US 3902395 A
A musical instrument has electrically conductive strings and a fingerboard with an array of fingerpads each serving as an electrical contact with which each of the strings are selectively connected as they are manually adjusted in length in selecting musical notes to be played when the string is vibrated. For each string there is a separate pick-up device for indicating when the string is vibrating. Circuitry including time-division multiplexing circuitry and gating circuitry controlled by the pick-up devices provide electrical signals representing notes related either directly or preferably harmonically to those played on the instrument.
Claims available in
Description (OCR text may contain errors)
United States Patent 1 1 1111 3,902,395 Avant Sept. 2, 1975  STRINGED MUSICAL INSTRUNIENT WITH 3,697,661 10/1972 Deutsch 84/ 1.01
ELECTRONIC TINIE DIVSION 3,786,167 l/1974 Borell et a1. 84/l.16
MULTIPLEXING CIRCUITRY Primary ExaminerRichard B. Wilkinson  IIIVCIIIOI'Z William L. Avant, P.O. BOX 1268, Assistant Examiner stanley J witkowski Blg Bear 92315 Attorney, Agent, or FirmChristie, Parker & Hale  Filed: Oct. 11, 1973 21 Appl. No.2 405,666  ABSTRACT A musical instrument has electrically conductive strings and a fingerboard with an array of fingerpads  84/l'16; 8471-01; 84/DIG 30 each serving as an electrical contact with which each  Int. Cl G10h l/; GlOh 5/00 of the Strings are Selectively connected as they are  held of Search 84/101, 1316' 30 manually adjusted in length in selecting musical notes to be played when the string is vibrated. For each  References cued string there is a separate pick-up device for indicating UNITED TAT PA E when the string is vibrating. Circuitry including time- 3,196,729 7/1965 Burns et a1 84/D1G. 30 division multiplexing Circuitry and g g Circuitry 3,482,028 12/1969 Cox et a1. 84/1.16 controlled by the pick-up devices provide electrical 3,482,029 12/1969 Sines 84/1.16 signals representing notes related either directly or 3,530,226 9/ 1970 wheeler 84/ preferably harmonically to those played on the instru- 3,530,227 9 1970 Wheeler et a1. 84/1.l6 men. 3,610,799 /1971 Watson 84/1.01 3,673,304 6/1972 Dudas 84/1.01 8 Claims, 7 Drawing Figures Jan-21 I 322 1 6 ZO'Z -1 :64
2721 r 227;? 17/266511 k fi A: 1
68 TO 27-5 rxnouqll 27-20 T/Mr DIV/S ION 01 UL 'r/ FLEX DIGITAL s/qA/AL EDI STRINGED MUSICAL INSTRUlVIENT WITH ELECTRONIC TINIE DIVISION MULTIPLEXING CIRCUITRY BACKGROUND OF THE INVENTION This invention relates to musical instruments of the type adapted to provide electrical signals representing notes selected for playing.
Various patents teach the idea of providing a musical instrument, such as a guitar, with electrical circuitry adapted to supply control signals to effect remote playing of another instrument such as an electrically controlled organ. In a typical prior art approach, such as that disclosed in US Pat. No. 3,482,028, the fingerboard of the guitar has arranged on it a matrix of electrical switch contacts. Such a matrix comprises a row for each string, there usually being six such rows in a guitar; and it comprises a column for each fret, there usually being 19 frets although more are sometimes provided. The strings of the guitar are electrically conductive and, in combination with the contacts, form a plurality of switches, one such switch for each fretstring combination. In playing the instrument, of course, the strings are manually depressed against the frets so as to adjust their effective length to select desired notes. As the strings are so depressed, switch contacts are closed, and circuitry responsive thereto develops signals indicating what note or notes have been selected.
