US3283057A - Keyboard oscillator circuit - Google Patents

Keyboard oscillator circuit Download PDF

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Publication number
US3283057A
US3283057A US378296A US37829664A US3283057A US 3283057 A US3283057 A US 3283057A US 378296 A US378296 A US 378296A US 37829664 A US37829664 A US 37829664A US 3283057 A US3283057 A US 3283057A
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United States
Prior art keywords
capacitor
keyboard
transistor
voltage
resistors
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US378296A
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English (en)
Inventor
Jr Richard H Campbell
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Seeburg Corp
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Seeburg Corp
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Publication date
Application filed by Seeburg Corp filed Critical Seeburg Corp
Priority to US378296A priority Critical patent/US3283057A/en
Priority to DES97634A priority patent/DE1290415B/de
Priority to GB26251/65A priority patent/GB1065252A/en
Application granted granted Critical
Publication of US3283057A publication Critical patent/US3283057A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10H—ELECTROPHONIC MUSICAL INSTRUMENTS; INSTRUMENTS IN WHICH THE TONES ARE GENERATED BY ELECTROMECHANICAL MEANS OR ELECTRONIC GENERATORS, OR IN WHICH THE TONES ARE SYNTHESISED FROM A DATA STORE
    • G10H5/00—Instruments in which the tones are generated by means of electronic generators
    • G10H5/02—Instruments in which the tones are generated by means of electronic generators using generation of basic tones
    • G10H5/04—Instruments in which the tones are generated by means of electronic generators using generation of basic tones with semiconductor devices as active elements

