US2250066A - Musical instrument - Google Patents

Description

July 22, 1941. J -r 2,250,066

MUSICAL INSTRUMENT Filed July 1'7, 1940 9 Sheets-S1158? 1 JAMES MIINA TT 1N VENTOR. :1- W

' ATTORNEY.

July 22, 1941. J. MANATT MUSICAL INSTRUMENT Filed July 17, 1940 9 Sheets-Sheet 3 Table of Control Frequencies iErrors peed Generated Freq.

S P. R

Frequency ofor Note Fig.

Fig. 6

JAMES MA NA TT INVENTOR. 5.

ATTORNEY.

July 22, 1941. J MANATT 2,250,066

MUS ICAL INSTRUMENT Filed July 17, 1940 9 Sheets-Sheet 4 JAMES MA NA T T INVENTOR.

lg ATTORNEY.

uly 22, 1941 J. MANATT 2,250,066

' MUSICAL INSTRUMENT Filed July 17, 1940 9 Sheets-Sheet 5 JAMES MANA T T- INVENTOR.

ATTORNE July 22, 1941. J. MANATT MUSICAL/INSTRUMENT Filed July 17, 1940 9 Sheets-Sheet 6 6 aqaaq q arm qdqqdaqJ JAMES MANA TT INVENTOR.

ATTORNEY.

July 22, 1941. J. MANATT 2,250,066

MUS ICAL INSTRUMENT Filed July 111940 9 Sheets-Sheet 7 JA MES MA NA r r INVENTOR.

ATTORNEY.

July 22, 1941.

J. .MANATT MUSICAL INSTRUMENT Filed July 17, 1940 9 Sheets-Sheet 8 JAMES MA NA TT INVENTOR.

ATTORNEY.

July 22, 1941.

J. MANATT 2,250,066 MUSICAL INSTRUMENT Filed July 17, 1940 9 Sheets-Sheet 9 115v.a.c.

JA ME 8 MA NA T T INVENTOR.

ATTORNEY.

Patented July 22, 1941 MUSICAL INSTRUMENT James Manatt, Chicago, Ill., assignor to Central Commercial Company, Chicago, 111., a corporation of Illinois Application July 1'1, 1940, Serial No. 345,928

15 Claims. (Cl. 841.17)

This invention relates to electrical musical instruments of the class in which tone signals may be selectively translated into acoustic energy of any desired waveform and same has particular reference to instruments employing a series of electron discharge devices coupled together in cascade so that the output signal from any device is ha'rmonically related to the output signal of the next preceding device of said series.

Certain frequency dividing systems with which I am acquainted employ relaxation oscillators comprising glow discharge or gas conten tubes electrically coupled together in cascade fashion to lock the tubes in step and obtain octave separation of their respective output signals, the first stage tube functioning in the system to control the input frequency. of the next preceding tube. Other systems comprise non-oscillatory dividing circuits in which "vacuum tubes, including a first stage tube are interconnected in cascade, likewise to obtain octave separation of their respective output signals, the first stage tube, however, receiving a controlling signalfrom an oscillating circuit which contains a master oscillator.

In frequency dividing systems which are the same or substantially similar to the aforementioned prior systems, it has been impossible to stabilize the output frequencies of the tubes or lamps employed and accuratelyto obtainoctave separation of said frequencies, due, largely, to variations in the circuit constants resulting from mechanical vibration, thermal and himidity effects, recognized instability of the tube elements, and various other causes.

Certain important objects of my invention are To provide means including a non-oscillatory controlling circuit for the first stage oscillator of a series of similar oscillators connected together in cascade, said means serving in a highly reliable manner always to transmit to said first stage, a controlling signal of invariable fundamental frequency.

To provide in combination with different sets of similarly cascaded oscillators, means other than frequency generators of the vacuum or gas content type for simultaneously and continuously producing fundamental frequencies and utilizing said frequencies to control the first stage 08- cillators of all sets of said similarly cascaded sets of oscillators.

To provide a highly reliable and exceedingly simple electro-mechanical controlling system for continuously generating musically related tone signals and simultaneously utilizing said signals to control all first stage oscillators of a plurality of similar sets of cascaded oscillators wherein the oscillators of each set respectively produce tone signals in octave relation.

To provide a musical instrument in which tone signals for a musical scale tuned in equal temperament are generated by similar oscillators.