As was mentioned, it is common to have six strings and at least 19 frets. Thus, there are at least 114 fretstring combinations and, accordingly, in the abovedescribed approach, there are a corresponding 1 l4 switch contacts. Since the switch contacts must be electrically isolated from each other and since there are such a large number of them, they must each be quite small in practice. Also, each must be precisely mechanically aligned in the proper position on the fingerboard; otherwise, a switch closure might not be effected when the musician frets a string. Significant too is a problem with this approach that arises from the manner in which many musicians prefer to play a guitar. That is, many guitarists, by habit or design, will sway the strings while playing. By this is meant that the strings are depressed sideways as well as downwardly. When this is done, a fretted string can completely miss the appropriate contact, or, possibly worse, it can, when severely swayed, be connected to an adjacent contact.
SUMMARY OF THE INVENTION The musical instrument of this invention comprises a plurality of electrically conductive strings that extend parallel to each other along the length of a fingerboard, and preferably is embodied in a fretted guitar. The fingerboard has mounted on it a plurality of electrically conductive fingerpads. Each fingerpad is positioned at a respective one of a plurality of spaced-apart locations where the strings are depressed to adjust their effective length. Significantly, in contrast to prior art approaches, each fingerpad extends transversely beneath the parallel strings so that any string can be depressed into contact with it. That is, instead of a multi-row, multi-column swiching matrix of many small switches, there is provided a simpler mechanical construction to define a switching arrangement. Moreoever, the switching arrangement is not subject to the abovedescribed problems that have arisen incident to swaying. In the preferred embodiment, a plurality of pick-up elements are each disposed adjacent a respective string and each generates a control signal in response to vibration of the respective string. Circuitry including time-division multiplexing circuitry and gating circuitry provide electrical signals representing notes related to those played on the instrument.
The time-division multiplexing circuitry includes circuit means that cooperate with the switching arrangement to produce a cyclical time-division multiplex digital signal that at separate sequential intervals within each cycle indicates the effective length of a respective one of the strings, such effective length being related of course to a note selected for playing. Incident to the use of this multiplex technique, any one particular binary format carried in parallel by the same set of wires represents at different points in time each of a plurality of selected notes. A significant advantage of this is that fewer switching-signal-carrying wires need be connected to the instrument than in prior art approaches. For example, in the above-described prior art guitar there are l 14 switching-signal wires, each individually connected to a separate one of the l 14 contacts. In an embodiment of this invention, only five switchingsignal wires are used; yet, as much information is carried by them.
Preferably, there is included within the circuitry an arrangement for computing representations of harmony notes. This arrangement is preferably used in combination with an electronic guitar. In use, the musician plays the electronic guitar in a normal manner, the speaker system for the electronic guitar reproducing directly the notes played by the guitarist and at the same time, by remote control, another instrument accompanies him in harmony.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top view of a guitar, which is the preferred embodiment of this invention;
FIG. 2 is a block diagram of circuitry used in this preferred embodiment;
FIGS. 3A and 3B are a block diagram and a group of timing diagrams respectively, showing the preferred arrangement and operation of a control signal developing part of the multiplexing circuitry used in this invention;
FIG. 4 is a schematic and block diagram showing the preferred arrangement of a switching arrangement Within the multiplexing circuitry;
FIG. 5 is a block diagram of a representative one of a plurality of latch elements within the multiplexing circuitry; and
FIG. 6 is a block diagram of a harmony note computer included within the preferred embodiment.
DETAILED DESCRIPTION FIG. 1 shows a guitar 5, which is the preferred embodiment of the musical instrument of this invention. The guitar has an elongated fingerboard 7 extending from a body 9. A plurality of elongated strings I0 (hereinafter sometimes collectively referred to as the string bus 10) span the guitar, each string being secured near one of its ends by a string-holding mechanism 12 on the body and having its opposite end secured to a respective one of a plurality of tuning pegs 14 on the fingerboard. The strings are each electrically conductive whereas the mechanical supports for them are not, so that the strings are electrically isolated from each other. Thus, the conventional mechanical elements of the guitar such as the bridge 16 on the body and the plurality of frets 18 on the fingerboard are each insulated.
A plurality of electrically conductive fingerpads 20 are arranged on the fingerboard. Each fingerpad is positioned at a respective one of a plurality of spacedapart locations between adjacent frets. It is at the frets that the guitarist depresses the strings to adjust the effective length, thereby to select the notes to be played when the strings are plucked.
