US3619468A

US3619468A - Stringed musical instrument with piezoelectric transducer providing gate control and music signals

Info

Publication number: US3619468A
Application number: US16819A
Authority: US
Inventors: Chauncey R Evans
Original assignee: Columbia Broadcasting System Inc
Current assignee: CBS Broadcasting Inc; Fender Musical Instruments Corp
Priority date: 1970-03-05
Filing date: 1970-03-05
Publication date: 1971-11-09
Anticipated expiration: 1988-11-09

Abstract

A method of creating a wide variety of player-initiated musical effects, which comprises employing a piezoelectric transducer in contact with the string of a guitar or similar plucked musical instrument, and thereby deriving from the string a control pulse upon each release of the string by the pick or fingers of the musician. The control pulse is utilized to control various gating and other means to create numerous rhythm, tonal and special effects. The apparatus comprises a string and associated piezoelectric transducer, in combination with an impedance changer for creating a very high output impedance for the transducer. Pulse separator and amplifier means are provided to separate the control pulse from the tone which is generated upon plucking of the string. Various monostable, bistable, shaper and gate means are provided to generate the desired tonal, rhythm and other effects.

Description

United States Patent 72] Inventor Chauncey R. Evans Costa Mesa, Calif.

[21] Appl. No. 16,819

[22] Filed Mar. 5, 1970 [45] Patented Nov. 9, 1971 [73] Assignee Columbia Broadcasting Systems, Inc.

New York, N.Y.

I54] STRING ED MUSICAL INSTRUMENT WITH PIEZOELECTRIC TRANSDUCER PROVIDING GATE CONTROL AND MUSIC SIGNALS 31 Claims, 5 Drawing Figs.

[52] U.S.Cl 84/1.I6, 84/1.03, 84/l.13, 84/1.24,84/D1G. 11 [51] lnt.Cl Gl0h3/00, GlOh H02 [50] Field of Search 84/ 1.03, 1.13, 1.16, 1.24, 1.25, 1.26, DIG. l1,DlG. 12, D16. 30

[56] References Cited UNITED STATES PATENTS 3,217,079 11/1965 Murrell 84/1.16 3,223,771 12/1965 Hopping 84/l.26 Re.26, 533 3/1969 Cookerly et al. 84/1.16

Primary Examiner-David X. Sliney Assistant Examiner-Stanley J. Witkowski Attorney-Gausewitz, Carr & Rothenberg ABSTRACT: A method of creating a wide variety of playerinitiated musical effects, which comprises employing a piezoelectric transducer in contact with the string of a guitar or similar plucked musical instrument, and thereby deriving from the string a control pulse upon each release of the string by the pick or fingers of the musician. The control pulse is utilized to control various gating and other means to create numerous rhythm, tonal and special effects. The apparatus comprises a string and associated piezoelectric transducer, in combination with an impedance changer for creating a very high output impedance for the transducer. Pulse separator and amplifier means are provided to separate the control pulse from the tone which is generated upon plucking of the string. Various monostable, bistable, shaper and gate means are provided to generate the desired tonal, rhythm and other effects.

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3 ,4 TOPA/EVS' STRINGED MUSICAL INSTRUMENT WITH PIEZOELECTRIC TRANSDUCER PROVIDING GATE CONTROL AND MUSIC SIGNALS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the field of musical instruments which are plucked by the fingers or by a hand-held pick, and which are associated with mechanical-electrical transducer means and amplifier-loudspeaker means.

2. Description of the Prior Art It has become common, in association with electrical musical instruments such as electric guitars, to provide rhythm circuits adapted to simulate various instruments, etc., so that the guitarist and his audience may feel that more than one instrument is present. Reference is made, for example to U.S. Pat. Nos. 3,146,290, 3,383,452 and Re. 26,521. The apparatus for producing such rhythm efi'ects has a major defect, however, in that the guitarist cannot continuously vary the tempo at which the rhythm effects are being created. Thus, the guitarist initially sets a knob on the rhythm-creating apparatus in order to adjust the tempo, but the tempo (once determined) remains constant throughout the entire piece. This may be equated to the guitarists getting on a merry-go-round and staying there. He cannot change the tempo unless he stops playing and resets the knob.

It has been proposed to provide electrically conductive picks for plucked instruments, and to employ circuit means for creating various effects in response to touching of such electrically conductive picks to the strings. Reference is made, for example, to U.S. Pat. No. 3,290,425. This, however, has the serious disadvantage that the pick must be electrically conductive and must be connected to a wire, with consequent added circuitry, nuisance, etc. It is not satisfactory, in such devices, to pluck the strings with the fingers only.

The indicated U.S. Pat. No. 3,290,425, and also U.S. Pat. No. 3,116,357, provide various control or gate circuits responsive to the picking or to a separate electromagnetic pickup.