To provide a musical instrument having means other than vacuum tubes or like electron discharge devices for generating controlling signals of invariable frequency and continuously utilizing said signals to control and stabilize the frequencies of "vacuum tube oscillators.

To provide an electrical musical instrument having simple and reliable mechanism for electro-magnetically generating controlling signals and utilizing said signals to control the first stage oscillators of different sets of similar oscillators.

To provide an electrical musical instrument having means for inductively generating controlling signals by the relative motion of coacting parts of alternators and periodically varying the frequency of said signals and similarly periodically varying the frequency of the output signals of all oscillators, whereby true vibrato effects can be selectively produced. 4 To provide an electrical musical instrument which remains in tune over long operating p riods of time and will not get out of tune as a result of shocks and jars transferred to its operating parts during transportation of the instrument and will not be subject to temperature and humidity conditions.

To provide a light weight and readily portable electrical musical instrument capable of accommodation in a small space and yet have the musical range of a large and less portable instrument.

To provide an electrical musical instrument consisting of a simplified organization of coacting elements for producing many pleasing musical results.

To provide an electrical musical instrument capable of closely simulating pipe organ tones.

To provide an electrical musical instrument in which a definite pitch relation is maintained between tone signals simultaneously and continuously generated, the retention of said pitch relation being due largely to the invariable rotational speed of a single motion transferring element which is common to corresponding driven parts of similar alternators.

To provide an electrical musical instrument in which the means for simultaneously and continuously generating controlling tone signals of invariable frequency embodies means in coaction therewith enabling the frequency of the generated signals to be varied periodically without changing the rotational speed of the aforementioned motion transferring element.

To provide an electrical musical instrument having oscillators coupled together in cascade to produce harmonically related output signals, the voltage levels of which are equal, thereby rendering unnecessary use of voltage regulators heretofore required for regulating the relative amounts of effective voltage musically necessary for correctly voicing the instrument.

To provide an exceedingly simple and compact mechanism which has none of the disadvantages of master oscillators, vacuum" tubes, "gas content" lamps, vibratile controlling devices, etc., the same continuously functioning to produce signals corresponding to the vibration frequencies of notes of the even tempered musical scale.

To provide a simple and inexpensive system of signal generators in which the rotational speeds of all generators are properly synchronized and cannot get out of step with each other, the result being that the pitch relation of the produced signals remains constant, notwithstanding occasional changes in line voltage.

Other objects and advantages of my invention will be more fully stated hereinafter and it is understood that I intend to claim as my invention all parts in their legitimate combinations'as well as various sub-combinations of the various legitimate combinations, and also to claim as my invention certain of the parts and mechanisms per se.

The invention will be readily understood from the following description and the accompanying drawings wherein certain preferred embodiments of the invention are shown and in which:

Figure 1 is an oscillator of a series of similar oscillators employed in my improved frequency dividing system.

Figure 2 is an illustration of the waveform of voltage produced by the oscillator shown in Figure 1.

Figure 3 is a view similar to Figure 1 showing a modified form of oscillator.

Figure 4 is an illustration of the waveform of voltage produced by the oscillator shown in Figure 3.

Figure 5 is a top plan view of my improved mechanism for generating controlling signals for all first stage oscillators employed in the instrument.

Figure 6 is a transverse section taken on the line AA of Figure 5.

Figure 7 is a diagrammatic illustration of my improved frequency dividing system.

Figure 8 is a diagrammatic illustration of a portion of an electrical network constituting my improved mixing system.

Figure 9 is a view similar to Figure 8 showing a continuation of the aforementioned mixing system.

Figure 10 is a diagrammatic illustration of the amplifier circuit at the output side of said mixing system.

Figure 11 shows a table of speeds and frequencies relevant to the mechanism shown in Figure 5.

Figure 12 is a block diagram of my improved musical instrument.

Figure 13 is a detail view of one of the frequency controlling wheels, and

Figure 14 is a schematic circuit diagram of means for controlling relative motion of coacting parts of the mechanism shown in Figure 5, whereby vibrato effects can be produced.