Each fingerpad extends transversely across the board so that any string can be depressed into contact with it. The electrically conductive fingerpads and the electrically conductive strings thus cooperate to form a switching arrangement, which is discussed in more detail below.
Each fingerpad is individually connected to a separate one of a plurality of switching-signal carrying wires that are collectively referred to as fingerpad bus 22. There is mounted on the body an encoder board 25 which is a circuit board supporting a plurality of encoding gating arrangements 27 (FIG. 2) that receive switching signals carried by the fingerpad bus.
A plurality of pickup elements 30 are each disposed on the body adjacent a respective string. Each of these pickup elements provides for generating a control signal in response to vibration of a respective string, incident to that string being plucked.
Preferably, as shown, a separate plurality of pickup elements 33 are provided. These pickup devices are used in connection with a conventional electronic guitar amplifier and speaker arrangement (not shown). An electrical connector 35 is provided for interconnecting these pickup elements and the amplifier.
A separate connector 37 on the body is provided for electrically interconnecting the guitar to other circuitry which is shown in block diagram form in FIG. 2. Also mounted on the body are a plurality of manual control switches 40, 41 and 42 whose function will be described below.
FIG. 2 shows an overall block diagram of circuitry that provides electrical output signals representing musical notes. A commutator 45 is connected by the string bus to the switching arrangement. As shown in FIG. 3A, the commutator includes a clock 50 that produces a clocking signal CP. Clocking signal C? has the form of a pulse train, preferably at an ultrasonic frequency. A conventional cyclical counter 52 counts the clock pulses. Preferably, counter 52 cyclically counts through six states, Sl-S6 (see FIG. 3B). A plurality of decoders 55-1 through 55-6 each decode a separate one of the states of the counter. Each of the decoders, under gating control of the clocking signal, provides a separate one of a plurality of signals sbl-sb6.
The operation of the counter is illustrated in the wave form diagrams of FIG. 3B. As shown, the clocking signal CP switches back and forth between logical 0 (low) and logical 1 (high) levels. Under trigger control of the clocking signal, the counter cyclically counts through states Sl-S6, changing its state on each logical 1 to logical 0 transition in the clocking signal. The signal sbl, produced by the decoder 55-1, assumes a logical 0 value during each part of the cycle wherein the clocking signal has a logical 0 value and the counter is in state S1. At all other times during the cycle, the signal sbl has a logical 1 value. The signals sb2sb6, produced respectively by decoders 55-2 through 55-6 have similar timing diagrams, each being at the logical 0 value during corresponding portions of sequential states occurring within the cycle.
The signals sbl-sb6, as indicated in FIG. 4, are applied to the strings 10-1 to l0-6, respectively. (In the block diagram of FIG. 2, these strings are shown collectively as string bus 10.) Beneath the strings, there are 21 fingerpads 20-1 through 2021 of which 20-1, 20-2, and 20-21 are shown by way of example.
FIG. 4 also shows respective wires 22-1, 22-2, and 22-21 of the fingerpad bus 22. The wires of the fingerpad bus individually connect the fingerpads to respective ones of the plurality of the encoding gating arrangements 27-1 through 27-21 of which 27-1, 27-2, and 27-21 are shown by way of example. Each encoding gating arrangement includes one or more (up to five) diodes. In gating arrangement 27-1 for example,
there is one diode 60 having its cathode connected to wire 22-1. The output of encoding gating arrangements are connected to the wires forming an encoded data bus 63. These wires are individually shown in FIG. 4 as 63-1 through 63-5. A plurality of inverter circuits are-r through 64-5 each have an input connected to a separate one of the wires of bus 63 and an output connected to a separate one of the wires of encoded data bus 65.