It is known in the field of electric organs to create control signals in response to pressing of the organ key, for example by means of a switch operated by the key. Also, various percussion circuits, etc., are common in organs as disclosed (for example) in U.S. Pat. No. 3,160,694.

To the best of the knowledge of applicant, it has not previously been known in the field of plucked musical instruments to employ the same mechanical-electrical transducer which senses the string vibrations for the purpose of creating control pulses when, and only when, the pick or finger of the guitarist releases the string. Any pick employed with the present guitar need not be electrically conductive, and the strings may be plucked by the fingers instead of by a pick. No special frets, no additional wiring of the instrument, and no additional transducers are required. With the present invention, a guitarist playing a guitar of the type employing piezoelectric transducers may have control over the rhythm, tonal and other effects throughout the entire piece, and need no longer remain at the rhythm which was determined by the setting of the knob before initiation of playing. In addition, and very importantly, the present invention permits simulation of a banjo, for example.

SUMMARY OF THE INVENTION The invention comprises a method of creating player-controlled rhythm and other effects by providing a piezoelectric transducer in association with the string of a guitar or the like, employing such transducer to generate a control pulse when the string is released by the pick or finger of the guitarist, and rising such control pulse to determine the speed or tempo of rhythm-creating means, gating means, etc. Alternatively, the control pulse is used to cut ofi the sound a short time period after each release, thus simulating a banjo. The method further comprises feeding the control pulse from the piezoelectric transducer into an impedance changer having a very high input impedance, whereby to aid in separation of the control pulse from the remainder of the wave generated by vibration of the string. The method additionally comprises providing rhythm-creating circuitry which is initiated by operation of the control pulse and at repeated predetermined times, whereby the musician can change tempo at the end of any one of such times.

The apparatus of the invention includes a guitar string in combination with a piezoelectric transducer, an impedance changer having a very high input impedance and into which the transducer output is fed, a pulse separator and amplifier to separate the control pulse from the wave generated in response to continued vibration of the string, and gating and rhythm-creating means controlled by the control pulse. The last-named means includes a bistable circuit and a series of monostable circuits, to provide predetermined repeated rhythm effects which are initiated by a.control pulse at periodic intervals throughout each musical rendition. Shaper means are provided to determine the envelope of the wave which passes through the gating means to the amplifier and loudspeaker means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram, primarily in block form, illustrating one form of the method and apparatus of the invention;

FIG. 2 is a wiring diagram illustrating the impedance changer, and the pulse separator and amplifier circuit, which are shown at the upper portion of FIG. 1;

FIG. 3 is a schematic side elevational view illustrating a guitar string and the associated piezoelectric transducer and bridge means;

FIG. 4 is an illustration of the voltage wave which is present at a point between the impedance changer and the pulse separator and amplifier circuit; and

FIG. 5 illustrates the voltage waveform at the output of the pulse separator and amplifier.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring first to FIG. 3, a guitar body and/or neck is represented schematically at I0, having connected thereto at 11 and I2 the ends of a string 13 adapted to be plucked by the guitarist, either with a hand-held pick or with the fingers. A bridge 14 is provided adjacent one end 12 of the string, and is conventionally referred to as the nut. A second bridge 15 is provided adjacent the other end 11 of the string. The bridge 15 is composed of a base 16 on which is disposed a piezoelectric transducer 17. The transducer 17 supports the string 13 and is thus compressed in varying degrees depending upon the condition of the string.

Transducer 17 may be of various types but is preferably ceramic, being formed (for example) of barium titanate or lead zirconate.

The arrangement shown in FIG. 3 is conventional, as piezoelectric pickups (mechanical-electrical transducers) have been used in association with guitars and the like. It is a major feature of the present invention that the conventional arrangement illustrated in FIG. 3 is employed to create the control and rhythm efiects indicated above and hereinafter in this specification.

Referring next to FIG. 1, the transducer 17 is illustrated as being connected through an impedance changer 18 with a pulse separator and amplifier 19. These elements I8 and 19 will now be described in detail and in connection with FIG. 2.

As shown in FIG. 2, one side of transducer 17 is grounded at 21. The other side of the transducer is connected through a lead 22 to the base of a Darlington connection 23. which constitutes one very effective form of impedance changer 18. The Darlington connection has a very high input impedance and a low output impedance, being described (for example) on page 15 of the Handbook of Basic Transistor Circuits and Measurements," John Wiley & Sons, Inc., Semiconductor Electronics Education Committee, Volume 7. Also, reference is made to the silicon monolithic Darlington amplifiers manufactured by General Electric Company under its Nos. D16Pl, DI6P2, DI6P3 and DI6P4.

The Darlington connection 23, and other circuitry illustrated in FIG. 2, are biased from a positive lead 25 and a negative lead 26, the latter being grounded at 27. For example, positive lead 25 may be supplied from the positive terminal of a battery 28 the negative tenninal of which is grounded at 29.