Definitions

  • This invention relates generally to electronic musical instruments and more particularly to an oscillator circuit for such instruments which can be frequency controlled in a manner to derive the tone frequencies individual to the keys of a keyboard for the full tone frequency range of the keyboard.
  • a feature of the invention is the provision of all solid state components in a novel tone generator circuit that permits a wide range of tones to be generated with accuracy and repeatability in a circuit which is inherently stable to achieve faithful tone reproduction which is maintained for long periods of time and is relatively simple to recalibrate, i.e. retun'e, by means of simple adjustments than can be made in the home.
  • an output keying circuit for applying the oscillator derived tone frequency to suitable voicing circuits and arrangments for selectively sustaining individual tone signals after the key which produced such signals has been released by the player.
  • a keyboard voltage divider 2a is connected between the terminals 11 and 12 via a path which runs from terminal 11 through an adjustable resistor 13 and a series of fixed resistors 14, 15, 16, 17, 18, 19, 21 and a line connecting resistor 21 to terminal 12. As indicated, between resistors 17 and 18 any desired number of additional resistors may be present in the voltage divider.
  • a shunt resistor 22 is connected from the terminal 11 to the junction of resistors 19 and 21.
  • a set of tuning contacts 23 is connected with one transfer contact 24 for each resistor 15 through 19 of the voltage divider 20.
  • the transfer contact 24 is normally engaging contact 25, which is connected to the next transfer contact of the set of switches 23.
  • the transfer contact 24 makes contact with contact 26, thereby applying to the transfer contact 24 the voltage existing at the junction of resistors 15 and 16.
  • the transfer contacts 24 normally engaging the contacts 25 are connected to the next lower voltage transfer contact so that upon actuation of any key a voltage is applied serially through the remaining lower voltage steps of the set of switches 23 to apply the selected junction voltage from the voltage divider 20 to a storage capacitor 27.
  • the capacitor 27 will be charged to the difference in potential between the positive fifteen volt supply from For this purpose any ice terminal 11 and the voltage exisiting at the junction of resistors 15 and 16. It will be noted with the arrangement of the set of switches 23 that if two keys are depresssed simultanteously resulting in the transfer switching of two contacts 24 of the set, only the lower voltage contact is effective to transfer a potential to the capacitor 27.
  • the voltage across capacitor 27 determines the base potential of a transistor 31 which forms the input of a solid state integrator feedback network 32, the output of which on line 33 is a low impedance voltage source, the magnitude of which represents the level of charge of capacitor 37.
  • This voltage is applied through a resistor 34 and an adjustable resistor 35 to the emitter of a transistor 36 which operates to convert the voltage input to a constant current output representative of the voltage level on line 33.
  • the collector of transistor 36 is connected to charge a capacitor 37 relative to ground.
  • the capacitor 37 is connected across the junction of a unijunction transistor 38.
  • the transistor 38 has one base connected to ground at 39, an emitter lead 41 connected to the junction of capacitor 37 and the collector of transistor 36 and the other base electrode is connected through a 680 ohm resistor 42 to the positive fifteen volt supply from terminal 11.
  • the charge across capacitor 27 is translated by the solid state memory circuit 32 into a voltage on line 33 which accurately represents and maintains the level of the voltage divider 20 which has been selected by one of the switches 24.
  • the voltage on line 33 is converted into a constant current analogue by the transistor 36 and charges the capacitor 37 until the voltage across the capacitor 37 reaches the breakdown voltage level for the emitter 41 of the unijunction transistor 38.
  • the capacitor 37 Upon breakdown of the junction of the transistor 38 the capacitor 37 is discharged, the junction of transistor 38 becomes nonconductive and the relaxation oscillation consisting of alternately charging and discharging capacitor 37 occurs at a frequency determined by the current magnitude delivered by the transistor 36.
  • This wave across capacitor 37 is utilized to derive tone frequency signals which are integrally related to the frequency of the relaxation oscillation across.
  • the wave across capacitor 37 is coupled to two cascaded flip-flop stages 43 and 44 which ope-rate as binary counters to produce an output on line 45 which is a square wave of one-half the relaxation oscillation input frequency and from line 46 a square wave which is one-half of the frequency of the square wave on line 45.
  • the square waves on lines 45 and 46 are coupled to output terminals 47 and 48 respectively whenever diodes 51 and 52 are conductive.
  • the output on terminal 47 will correspond to the eight foot output tone range of 64 to 256 cycles per second and the tone range on terminal 48 will correspond to the sixteen foot output of 32 to 128 cycles per second.
  • a set of keying contacts 53 is provided for enabling the diodes 51 and 52 to pass the tone signals to the output terminals 47 and 48.
  • this keying circuit has an individual contact 54 ganged with the corresponding transfer contact 24 of the switch 23.
  • a single contact could be employed actuated by any individual transfer switch 24 of the set of contacts 23. Actuation of any key in the keyboard to operate the one contact 24 will also operate the keying contact 54 associated therewith to apply positive potential from terminal 11 to a line 55 which is connected to a diode 56 poled to be conductive when the positive voltage is applied by the switch 54.
  • capacitor 57 When diode 56 is conductive a large storage capacitor 57 is charged to a fixed voltage corresponding to the supply voltage from terminal 11.
  • the capacitor 57 is connected to the base of a transistor 58 and the voltage across the capacitor 57 determines the base voltage of the transistor 58.
  • the transistor 58 With capacitor 57 charged to a positive potential the transistor 58 becomes conductive applying positive potential from terminal 11 to the midpoint of two resistors 61 and 62 which are bridge connected with two additional resistors 63 and 64 to control conduction of the diodes 51 and 52.
  • switches 71 and 72 By means of switches 71 and 72, two resistors 66 and 67 may be connected as alternate discharge .paths for the capacitor 57 and by selecting the values of the resistors 66 and 67 different discharge time constants can be obtained. Accordingly, with switches 71 and 72 closed, the charge on capacitor 57 leaks off in a relatively rapid manner and the transistor 58 is cut off shortly after the key which actuated switch 54 is released, thereby controlling the time in which the diodes 51 and 52 become nonconductive to stop the transmission of tone signals to the output terminals 47 and 48. With either or both of switches 71 and 72 open, a longer sustained tone is achieved.
  • the disclosed circuit provides an all solid state relaxation oscillator controlled by a frequency control signal derived from a memory circuit which maintains the frequency constant at its established level for each key that is played.
  • the output keying circuit controls the application of the ultimate tone frequency signals to the output terminals and permits sustained or decaying signals to be obtained.
  • the unijunction transistor 38 may be a commercial type 2N2646 and provides with capacitor 37 a relaxation oscillator for maintaining the desired frequency from which the tone frequencies are derived. By adjusting the resistance 13 the voltage increments across the successive resistors 15-22 of the voltage divider 20 can be established thereby determining the tuning spread or frequency increment represented by the voltage across each resistor of the voltage divider 20.
  • the appropriate frequency increment can be obtained to make the successive keys of the keyboard which operate the transfer switches 24 related in accordance with the musical tone scale.
  • the tuning range for the oscillator 38 can be established thereby permitting the frequency range for the total span of voltage increment to correspond to the total frequency range for the keyboard instrument.
  • the complete tuning of the instrument can be accomplished by means of the two adjustments for resistors 13 and 35 in a relatively simple manner and by the nature of the regulated voltage supplies and the inherent stability of the solid state circuits the tuning can be maintained accurately for long periods of time.
  • a keyboard operated tone generator comprising a unijunction transistor, a capacitor connected across the junction of said transistor, a controlled variable charging circuit for said capacitor said charging circuit including a constant current transistor connected to charge said capacitor and a transistor feedback circuit connected to control said constant current transistor to supply a predetermined range of current values, a keyboard, an adjustable resistor and a plurality of fixed resistors proportioned according to the notes of said keyboard connected in series across a regulated voltage source, a memory capacitor, switch means operated by the keys of said keyboard to charge said memory capacitor to the voltage between adjacent ones of said resistors corresponding to the actuated key of said keyboard, a connection from said memory capacitor to the input of said feedback circuit for controlling said charging circuit to make the relaxation period for charging said capacitor connected across said junction to the voltage breakdown level of said junction inversely related to the tone frequency for said actuated key, means for coupling a .pulse wave from said transistor corresponding to the frequency of breakdown of said junction, and means responsive to said pulse wave for deriving a tone frequency wave integrally related