In operation, there is developed in the data bus 65 a cyclical time-division multiplex signal EDl that at separate sequential intervals within each cycle indicates the effective length of one of the strings. By way of specific example, consider the guitarist operation when the guitarist simultaneously frets string 10-1 into contact with fingerpad 20-1 and string 10-6 into contact with finger 20-2. In this specific example, the, ED]. signal has the following pattern. During state S1 of the counter while signal sbl is low, wire 63-1 is held low (i.e., a logical 0) by virtue of the flow path from string 10-1 through fingerpad 20-1, and diode 60. During this state, none of the other wires 63-2 through 631-5 are held low. Accordingly, at this time, the encoding of signal EDI, at the output of the inverters, is expressed as 00001. During states S2 through S5 of the cycle, none of the wires 63-1 through 63-5 is held low. The encoding of the signal EDl at each of these times is expressed as 00000. During state S6 of the cycle, while signal sb6 is held low, wire 63-2 is held low by virtue of the flow path from string 10-6 through fingerpad 20-2, and a diode 68. Accordingly, at this time, the encoding of signal EDI at the output of the inverters is expressed as 00010.
Preferably, the guitar strings are tuned in the conventional manner. That is, strings 10-1 through 10-6 are tuned such that they play the notes E, B, G, D, A, and E respectively when plucked while open (i.e., not fretted).
A truth table for the signal EDl as it relates to the length of the sampled string is given below in Table I. In Table I, the effective length of the string is expressed in terms of which, if any, of the fingerpads is in contact with the string through fretting.
TABLE 1 Fingerpad to which sampled string is fretted Coding of signal ED] TABLE l-Continued Fingerpad to which sampled string is fretted Coding of signal EDI Preferably, as indicated in FIG. 2, a harmony computer 70 (to be described below with reference to FIG. 6) is connected by data bus 65 and a data bus 73 between the encoding arrangement and a decommutator 75. The output of the harmony computer is a digital signal ED2, and as with that of the gating arrangements, it is a time-division multiplex digital signal.
The decommutator comprises six memory cells 75-1 through 75-6 of which 75-1 and 756 are shown by way of example in FIG. 2. To illustrate their construction an arbitrary one, 75-i, is shown by way of example in FIG. 5. Each of the memory cells corresponds to a respective one of the strings. Each of the memory cells is cyclically loaded so that each provides a stored indication (SI-l-SI-6) related to what the effective length of its corresponding string was at the time the memory cell was loaded. Within each memory cell, there are five flip-flops preferably of the D type. Thus, each flipflop has a D input, a clock input (CL), and an output Q. This type of flip-flop has the characteristic that the logical level applied to its D input is transferred to its Q output upon a predetermined transition in logical level in its clock input. As shown in FIG. 5, the clock inputs of the five flip-flops are directly connected together and in turn are connected to receive as a clocking signal one of the signals sb. (In FIG. 2, a single dashed line is shown to represent this coupling between the commutator and the decommutator.)
Each memory cell is connected by a bus to a decoding arrangement 80 (FIG. 2). Decoding gating arrangement 80 is responsive to the stored indications provided by the memory cells and also to control signals derived from the pickup element to provide on an output bus 90 a multi-bit digital signal ED3 representing notes related to those being played on the instrument. The output bus comprises a plurality of wires (not individually shown), one for each separate note. The digital signal ED3 is encoded such that a logical l is carried by each wire corresponding to a note to be indicated and a logical 0 is carried by the other wires of the bus 90.
There are well known circuits available to implement the function of the decoding gating arrangement. In the preferred embodiment, integrated circuit chips sold by National Semiconductor Corporation under the designation 7441 are used. Each of these chips has its input connected to a selected one of the memory cells. The chips are of the well-known wired-or characteristic and accordingly their output can be directly connected together. The outputs of different chips that indicate the same note preferably are so connected together. The control signals from the transducer channels are applied to the V inputs of these circuits so that they can provide a logical 1 output only when a corresponding string has been plucked. In an advantageous feature, any particular note can be held as long as desired. To this end, in the preferred embodiment the memory switch 40 is provided. As indicated in FIG. 2, the logical OR function of the output of the memory switch 40 and the individual control signals from the transducer channels, and each is applied to the respective V inputs of these circuits. Thus, with the memory switch 40 closed, notes are indicated simply as a result of fretting without actual plucking.
In the preferred embodiment in which there is provided a harmony computer the truth table given in Table II defines the logical function of the decoding arrangement 80.