The collectors in Darlington connection 23 are connected through a lead 31 to positive lead 25, whereas the emitter of the Darlington is connected through an emitter load resistor 32 to negative lead 26.

The above-indicated lead 22 from transducer 17 is connected through a very high resistor 33 to the junction between two series-related and much smaller resistors 34 and 35. Such series-related resistors are connected between the positive and

negative leads

25 and 26.

The various resistors determine the bias of the Darlington connection 23. The very high (for example, 10 megohms) resistor 33 forces the signal present in lead 22 to pass through the Darlington instead of being grounded through the lowervalue (for example, l kilohms) resistor 35. Thus, the Darlington connection 23 is caused to effect a high-impedance loading of the piezoelectric or ceramic transducer (pickup) 17, the Darlington acting as an impedance transformer or impedance changer. The purpose of this very high impedance which loads the transducer 17 is to cause a welldefined separation between what will be termed a control pulse" and the music," as next described in connection with FIG. 4.

Referring to FIG. 4, there is illustrated the voltage which results at the output of Darlington connection 23 (impedance changer 18) in response to two successive pluckings or pickings of the string 13 (FIG. 3) associated with the piezoelectric transducer 17. Two control pulses" 37 are shown in FIG. 4, each of such pulses resulting from (and immediately following) the release of the string 13 by the pick or finger of the musician. Also shown in FIG. 4 are the ensuing music" wave portions 38 which follow the respective control pulses 37.

Of particular importance is the fact that, especially when the piezoelectric transducer feeds into a very high-impedance load as in the present circuit, the control pulses 37 project major distances on one side of the horizontal or X-axis, whereas the music portions 38 of the wave are largely disposed near the axis or on the other side thereof. It is therefore possible, by using circuitry such as that described hereinafter relative to the pulse separator and amplifier circuit I9, to separate the control pulses 37 from the music portions 38, and to use such control pulses 37 to perform various functions as stated below.

If the load into which the transducer 17 feeds were very much lower, for example if the resistor 33 were only I or 2 megohms instead of megohrns, the control pulses would be much less prominent and would be less readily separable from the remaining portions 38 of the wave. It is for this reason that the load into which the piezoelectric transducer feeds (namely, the impedance changer 18) is made extremely high, preferably much higher than the high-impedance loads into which piezoelectric transducers normally feed.

Proceeding next to a description of the pulse separator and amplifier circuit 19, to which the output of the Darlington connection 23 (impedance changer I8) is supplied via a coupling capacitor 39, this includes an NPN transistor 41. The emitter transistor 41 is connected through an emitter resistor 42 to negative lead 26, and the collector is connected through a collector load resistor 43 to positive lead 25. The base of transistor 41 connects to capacitor 39, and is also connected through resistors 44 and 45 to positive and

negative leads

25 and 26, respectively. A gain-determining network, comprising a series-related resistor 46 and capacitor 47, is connected in parallel with resistor 42 between the emitter of transistor 41 and ground lead 26. Such network increases the gain to the transistor 41 without adversely affecting the bias thereof. The bias of the amplifier formed by transistor 41 and associated elements should be such as to prevent clipping of the control pulses 37 (FIG. 4).

The output of the amplifier, namely, the collector of transistor 41, connects to a coupling capacitor 48 and thus to a discriminating or clipping circuit adapted to transmit the control pulses 37 effectively while substantially blocking or eliminating the music portions 38 of the wave. Such circuit includes diodes 50 and 51 and an NPN transistor 52, the latter preferably being biased in such manner that it will discriminate against any remaining portions of the music wave 38.

Stated more specifically, the capacitor 48 is connected through a lead 53 to diode 51, and such diode in turn is connected through a series-related resistor 54 and capacitor 55 to the base of transistor 52. The diode 50 is connected in parallel with a resistor 56 between lead 53 and lead 26. An additional resistor, numbered 57, is connected between lead 26 and the junction between diode 51 and resistor 54.

Diode 50 is oriented in such manner that it will tend to pass to ground the music portions 38 of the wave (FIG. 4). The

resistors

56 and 57 are sufficiently high, for example kilohms, that the control pulses 37 will not be attenuated (passed to ground) in any major degree. Diode SI is so oriented that it tends to block the music portions 38 (FIG. 4) while passing effectively the control pulses 37.

The orientation of diodes 50 and 51 is correlated to the type and orientation of the piezoelectric transducer 17 with which the circuit is associated. In the illustrated circuit, it is assumed that transducer 17 is such that the control pulse portions 37 of the wave passed through coupling capacitor 39 are positive, as shown in FIG. 4. Such positive control pulses 37 are inverted by transistor 41 and are therefore negative at lead 53. The negative control pulses do not tend to pass through the diode 50 since the anode of such diode is remote from negative lead 26. correspondingly, such negative pulses are not blocked by diode 51 since lead 53 is connected to the cathode of such diode. If the polarity of the pickup 17 were reversed, each of diodes S0 and 51 would also be reversed.