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Electrophonic Musical Instruments (AREA)
  • Inductance-Capacitance Distribution Constants And Capacitance-Resistance Oscillators (AREA)
US378296A 1964-06-26 1964-06-26 Keyboard oscillator circuit Expired - Lifetime US3283057A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US378296A US3283057A (en) 1964-06-26 1964-06-26 Keyboard oscillator circuit
DES97634A DE1290415B (de) 1964-06-26 1965-06-15 Mittels einer Tastatur betaetigter Tongenerator, insbesondere fuer ein elektronisches Musikinstrument
GB26251/65A GB1065252A (en) 1964-06-26 1965-06-22 Keyboard oscillator circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US378296A US3283057A (en) 1964-06-26 1964-06-26 Keyboard oscillator circuit

Publications (1)

Publication Number Publication Date
US3283057A true US3283057A (en) 1966-11-01

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Family Applications (1)

Application Number Title Priority Date Filing Date
US378296A Expired - Lifetime US3283057A (en) 1964-06-26 1964-06-26 Keyboard oscillator circuit

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Country Link
US (1) US3283057A (de)
DE (1) DE1290415B (de)
GB (1) GB1065252A (de)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3490327A (en) * 1966-08-26 1970-01-20 Excelsior Accordians Inc Multivibrator frequency divider chain for musical instrument employing a master oscillator which is step frequency adjustable and a twin-t vibrato oscillator
US3497605A (en) * 1967-12-04 1970-02-24 Jasper Electronics Mfg Corp Circuit for obtaining repeater and percussion effects in an electrical musical instrument utilizing a field effect transistor
US3511917A (en) * 1967-04-10 1970-05-12 Seeburg Corp Voltage selection arrangement wherein same contacts switch selectable d.c. pitch potential and constant a.c. for control function
US3655904A (en) * 1970-12-14 1972-04-11 Herbert Cohen Electric variable tone percussion instrument
US3688009A (en) * 1970-11-13 1972-08-29 Seeburg Corp Musical device for automatically producing tone patterns
US3715442A (en) * 1970-12-15 1973-02-06 A Freeman Chord tone generator control system
US3766305A (en) * 1972-07-17 1973-10-16 Hammond Corp D.c. keyed high low select preference system for polyphonic electrical musical instruments
US3789718A (en) * 1971-12-30 1974-02-05 Baldwin Co D H Voltage controlled chord organ
US3813474A (en) * 1972-08-25 1974-05-28 Wurlitzer Co Electronic musical instrument circuit
US3902392A (en) * 1973-05-25 1975-09-02 Nippon Musical Instruments Mfg Electronic musical instrument of voltage-controlled tone production type
US3918342A (en) * 1973-09-14 1975-11-11 Keio Giken Kogyo Kabushikikais Monophonic electronic musical instrument of equal tempered scale
US3991645A (en) * 1975-06-14 1976-11-16 Norlin Music, Inc. Electronic musical instrument with exponential keyboard and voltage controlled oscillator