In Figure 1 an oscillator comprising a pentode tube of the remote cut off type is connected in an oscillatory circuit having a ground terminal II, a terminal l2 adapted to be connected with a non-resonant input signal path as will be more fully pointed out hereinafter, and output terminals I3 and H. The plate and the screen grid of said oscillator are supplied with direct current through resistors l and E in respective paths from a source of direct current shown at 2. Voltage from the source 3 is applied to the suppressor grid of the tube through a high resistance 8. This places a charge on said grid which is negative relative to the cathode and thereby limits the current drawn by the plate. Said negative charge on the suppressor grid produces a negative trans-conductance characteristic between the suppressor grid and the screen grid and the condition for oscillation is thereby obtained. In practice, satisfactory results are had with a source 2 providing 260 vol-ts, a source 3 providing 16 volts, a resistor 4 of 250,000 ohms, a resistor E of 100,000 ohms, a resistor l of 10 ohms, a resistor 8 of 500,000 ohms, a fixed condenser 9 of the value of .05 mfd. and a fixed condenser 5, the value of which is of course calculated according to the frequency of the output signal desired to be obtained. Since this fundamental oscillator circuit functions as a trigger circuit when oscillating, and the condenser charge and discharge is periochc, the output signal from the tube will be approximately as shown in Figure 2.

When a controlling signal in the form of a minute alternating current is applied to the resister I, the voltage developed across the resistor is applied to the control grid of the tube. This modulates the electron flow within the tube and the tube is thus predisposed to oscillate at some multiple of the controlling frequency. It is therefore obvious that if the tube is tuned to oscillate at a frequency which is near a multiple or submultiple of the controlling frequency, it will oscillate in step with said controlling frequency.

Should it be desired to produce a substantially sinusoidal output signal as shown in Figure 4, resistances 21 and 29 and capacitors 28 and 30 are incorporated in the circuit illustrated in Figure 3, said circuit being otherwise the same in every respect as the circuit shown in Figure 1.

In Figure 7, I show eight oscillator stages, each stage connected in a circuit which is the same in every essential particular as the circuit shown in Figure 1. As the relative values of the resistances and the capacitors illustrated in Figure 7 are as stated in the description of Figure 1, it need merely be said that said eight oscillator stages are electrically interconnected in cascade so as to lock said stages in step with one another and secure octave separation of their respective output signals.

It is assumed that the system of eight oscillators shown in Figure 7vis such that signals for all .A# notes in the instrument's gamut will be produced. As the highest frequency or first stage oscillator receives a controlling signal from the pick-up magnet 48 of the A# disc of the signal generating system shown in Figure 5, the frequency of the ,output signal from said oscillator will be 7380 cycles per second.

Bridged across the path 80, as shown. is a suppressor circuit consisting of a capacitor 81 and an inductor 88, whereby undesired frequencies in said path will be shunted out from the input of the first stage oscillator 8| at the lower right hand side of Figure 7 92 are plate resistors of uniform resistance value throughout the system; 84 the suppressor grid to screen grid coupling capacitors; 85 the screen grid resistors; 95 the suppressor grid resistors; 91 the control grid resistors; 88 the resistors in the resistance-capacitance filter sta e and 99 the capacitance elements of said filter stages, the value of each of which will of course vary according to the frequency to be filtered. I00 is a capacitor for blocking direct current from the mixing circuits shown in Figures 8 and 9.

IOI is a source of direct current which supplies the plate and screen currents for the respective oscillator stages and the negative biasing voltage for the suppressor grids.

I02 is a common ground connection and I 08 the capacitor for the first stage oscillator. Capacitor I04 serves the second stage, capacitor is connected to a shaft 58 by a flexible coupling comprising elements 58 and 58 and an intermediate element 50 of resilient material such as rubber. The shaft is journaled in longitudinally aligned bearings 48 on partitions 40, 4| and an latter comprising, in addition to said transverse yokes, a pair of parallel spaced apart side bars 44 situated inwardly of and spaced apart from the inner surfaces of the parallel side members 31 of said motor supporting frame, whereby said magnet frame is free to be tilted without contacting said surfaces.

Mounted on the shaft 58 and axially spaced apart from each other are similar circular discs 56 of magnetic material. Twelve such discs are employed in the present embodiment of my invention, such that there is one disc for each contlnuous controlling signalof invariable tone frequency necessary to be produced. Each disc has a bushing 51 firmly secured to the shaft to insure rotation of said disc with the shaft. These discs are respectively provided with 138, 146, 155, 164, 174, 184, 195, 207, 219, 232, 246 and 260 peripheral teeth as. disclosed in the third column from the left in the chart illustrated in Figure 11. Inasmuch as all said discs are fixedly mounted on a single driven shaft 58, it follows that with the shaft operating at a constant angular velocity of 30 R. P. S. the discs, in coaction with pickup devices to be described presently will respectively produce signals at the tone frequencies of notes of a scale tuned in equal temperament.