The transistor 52 forms part of a second amplifier which is connected generally as is the first-described amplifier. Thus, the collector of transistor 52 is connected through a collector resistor 58 to positive lead 25, and the emitter of such amplifier is connected through a resistor 59 to negative lead 26. Series-related resistor 60 and capacitor 6! connect the emitter of transistor 52 to ground lead 26. Resistors 62 and 63 extend, respectively, from the base of transistor 52 to positive lead 25 and to ground. The series-related resistor and capacitor 60 and 61 serve, as do

elements

46 and 47, to change the gain of the associated amplifier without affecting the bias.

The output at pulse separator and amplifier circuit I9 is an amplified control pulse 37, as shown in FIG. 5. Such pulse is substantially free of the music wave portions, but it is to be understood that some small parts of the music wave portions may be tolerated if they are not able to start or affect the operation of the monostable circuit 70 mentioned hereinafter.

In addition to (or in place of) circuit 19, the peak portions of control pulses 37 may be separated from music 38 by a peak follower circuit. One such circuit is shown by FIG. 654 on page of the Handbook of Basic Transistor Circuits and Measurements," cited above.

Referring again to FIG. 1, the amplified control pulse 37 (FIG. 5) is delivered through a coupling capacitor 68 and resistor 69 to a monostable (one-shot) multivibrator 70. Such monostable generates a clean, uniform-value output pulse, of uniform duration, upon each actuation by a pulse 37 from pulse separator circuit 19.

The output of the monostable multivibrator 70 is connnected trough a lead 71 to the input or trigger terminal of a bistable multivibrator (flip-flop) 73. One output of the bistable multivibrator 73 is connected through a lead 74 to any desired number of series-related monostable (one-shot) multivibrators 75, 76, 77, etc. One output of the end one of the monostables, number 77 in the illustrated form of the invention, is connected through a clear line 78 to the clear terminal of the bistable 73.

The remaining output terminals of the

respective circuits

73, 75, 76 and 77 are connected through switches 79-82, respectively, to a lead 84 which is connected to the inputs of two (or more) shaper

circuits

85 and 87. The outputs of

such circuits

85 and 87 are connected through switches 89 and 88, respectively, to control terminals of a dual gate circuit 90.

The music generated by the piezoelectric transducer 17 is transmitted directly through a lead 91 (FIGS. 1 and 2) to the input of dual gate 90. The output of such gate is connected through a power amplifier 93 to'a loudspeaker 94.

The

monostable multivibrators

70, 75, 76 and 77 may be of conventional construction, and each incorporates means to determine the time delay which elapses between reception of an input or trigger pulse and transmission of an output pulse. However, in the case of monostable 70 no such time delay need be provided, because such monostable is normally set to deliver an output pulse immediately upon reception of the input or trigger pulse 37.

Bistable multivibrator 73 may also be of conventional construction, and delivers output pulses to lead 74 and to switch 79 immediately upon reception of an input pulse from the monostable 70 through lead 71. The two shapers 8S and 87 are also of conventional construction, and deliver envelopecontrol waves which are determined by the characteristics of the particular circuit. For example, shaper circuit 85 may deliver a waveform such as that indicated at 96, and which is characterized by a relatively steep rise followed by a slowdeclining ramp. Conversely, shaper circuit 87 may deliver one or more relatively steep and short pulses as indicated at 97.

The dual gate 90 is so constructed that the music passed therethrough from lead 91 to amplifier 93 is envelope controlled in accordance with one or both of the

waveforms

96, 97, etc., as. desired. This, for example, when switch 89 is closed the volume of the sound transmitted through gate 90 will be loud at the initial portion of wave 96 and progressively softer toward the end portions thereof. If there is no envelope signal at either gating terminal, no signal may pass through the gate from lead 91 to amplifier 93. One form of dual gate 90 which may be employed is a MOS Dual Keyer Gate with Snub Inputs, manufactured by Motorola Semiconductor Products, lnc., under MCl l2OP.

DESCRIPTION OF THE METHOD Stated generally, the present method comprises associating a piezoelectric transducer, such as is indicated at 17, with the string 13 (FIG. 3) of a hand-plucked musical instrument such as a guitar. The string 13 is then plucked by the fingers or by a handheld pick, and the resulting signal (FIG. 4) is fed through a very high-impedance circuit to a pulse separator and amplifier. The method then comprises separating each control pulse 37 (FIG. 4) from the remainder 38 of the wave, in order to derive the isolated control pulses illustrated in FIG. 5. Thereafter, each control pulse (or a counterpart thereof) is transmitted to gating means, and the music signal from the transducer 17 is also transmitted to such gating means (for example, the dual gate 90), whereby the music signal may not be transmitted unless (and to the extent that) the control pulse so permits. The resulting controlled signal from the transducer is amplified and delivered to a loudspeaker such as is represented at 94.