TABLE II Musical Note Indicated on Output Bus Coding of (With separate reference to each of the stored Signal ED2 indications Sl-l through SL6) s1-1 S12 $10 $14 s1-5 Sl- 00000 D#2 B 2 F#2 c#1 c#o D#0 00001 E2 132 02 D1 A1 E0 00010 F3 c2 c#2 D#1 E 1 Fl 00011 1=#3 c#2 A2 E1 Bl 1=#1 00100 03 D2 M2 F2 c1 01 00101 G#3 D#2 B2 F#2 c#1 o#1 00110 A3 E2 c2 02 D1 A1 00111 B113 F3 c#2 c#2 D#1 8 1 01000 B3 1-"#3 D2 A2 El B1 01001 c3 c3 D#2 B52 F2 01 01010 c#3 o#3 E2 132 F#2 c#1 01011 D3 A3 F3 c2 02 D1 01100 D#3 ED3 E#3 c#2 c#2 D#l 01101 E3 B3 03 D2 A2 E1 01110 F4 c3 G#3 D#2 13 2 F2 01111 F#4 c#3 A3 E2 B2 1=#2 10000 04 D3 BM F3 c2 02 10001 o#4 D#3 B3 F#3 c#2 c#2 10010 A4 E3 c3 03 D2 A2 10011 A#4 F4 c#3 c#a D#2 E 2 10100 B94 F#4 D3 A3 E2 B2 10101 B4 G4 D#3 A#3 F2 c2 10110 01 o#4 E3 B0 3 F#2 c#2 10111 c#4 A#s 1=3 B3 02 D2 By way of further explanation of Table II, consider the following. The guitarist plays the musical note F1 by fretting string 10-6 into contact with fingerpad 20-1 and simultaneously plucking that string. This fretting of string 10-6 causes during state S1 of the cycle the signal EDI to assume the binary code 00001. As will be explained below, through selective setting of the harmony computer, the signal ED2 can differ from or equal the signal EDI. When it is desired to have a direct relationship between the musical notes indicated on output bus 90 and the notes played by the guitarist, the binary number 1 is added to the signal EDl to form the signal ED2. Thus, as shown in Table II, the binary code 00010 (i.e., 00001 plus 1) for the signal ED2 is decoded to indicate the note Fl. On the other hand, it is possible to have an indirect relationship. For example, to indicate a flat note, the signal EDI is not modified. Then when the guitarist plays the note Fl there will be indicated the note E1. Alternatively, to indicate a sharp note the signal EDI is modified by the addition of two. Then when the guitarist plays the note F1 there will be indicated the note F 1.
A unique and highly advantageous preferred feature is provided by the harmony computer 70, shown in more detail in FIG. 6. The function of the harmony computer is to convert signal ED1 into signal ED2 such that the notes represented by signal ED2 are related in a desired harmonic relationship with the notes actually selected by the guitarist. Accordingly, the guitarist can use the harmony computer so that while he plays the electronic guitar in his normal manner he is accompanied by an electric organ, for example, which plays harmonically related notes. For example, the relation between each of selected notes played by the guitar and corresponding notes played by the organ can be a harmonic third relationship. That is, the notes differ by three half-tones on the musical scale. And, during the same tune, other notes can differ by four half-tones for example.
As part of its overall function, the harmony computer provides for detecting what note (relative to a musical octave) has been selected by fretting. To this end, the bus 65 is connected to adder circuitry 100. Also connected to the input of adder circuitry 100 are adder logic gates 103, 104, 105 and 106. When string 10-2 is being sampled by the counter (i.e., signal sb-2 of FIGS. 3A, 3B and 5 is low), gate 103 in response provides a binary number 01 l I. When string -3 is being sampled, gate 104 in response provides binary number 0011. When string 10-4 is being sampled, gate 105 in response provides a binary number 1010. And, when string 10-5 is being sampled, gate 106 in response provides the binary number 0101.
As a result of this arrangement, the sum produced by adder circuitry 100, will, irrespective of which String is being sampled, uniquely indicate which note within an octave was selected. Table III, given below, gives the coding of this sum in relationship to the notes selected by the guitarist. (Table III is based upon the guitar strings being tuned in a conventional manner.)