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2403664A (en) * 1942-10-24 1946-07-09 Central Commercial Co Solo electrical musical instrument
US2483823A (en) * 1947-04-07 1949-10-04 Thomas J George Electronic keying means
US2486208A (en) * 1947-08-23 1949-10-25 Bell Telephone Labor Inc Electronic musical instrument
US2540727A (en) * 1945-05-05 1951-02-06 Hammond Instr Co Electrical musical instrument
US2792738A (en) * 1954-04-28 1957-05-21 William A Donahue Fretted electronic musical instrument
US2987577A (en) * 1955-08-23 1961-06-06 Automatic Elect Lab Time division multiplex system
US3114114A (en) * 1960-11-09 1963-12-10 Robert R Atherton Voltage controlled ramp and pulse generator
US3180918A (en) * 1961-01-26 1965-04-27 Conn Ltd C G Tone generator system
US3196201A (en) * 1961-04-26 1965-07-20 Conn Ltd C G Transistor keyer
US3214708A (en) * 1962-03-28 1965-10-26 Gen Electric Frequency-type telemeter transmitter

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2403664A (en) * 1942-10-24 1946-07-09 Central Commercial Co Solo electrical musical instrument
US2540727A (en) * 1945-05-05 1951-02-06 Hammond Instr Co Electrical musical instrument
US2483823A (en) * 1947-04-07 1949-10-04 Thomas J George Electronic keying means
US2486208A (en) * 1947-08-23 1949-10-25 Bell Telephone Labor Inc Electronic musical instrument
US2792738A (en) * 1954-04-28 1957-05-21 William A Donahue Fretted electronic musical instrument
US2987577A (en) * 1955-08-23 1961-06-06 Automatic Elect Lab Time division multiplex system
US3114114A (en) * 1960-11-09 1963-12-10 Robert R Atherton Voltage controlled ramp and pulse generator
US3180918A (en) * 1961-01-26 1965-04-27 Conn Ltd C G Tone generator system
US3196201A (en) * 1961-04-26 1965-07-20 Conn Ltd C G Transistor keyer
US3214708A (en) * 1962-03-28 1965-10-26 Gen Electric Frequency-type telemeter transmitter

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3490327A (en) * 1966-08-26 1970-01-20 Excelsior Accordians Inc Multivibrator frequency divider chain for musical instrument employing a master oscillator which is step frequency adjustable and a twin-t vibrato oscillator
US3511917A (en) * 1967-04-10 1970-05-12 Seeburg Corp Voltage selection arrangement wherein same contacts switch selectable d.c. pitch potential and constant a.c. for control function
US3497605A (en) * 1967-12-04 1970-02-24 Jasper Electronics Mfg Corp Circuit for obtaining repeater and percussion effects in an electrical musical instrument utilizing a field effect transistor
US3688009A (en) * 1970-11-13 1972-08-29 Seeburg Corp Musical device for automatically producing tone patterns
US3655904A (en) * 1970-12-14 1972-04-11 Herbert Cohen Electric variable tone percussion instrument
US3715442A (en) * 1970-12-15 1973-02-06 A Freeman Chord tone generator control system
US3789718A (en) * 1971-12-30 1974-02-05 Baldwin Co D H Voltage controlled chord organ
US3766305A (en) * 1972-07-17 1973-10-16 Hammond Corp D.c. keyed high low select preference system for polyphonic electrical musical instruments
US3813474A (en) * 1972-08-25 1974-05-28 Wurlitzer Co Electronic musical instrument circuit
US3902392A (en) * 1973-05-25 1975-09-02 Nippon Musical Instruments Mfg Electronic musical instrument of voltage-controlled tone production type
US3918342A (en) * 1973-09-14 1975-11-11 Keio Giken Kogyo Kabushikikais Monophonic electronic musical instrument of equal tempered scale
US3991645A (en) * 1975-06-14 1976-11-16 Norlin Music, Inc. Electronic musical instrument with exponential keyboard and voltage controlled oscillator

Also Published As

Publication number Publication date
GB1065252A (en) 1967-04-12
DE1290415B (de) 1969-03-06

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