In the described manner, therefore, the guitarist or other musician has complete control over the tempo of the music, because such tempo is not solely determined by some preset electronic circuit but instead responds to the frequency of repetition of the control pulses 37, such frequency being under the direct control of the guitarist.

Stated more definitely, and with particular reference to the circuit illustrated in FIG. 1, the method of the invention comprises passing the indicated control pulses to the input of the bistable multivibrator 73. Assuming that switch 79 is closed, bistable 73 immediately transmits an output to lead 84. If switch 89 is closed and switch 88 is open, the signal from lead 84 is transmitted only through shaper 85 and to one control input of dual gate 90. Then, the signal which passes through lead 91 from transducer 17 to gate 90 is caused to have an envelope as indicated at 96. Such signal is amplified by amplifier 93 and converted by loudspeaker 94 to sound waves.

Triggering of bistable 73 also causes an output pulse to be delivered through lead 74 to monostable 75. Such monostable has a built-in time delay the duration of which may be predetermined by the musician. At the end of such time delay, and not before, output pulses are delivered both to monostable 76 and through switch (if in closed condition) to lead 84. Correspondingly,

monostables

76 and 77 each have builtin time delays which may be independently and individually preadjusted by the musician. Thus, after each such monostable 76 and 77 is triggered, and at the end of a time period predetermined by the guitarist, output signals are transmitted through the respective switches 81-82 (if closed) to lead 84.

The characteristics of the bistable multivibrator 73 are such that it will not transmit any additional output pulses until a clear signal is transmitted thereto through clear line 78 from the output of monostable 77. Therefore, once the bistable 73 has been initially triggered, it may not be triggered again until cleared by a pulse transmitted through clear line 78. It follows that all of the control pulses 37 which emanate from pulse separator 19 and monostable 70 will be of no effect until the bistable 73 is set by a pulse from the clear line. Then one, and only one, pulse 37 from the pulse separator and amplifier 19 will reinitiate the entire sequence of operation.

Let it be assumed, for example, that all of switches 79-82 are closed, that switch 88 is closed and switch 89 is open. The first control pulse delivered to bistable 73 causes operation of dual gate 90 to immediately transmit music having an envelope as shown at 97. Thereafter, and as soon as the monostable 75 delivers an output pulse, the dual gate 90 will again transmit a burst of music having the envelope 97. Third and fourth bursts of music then result in sequence, and with various time delays, when the

monostables

76 and 77 deliver their outputs to the shaper 87 and thence to the dual gate 90. Closing of switch 89 effects simultaneous transmission of pulses from line 84 through

bothshapers

85 and 87 to the dual gate, thereby creating superimposed envelope effects.

As but one of a very wide variety of modes of operation which may be effected, switch 79 may be closed, switches 80-82 may be opened and all of the

monostables

75, 76 and 77 may be set for exceedingly short time delays. Then, switch 88 is closed and switch 89 is opened so that the envelope 97 transmitted to dual gate 90 will be very short. With such a setting, each note struck by the guitarist will be operative to cause bistable 73 to transmit a pulse through shaper 87 to dual gate 90, but this pulse will be short and may, for example, simulate a banjo. Because of the exceedingly short time delays set in monostables 75-77, a clear pulse will be transmitted through line 78 to the bistable substantially immediately after transmission of an output pulse through switch 79 and shaper 87 to the gate 90.

Various other circuits, for example those simulating drum sounds, marimba sounds, etc., may be controlled by the control pulses in the manner described above relative to circuits 73 and 75-77. For example, let it be assumed that a drumsound generating circuit is substituted for switch 79, another such drum-sound circuit is substituted for switch 80, another is substituted for switch 81, and another is substituted for switch 82. Let it also be assumed that lead 84 is connected by circuit means, not shown, directly to amplifier 93 and thus to speaker 94. Accordingly, each time the circuits 73 and 75-77 produce outputs, drum sounds will be heard by a listener to the loudspeaker, and at time periods determined by die delays set in the monostables 75-77.

It is to be understood that, in a six-stringed instrument such as a guitar, six different ones of the circuits illustrated in FIG. 1 may be provided (one circuit for each string). However, all of the strings may feed into common amplifier 93 and loudspeaker 94. It is within the scope of the invention to cause different strings of the instrument to operate different instruments" (different sound-effect circuits).

It is to be noted that the music sound transmitted through lead 91 to dual gate-90 is normally continuous since the musician usually permits the string 13 to continue vibrating (dwell) after picking. I

it is within the scope of the invention to provide electromagnetic pickup means responsive to vibration of the various strings, in order to generate the wave of music voltage, and to use in association with such electromagnetic pickup means one or more piezoelectric transducers to generate control voltage pulses 37 as described heretofore in this specification.