A decoder, which peferably is an SN74l54 also sold by National Semiconductor Corporation, decodes the sum. The decoder 105 has 12 output wires that are used here. These are wires 107-1 through 107-12 and each is individually connected to one of a plurality of switches 110-1 through 110-12 (not all shown). Each of these switches is a single-pole, triple-throw switch. Each of these switches is associated with a separate one of the twelve notes within an octave.
A logical gating arrangement 115 and a logical gating arrangement 1 17 each has a control input connected to interconnected contacts of the switches 110. Each of these gating arrangements has its output connected to one input of adder circuitry 120. The other input for adder circuitry 120 is connected to the outputs of logical gating arrangement 121 and 123 which in turn are controlled by the switches 41 and 42 located on the body of the guitar. The output of adder circuitry 120 is connected to one input of adder circuitry 130 which has its other input connected to bus 65.
In mathematical terms, the harmony computer provides a means for effecting a selected one of a plurality of mappings between the signal EDI and ED2. In one selected mapping, the signal ED2 is a direct copy of the signal ED1. To do this, the various switches are set as follows. Each of the switches -1 through 110-12 is set in it center position so that, irrespective of what note is played, neither gate nor gate 117 is activated. Also switches 40 and 41 are each opened. With the switches so set, the output of adder circuitry 120 is a constant (i.e., 0). Thus adder circuitry adds 0 to signal ED]. and the sum it produces (i.e., signal ED2) is a direct copy.
in another selected mapping, the signal EDZ has a binary value of three greater than the binary value of signal ED1 irrespective of which note is played. To do this, the switches are set substantially the same as they are for the direct copy but the switch 41 is closed. With switch 41 being closed, gating arrangement 121 provides the binary number 3 to the adder circuitry 130.
A multiplicity of other mappings are achieved by selective switching of the switches 1 10-1 through 100-12. As a representative example, switch 110-1, which is associated with the note E, can be switched to connect its corresponding decoder output to gate 115. Thus each time any one of the E notes (there being more than one E note because of multiple octaves) is selected, gate 115 is activated and it causes the binary number one to be added to the other input of adder circuitry 120. On the other hand, switch 110-1 can be switched to connect its corresponding decoder output to gate 117. In this case, each time any one of the E notes is played, gate 117 is activated and it causes the binary number two to be added.
Consider now as a representative example the following operation. In this example, the guitarist desires to play the electronic guitar in a conventional manner and be accompanied in a predetermined harmonic relationship by a slave instrument such as an electrically controlled organ or an electronic music synthesizer. The desired harmonic relationship is such that each time he plays any one of a first plurality of notes (within any octave) on the guitar, the organ will play a note three half-tones higher in the musical scale. This plurality in this particular example comprises the notes A, B b B, c, c# ,D, M ,F, F# and G# On the other hand, he desires to play flat with respect to G and to play sharp with respect to E. Thus when he plays A, for example, which is in the first plurality, the organ plays C. When he plays G on the guitar, the organ plays the flat note F (i.e. flat relative to harmonic third). When he plays E on the guitar, the organ plays the sharp note G (i.e., sharp relative to harmonic third). To implement this, the switches ar set as follows. Switch 40 is closed to activate gating arrangement 121. Each of the switches within the switching bank 110 which correspond to the first plurality are switched to the natural position so as to activate gating arrangement 115 to cause the binary numer 1 to be added to the binary number 3 derived from gating arrangement 121. The switch within switching bank 1 10 which corresponds to the note G is switched to the flat position (i.e., centered) so that neither gating arrangement 115 or 117 is activated when this note is played on the guitar. The switch within switching bank 1 10 which corresponds to the note E is switched to the sharp position so as to activate gating arrangement 117 each time this note is played on the guitar. When activated, gating arrange ment 117 causes the binary number 2 to be added to the binary number 3 derived from gating arrangement 121.
