tone sources in sequence, and means for selectively rendering inoperative to produce tone signals selected ones of said stages such that only those tone sources are enabled which are not operatively associated with an actuated key switch.

5. The combination according to claim 4, wherein in response to actuation of one or more of said key switches all stages not allocated to the actuated key switches are rendered inoperative to produce tone signals.

6. The combination according to claim 5, wherein said operatively disabled stages are arranged to count for a time inadequate to enable tone sources and the enabled stages for a time adequate to enable said tone sources to produce audible tone when enabled.

7. The combination according to claim 6, wherein said disabled stages are monostable and the enabled stages are bistable.

8. In an electronic organ, an up-down multi-stage counter, a plurality of key switches, means responsive to simultaneous actuation of any of said key switches for initiating an up count of said counter, means responsive to completion of said up count for initiating a down count of said counter, means allocating said key switches to the stages of said counter, respectively, said stages of said counter having counts each of selectively two diverse characteristics, means responsive to the actuated key switches for selecting the one of the two characteristics which shall pertain to any stage of said counter allocated to said key switches, a plurality of normally disabled tone sources, and means responsive to the counts of said counter of one of said characteristics only as said counter counts up and down for selectively and sequentially enabling said tone sources.

9. In an electronic organ of claim 8, for sounding an up and then a down sequence of all notes of nomenclature corresponding with the nomenclature of said at least one actuated key switch other than notes of octave lower than called for by said at least one actuated key switch, means responsive to actuation of another key switch while said sequence subsists for reversing the direction of said sequence in said counter.

10. In an electronic organ, a plurality of tone signal sources, a plurality of key switches, an electronic commutator arranged to scan said tone signal sources in sequence, and means responsive to simultaneous actuations of plural ones of said key switches for determining which of said tone signal sources shall be converted to tone signals in an arpeggio sequence by said electronic commutator, said commutator being a multi-stage counter.

11. The combination according to claim 10, wherein said electronic commutator is a multi-stage digital counter, and means for initiating a count of said counter in response to said actuations of said switches.

12. The combination according to claim 10, wherein said multi-stage counter is a reversible digital counter.

13. The combination according to claim 12, wherein is included means responsive to completion of an up count of said counter for reversing the direction of count of said counter.

14. The combination according to claim 11, wherein said commutator is a multi-stage digital counter having stages corresponding with said key switches and means responsive to said actuations for converting those stages of said counter which correspond with the actuated key switches to bistable stages, said stages being normally monostable.

15. In an electronic organ having a keyboard, means responsive to playing of keys of said keyboard for sounding an arpeggio of notes both corresponding with and octavely related to said keys, said means including an electronic multi-stage digital counter, said counter including stages connected in cascade and corresponding with said keys, said stages being normally inoperative to sound said notes and means responsive to playing of said keys for rendering operative to sound said notes those stages corresponding with the played keys and octavely related keys.

16. The combination according to claim 15, wherein said key-board for sounding an arpeggio of notes sounds an up arpeggiation.

17. The combination according to claim 15, wherein said keyboard for sounding an arpeggio of notes sounds an up followed by a down arpeggiation.

18. The combination according to claim 17, wherein is included means for at will reversing the direction of said down arpeggiation.

19. An electronic organ having a keyboard, comprising an electronic counter including plural stages, said stages being normally monostable devices, organ key operated means for converting selected ones of said stages to bistable stages, means for controlling the timings of the resets of said bistable stages, a plurality of tone signal sources, and means responsive to said bistable stages only for converting said tone signal sources to tones.

20. The combination according to claim 19, wherein said counter is assynchronous.

21. The combination according to claim 20, wherein is provided means responsive to actuation of any of said organ keys for initiating a count of said counter.

22. The combination according to claim 21, wherein said counter is reversible.

23. The combination according to claim 22, wherein is included means for reversing the count of said counter on com-pletion of an up count of said counter.

24. The combination according to claim 23, wherein is included means for reversing a down count of said counter in response to actuation of any of said keys during a down count.

25. In an electronic organ, a multi-stage counter, a plurality of tone signal sources, a separate key for each of said sources, means for differentially controlling diverse stages of said counter in diverse manners in response to actuation of said keys, means responsive to actuation of any one of said keys for initiating a count of said counter, and means for enabling only selected ones of said tone sources in sequence according to the manners of controlling of said stages, wherein is provided means for deleting the topmost of said tone signals only during reverse direction count of said counter.

26. In an electronic organ, an array of keys, an array of tone signal sources each corresponding with one of said keys, a digital counter comprising a cascaded array of flip-flops,means rendering each of said flip-flops selectively normally operable in a time of the order of 30 microseconds and long term operable, means establishing a correspondence between said keys and the stages of said counters, a load circuit including a loudspeaker, means responsive to actuated ones of said keys for rendering the corresponding ones of said stages of said counter long term operable, and means for transferring said tone signals to said load circuit only in response to long term operated flip-flops.

27. The combination according to claim 26, wherein is provided means for resetting said counter in response to completion of a total count of said counter.

28. The combination according to claim 26, wherein said counter is a reversible up-down counter and wherein is provided means responsive to completion of a total count of said counter for reversing the count of said counter and completing a down count of said counter.

29. The combination according to claim 28, wherein is further included means for at will reversing the count of said counter during a down count of said counter.

30. The combination according to claim 29, wherein said means for at will reversing is means responsive to actuation of any of said keys.

31. The combination according to claim 26, wherein is included means for at will disabling said counter and for transferring all said tone signals to said load circuit concurrently.

32. The combination according to claim 26, wherein the corresponding ones of said stages include only tone signals of the same octaves as said keys.

33. The combination according to claim 26, wherein the corresponding ones of said stages include tone signals of octaves higher than the octaves of said keys.

34. A musical instrument comprising:
(a) generator means for producing a series of signals corresponding to a plurality of musical tones;
(b) a keyboard;
(c) a set of key-operable switches operable by the keys of said keyboard;
(d) a series of control gates for selectively inter-connecting the key-operable switches in circuit with said generator means for producing tones in response to operation of said gates;
(e) scanning means for sequentially scanning and operating said control gates;
(f) control means associated with said scanning means at operated ones of said key operable switches for successively holding the scanning operation of said scanning means from proceeding and for operating said control gates;
and (g) means to restart the scanning operation of said scanning means

35. Apparatus according to claim 34, including means connected with said control means for operating successive ones of said control gates with substantially no delay between the period during which one such gate is operated and the period in which the next successive gate is operated, rel-ative to the duration of operation of each gate, whereby an arpeggio is produced with substantially no delay between successive tones of said arpeggio.

36. Appartus according to claim 34, including mode selector means connected with said scanning means for causing said scanning means to scan in one direction during a first period and to scan in the opposite direction during a second period, and disable means connected with said scanning means for inhibiting said scanning means from holding at the first of said operated switches which is scanned during said second period.