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

lclaim:

l. A method of creating desired special musical effects with a stringed musical instrument of the type wherein the strings are plucked by the fingers or by a hand-held pick, which comprises:

employing a piezoelectric transducer to sense the vibrations of at least one string of said instrument,

whereby said transducer generates a control pulse of voltage in response to, and immediately upon, the release of said one string by a hand-held pick or by the fingers of the musician, and

whereby said transducer also generates a music wave of voltage after, and in response to, said release of said one string, and

employing said control pulse of voltage to create desired special musical effects.

2. The method as recited in claim 1, in which said method further comprises passing to amplifier and loudspeaker means at least part of the said music wave of voltage which is generated by said transducer after, and in response to, said release of said one string.

3. The invention as claimed in claim 1, in which said method further comprises separating said control pulse of voltage from the said music wave of voltage which is generated by said transducer after, and in response to, said release of said one string, and passing said control pulse of voltage to electronic circuit means adapted to create desired special musical effects.

4. The invention as claimed in claim 3, in which said method further comprises effecting said separation by passing said control pulse of voltage and said associated music wave of voltage into a very high-impedance load, whereby to cause said control pulse of voltage to be generally on one side of a horizontal axis, and whereby to cause said music wave of voltage to be offset primarily on the opposite side of said horizontal axis, and thereafter passing said control pulse of voltage and said music wave of voltage through pulse-separator circuitry adapted to produce an output comprising said control pulse of voltage and substantially free of said music wave of voltage.

5. The invention as claimed in claim 4, in which said method further comprises passing a voltage wave from said transducer to amplifier and loudspeaker means independently of said pulse-separator circuitry.

6. The invention as claimed in claim 1, in which said method further comprises passing a voltage wave from said transducer through gate means to amplifier and loudspeaker means, and employing sad control pulse of voltage to operate said gate means in a manner creating desired musical effects.

7. The invention as claimed in claim 1, in which said method further comprises employing said control pulse of voltage to create rhythm effects.

8. The invention as claimed in claim 1, in which said method further comprises passing a voltage wave from said transducer through gate means to amplifier and loudspeaker means, and employing said control pulse of voltage to effect operation of said gate means to block transmission of said voltage wave through said gate means a short time period after generation of said control pulse of voltage.

9. A method of creating rhythm effects with a stringed musical instrument of the type wherein the strings are plucked by a hand-held pick or by the fingers of the musician, which comprises:

providing a substantial number of multivibrator circuits in series relationship, at least the first of said multivibrator circuits being bistable,

deriving a clear signal from the last of said multivibrator circuits and supplying such signal to the clear input of said first and bistable multivibrator circuit,

deriving a control pulse of voltage from at least one string of said musical instrument in response to release of such string by the pick or finger of the musician,

feeding each such control pulse to said first multivibrator circuit,

whereby said first multivibrator circuit is caused to change state when one of said control pulses is received thereby, but only if such first multivibrator circuit is in cleared condition, and

generating sequential rhythm efiects in response to operation of said series-related multivibrator circuits,

whereby the musician can, by changing the frequency of repetition of releases of said string, control the repetition rate of the various sequences of generated rhythm effects.

10. The invention as claimed in claim 9, in which said method further comprises employing, as all of said multivibrators other than said first multivibrator circuit, monostable multivibrators the time delays of which may be predetennined by the musician.

11. The invention as claimed in claim 9, in which said method further comprises generating said rhythm effects by using the outputs of said multivibrators to control the operation of gate means, deriving from said instrument a musical signal corresponding to the vibration of a string of said instrument, and feeding said musical signal through said gate means to amplifier and loudspeaker means.

12. The invention as claimed in claim 11, in which said method further comprises employing shaper circuitry to control said gate means in response to actuation of said shaper circuitry by the outputs of said multivibrators, whereby the envelopes of the portions of said musical signal passed through said gate means correspond to the output of said shaper circuitry.

13. The invention as claimed in claim 9, in which said step of deriving said control pulse is effected by providing a piezoelectric transducer in association with said one string, and substantially separating said control pulse from the voltage wave generated by said transducer in response to plucking and consequent vibration of said string.

14. The invention as claimed in claim 9, in which said method further comprises deriving said control pulse of voltage immediately upon release of such string by the pick or finger of the musician.

l5. Circuitry for creating special musical effects in association with a guitar having piezoelectric transducer means to sense the vibrations of at least one string thereof, which comprises:

separator means adapted to be connected to said transducer means to receive the voltage wave therefrom and to separate from said voltage wave the control pulse of voltage which results from, and immediately upon, the release of at least one string of the guitar by the pick or finger of the guitarist,

means to generate special musical efi'ects, and

means to supply said control pulse to said special-effect generating means, whereby the operation of said special-efiect generating means is determined by the plucking of said one guitar string by the guitarist.