In terms of the coded signals, when the guitarist plays the note E by plucking string 10-6 while it is open, the signal EDI as shown in Table l is coded as 00000. Since E is being played sharp, adder circuitry 120 forms the binary sum 0101 (i.e., the decimal number 5). In turn, adder circuitry 130 adds 00000 and 010i and yields the sum 00101, which as shown in Table llll corresponds to the note G# 2 (see column SL6 corresponding to string 10-6).
The switch 42 and the logical gating arrangement 123 provide substantially the same function as those described above. The difference in operation relates to the provision of playing a harmonic fifth. That is, the arrangement 123 provides for adding binary 0101 in contrast to arrangement 121 providing for adding binary 001 1.
What is claimed is:
1. In a stringed musical instrument of the type adapted to provide electrical signals representing notes selected for playing, the combination comprising: an elongated fingerboard;
a plurality of electrically conductive fingerpads each being mounted on the fingerboard at a respective one of a plurality of longitudinally spaced-apart locations;
a plurality of electrically conductive strings;
means for mounting the strings at fixed points so that the strings extend longitudinally adjacent the fingerboard;
each fingerpad extending transversely across the fin gerboard so that any string can be depressed into electrical contact with it; and
circuit means electrically connected to the fingerpads and the strings for producing a time-varying, parallelby-bit encoded digital signal that, when a manually selected string is depressed into electrical contact with a manually selected fingerpad, identifies the manually selected string and fingerpad.
2. A musical instrument comprising: an elongated fingerboard;
a plurality of electrically conductive strings oriented to be parallel to each other and to extend longitudinally adjacent the fingerboard, each string having an adjustable effective length that is defined between a fixed first point thereof and a selectable second point thereof, the effective length of a string being manually adjusted in use by depressing the strings at a selected second point to select a note to be played when the string is vibrated;
a plurality of electrically conductive fingerpads each being mounted on the fingerboard at a respective one of longitudinally spaced-apart locations where the strings are depressed to adjust their effective length, each fingerpad extending transversely across the fingerboard so that any string can be depressed into contact with it;
circuit means electrically connected to the fingerpads and the strings for producing a cyclical time-division multiplex digital signal that at separate sequential intervais within each cycle indicates the effective length of a respective one of the strings;
a plurality of memory cells respectively corresponding to the plurality of strings in that there is a separate memory cell for each string;
means responsive to the multiplex signal for cyclically loading the memory cells so that each provides a stored indication related to what the effective length of its corresponding string was at the time the memory cell was loaded;
a plurality of pick-up elements each disposed adjacent a respective string and each for generating a control signal in response to vibration of the respective string; and
an output bus comprising a signal transmission lead for each note playable on the instrument; and
gating means responsive to the stored indications provided by the memory cells and the control signals generated by the pick-up elements for providing to the output bus a multi-bit digital signal representing notes related to those being played on the instrument.
3. The musical instrument of claim 2 wherein said circuit means includes a plurality of encoding gating arrangements each having an input coupled to a separate fingerpad, a bus for carrying the multiplex digital signal, and wherein each encoding gating arrangement has an output coupled to the bus and gating circuit means that is activated by the switching contact between the fingerpad to which it is coupled and a string in electrical contact therewith to apply a coded multibit digital signal to the bus.
4. The musical instrument of claim 3 wherein said circuit means includes a commutator providing a plurality of sampling signals, each sampling signal being applied to a separate one of the strings and being coupled to the encoding gating arrangements through switching action of the strings and fingerpads.
5. The musical instrument of claim 4 wherein each memory cel comprises a plurality of latch circuits each having a clocking input, the clocking inputs of each memory cell being responsive to a respective one of the sampling signals.
6. The musical instrument of claim 2 wherein the memory cell loading means includes a harmony computer adapted to selectively modify the multiplex signal so that each memory cell upon being loaded stores an indication of a musical note bearing a desired harmonic relationship with respect to the effective length of the corresponding string.
7. The musical instrument of claim 6 wherein the harmony computer includes a separate manually settable switch for each of a plurality of musical notes, the harmony computer modifying the multiplex signal in accordance with the settings of the manually settable switches.
8. The musical instrument of claim 7 wherein the harmony computer includes adder circuit means for forming the binary sum of the multiplex signal and a binary number related to the setting of the manually settable