16. The invention as claimed in claim 14, in which amplifier and loudspeaker means are provided, and in which connector means are provided to connect said piezoelectric transducer means on the guitar to said amplifier and loudspeaker means.

17. The invention as claimed in claim 16, in which said connector means includes gate means, and in which means are provided to control said gate means in response to said control pulses.

18. The invention as claimed in claim 15, in which said circuitry is combined with a guitar wherein said piezoelectric transducer means is provided in engagement with at least said one string of the guitar.

19. Apparatus for generating special musical effects, which comprises:

a tensioned string adapted to be plucked by a hand-held pick or by the finger of a musician, a piezoelectric transducer provided in vibration-sensing relationship relative to said string whereby to generate a voltage wave corresponding to the vibrations of said string, said voltage wave including a control pulse portion responsive to and immediately following release of said string by a hand-held pick or by the finger of the musician,

said voltage wave also comprising a music portion following said control pulse portion and responsive to continued vibrations of said string,

means to substantially separate said control pulse portion from said music portion,

special-effect generating circuitry,

means to supply said separated control pulse portion to said special-effect generating circuitry, and

means to supply at least part of the voltage wave from said piezoelectric transducer to amplifier and loudspeaker means.

20. The invention as claimed in claim 19, in which said 'rneans to separate said control pulse portion from said music portion includes an impedance changer which presents a very high impedance to said piezoelectric transducer.

21. The invention as claimed in claim 20, in which said means to separate said control pulse from said music portion further comprises discriminator and clipper circuitry adapted to discriminate against said music portion and to transmit said control pulse portion.

22. The invention as claimed in claim 19, in which said special-effect generating circuitry includes gate means, means to control said gate means in response to said control pulse portion, means to supply to the input of said gate means the voltage wave from said piezoelectric transducer, and amplifier and loudspeaker means connected to the output of said gate means.

23. The invention as claimed in claim 19, in which said special-effect generating circuitry includes a substantial number of series-related multivibrator circuits, at least the first one of said multivibrator circuits being bistable, a clear line connecting an output of the last of said multivibrator circuits to the clear input of said bistable multivibrator circuit, in which means are provided to supply said control pulse portion to an input of said first and bistable multivibrator circuit, and in which said special-effect generating circuitry further includes means connected to the respective outputs of said multivibrator circuits to create special efiects whensaid various multivibrator circuits supply output pulses.

24. The invention as claimed in claim 23, in which at least some of said multivibrator circuits include time delay means variable by the musician in order to predetermine the time se uence of special effects.

5. The invention as claimed in claim 24, in which all of said multivibrator circuits excepting said first and bistable multivibrator circuit are monostable multivibrators.

26. The invention as claimed in claim 23, in which gate means are provided, in which means are provided to supply the voltage wave from said piezoelectric transducer to the input of said gate means, in which the output of said gate means is connected to amplifier and loudspeaker means, and in which shaper means are provided, the output of said shaper means being connected to a control terminal of said gate means, the input of said shaper means being connected to the outputs of said multivibrator circuits.

27. The invention as claimed in claim 26, in which switch means are provided to determine which multivibrator circuits are connected to said shaper means.

28. The invention as claimed in claim 26, in which first and second shaper means are provided, each of said first and second shaper means generating a wave of different shape, in which said gate means is a dual gate, in which the outputs of said shaper means are respectively connected to the two control terminals of said dual gate, and in which the inputs of said shaper means are connected to said various multivibrators.

29. The invention as claimed in claim 28, in which switch means are provided to detennine which of said shaper means is connected in the circuit.

30. Electrical musical instrument apparatus, which comprises:

a guitar having a string,

a piezoelectric transducer to support a portion of said string and thereby sense the vibrations thereof,

said transducer generating a control pulse of voltage in response to, and immediately upon, release of said string by a hand-held pick or by the fingers of the musician,

special-effect generating means, and

means to initiate operation of said special-effect generating means in response to said control pulse.

31. A method of creating special musical effects with a stringed musical instrument of the type wherein the strings are plucked by the fingers or by a hand-held pick, which comprises:

transducing the vibrations of at least one string of said instrument to thereby generate an electrical signal corresponding to the vibrations of such one string,

said vibrations and said corresponding signal occurring immediately upon release of the string and also after such release,

converting that part of said corresponding signal occuring immediately upon release of the string into a control pulse, and

employing said control pulse to initiate operation of an elec tronic means for generating a special musical sound effect.

8 i i l UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 468 Dated N v r 197] Inventor(s) Chauncey R. Evans It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 9, line 6 (line 1 of claim 16) cancel "14" and substitute 15 Signed and sealed this 26th day of December 1972.

(SEAL) EDWARD M.F1JETCHER,JR. ROBERT GOJJJJSCHALK Attesting Officer Commissioner of Patents

Claims

1. A method of creating desired special musical effects with a stringed musical instrument of tHe type wherein the strings are plucked by the fingers or by a hand-held pick, which comprises: employing a piezoelectric transducer to sense the vibrations of at least one string of said instrument, whereby said transducer generates a control pulse of voltage in response to, and immediately upon, the release of said one string by a hand-held pick or by the fingers of the musician, and whereby said transducer also generates a music wave of voltage after, and in response to, said release of said one string, and employing said control pulse of voltage to create desired special musical effects.

6. The invention as claimed in claim 1, in which said method further comprises passing a voltage wave from said transducer through gate means to amplifier and loudspeaker means, and employing said control pulse of voltage to operate said gate means in a manner creating desired musical effects.

9. A method of creating rhythm effects with a stringed musical instrument of the type wherein the strings are plucked by a hand-held pick or by the fingers of the musician, which comprises: providing a substantial number of multivibrator circuits in series relationship, at least the first of said multivibrator circuits being bistable, deriving a clear signal from the last of said multivibrator circuits and supplying such signal to the clear input of said first and bistable multivibrator circuit, deriving a control pulse of voltage from at least one string of said musical instrument in response to release of such string by the pick or finger of the musician, feeding each such control pulse to said first multivibrator circuit, whereby said first multivibrator circuit is caused to change state when one of said control pulses is received thereby, but only if such first multivibrator circuit is in cleared condition, and generating sequential rhythm effects in response to operation of said series-reLated multivibrator circuits, whereby the musician can, by changing the frequency of repetition of releases of said string, control the repetition rate of the various sequences of generated rhythm effects.

10. The invention as claimed in claim 9, in which said method further comprises employing, as all of said multivibrators other than said first multivibrator circuit, monostable multivibrators the time delays of which may be predetermined by the musician.

15. Circuitry for creating special musical effects in association with a guitar having piezoelectric transducer means to sense the vibrations of at least one string thereof, which comprises: separator means adapted to be connected to said transducer means to receive the voltage wave therefrom and to separate from said voltage wave the control pulse of voltage which results from, and immediately upon, the release of at least one string of the guitar by the pick or finger of the guitarist, means to generate special musical effects, and means to supply said control pulse to said special-effect generating means, whereby the operation of said special-effect generating means is determined by the plucking of said one guitar string by the guitarist.

19. Apparatus for generating special musical effects, which comprises: a tensioned string adapted to be plucked by a hand-held pick or by the finger of a musician, a piezoelectric transducer provided in vibration-sensing relationship relative to said string whereby to generate a voltage wave corresponding to the vibrations of said string, said voltage wave including a control pulse portion responsive to and immediately following release of said string by a hand-held pick or by the finger of the musician, said voltage wave also comprising a music portion following said control pulse portion and responsive to continued vibrations of said string, means to substantially separate said control pulse portion from said music portion, special-effect generating circuitry, means to supply sAid separated control pulse portion to said special-effect generating circuitry, and means to supply at least part of the voltage wave from said piezoelectric transducer to amplifier and loudspeaker means.

20. The invention as claimed in claim 19, in which said means to separate said control pulse portion from said music portion includes an impedance changer which presents a very high impedance to said piezoelectric transducer.

23. The invention as claimed in claim 19, in which said special-effect generating circuitry includes a substantial number of series-related multivibrator circuits, at least the first one of said multivibrator circuits being bistable, a clear line connecting an output of the last of said multivibrator circuits to the clear input of said bistable multivibrator circuit, in which means are provided to supply said control pulse portion to an input of said first and bistable multivibrator circuit, and in which said special-effect generating circuitry further includes means connected to the respective outputs of said multivibrator circuits to create special effects when said various multivibrator circuits supply output pulses.

24. The invention as claimed in claim 23, in which at least some of said multivibrator circuits include time delay means variable by the musician in order to predetermine the time sequence of special effects.

25. The invention as claimed in claim 24, in which all of said multivibrator circuits excepting said first and bistable multivibrator circuit are monostable multivibrators.

29. The invention as claimed in claim 28, in which switch means are provided to determine which of said shaper means is connected in the circuit.

30. Electrical musical instrument apparatus, which comprises: a guitar having a string, a piezoelectric transducer to support a portion of said string and thereby sense the vibrations thereof, said transducer generating a control pulse of voltage in response to, and immediately upon, release of said string by a hand-held pick or by the fingers of the musician, special-effect generating means, and means to initiate operation of said special-effect generating means in response to said control pulse.

31. A method of creating special musical effects with a Stringed musical instrument of the type wherein the strings are plucked by the fingers or by a hand-held pick, which comprises: transducing the vibrations of at least one string of said instrument to thereby generate an electrical signal corresponding to the vibrations of such one string, said vibrations and said corresponding signal occurring immediately upon release of the string and also after such release, converting that part of said corresponding signal occuring immediately upon release of the string into a control pulse, and employing said control pulse to initiate operation of an electronic means for generating a special musical sound effect.