I05 the third stage and so on throughout the cascaded series of stages. These capacitors each connect indirectly to ground through the control grid resistor 9'1 of the following stage, with the exception of the capacitor IIO of the last and lowest frequency stage, the latter connecting directly to ground as at I02.

As the resistance 91 is low relative to any of the other resistances the frequency characteristics of the first stage oscillator are not appreciably disturbed by its insertion intothe tuning circuit. However, a small potential drop at the frequency of the first stage occurs across the resistor and this voltage is applied to the control grid of the next succeeding oscillator stage. If the next succeeding stage is tuned by capacitor I04 to oscillate at approximately 3690 cycles, then, the small E. M. I. applied to the control grid will lock it into step with said first stage oscillator and it will generate exactly 3690 cycles or A the frequency of said first stage oscillator. The capacitor I04 is connected to 9. corresponding control grid of the third stage and will lock it with respect to frequency. if it is tuned by capacitor I05 to approximately 1845 cycles per second.

1 The electrical impulses for supplying controlling signals at the vibration frequencies of the notes of the even tempered musical scale are produced by a mechanism which comprises a synchronous motor 85 operating at 1800 R. P. M. and adapted to be supplied with potential through a wire 36 from a 60 cycle, 115 volt source of alternating current. Said motor is mounted upon an end wall 88 of a suitable metallic supporting frame, the latter grounded at a. The shaft SI of the motor extends through said wall 88 and If the range of the gamut of my instrument is eight octaves, the frequency generated by the 138 tooth disc will be 4140 as compared with 4138.4 frequencies for-the note C of said scale. The disc having 146 teeth will generate a signal, the frequency of which is 4380 as compared with the vibration frequency 4384.5 corresponding to the note C# in the eight octave of said. scale,

and so on, to and inclusive of the disc having 260 teeth and which generates a signal, the frequency of which is 7800 as compared to 7812.3 frequencies corresponding to note B in said eight octave. This is important in that an essential feature of my invention resides in the employment of a simple mechanism by which all of the highest frequencies in each octave can be simultaneously and continuously generated and used to control the twelve first stage oscillators of my improved frequency dividing system which consists of twelve similar sets of oscillators in which the oscillators of each set generate signals in octave relation to each other, i. e.- there are twelve sets of oscillators, each set producing signals corresponding to all notes of the same octave letter. Obviously, if the range of the gamut is less than eight octaves, the total number of oscillators per individual cascaded series of oscillators will be reduced accordingly.

Carried by the left hand bar 44 of the magnet supporting frame is a set of six permanently magnetized threaded cores 50 of identical coils of spaced apart from the teeth of said disc. Said core freely passes through its bar 44 and has clamping nuts 52 by which the pointed tip of said core can be spaced any desired distance from the teeth of said disc. Each said coil has an output terminal 55.

By reason of the method of mounting the aforementioned magnet supporting frame, it follows that said frame can be tilted in an orbital path about the axis of the shaft 58, the motion of the tips of the cores 58 being concentric to the discs 56. Secured by nuts 45 to the sides 44 of the magnet supporting frame and preferably at the ends thereof nearest the motor 35 are studs 48. parallel sides of the motor supporting frame as shown in Figure 6. Coil springs 58 connect the studs 69 with the studs 45 and same serve yieldingly to maintain the magnet supporting frame in a state of perfect equilibrium so that alternating voltage generated at the pick-up magnets will be constant or of invariable frequency.

Mounted in the motor supporting frame are horizontally aligned electromagnets 54, each provided with a soft iron core 88. The broad flat tips of the cores 65 are very closely related to the end frame member 43 and are parallel. relative to the outer face of said member. The medial centers of said cores are substantially coincident with the upper edge of said member.

In Figure 14 is shown the control circuit for the pair of magnets 68 in Figure 5. This circuit comprises a transformer I82 having a primary winding I83 and secondary windings I84 and I85. The terminals of the secondary winding I84 are connected to the respective plates of a vacuum tube rectifier I81, the filament of which is connected to said primary winding I85. I92 is a magnet, the coil of which has one of its terminals tapped to the secondary winding I84 and connected with a vibratile reed I98. The other terminal of said coil joins the terminal I89 of coil I95 of one of said magnets 56. The opposite terminal of the coil I95 connects with the secondary winding I85. The terminal I89 isdisposed at one side of the reed I98. At the other side of the reed is a terminal I88 of the coil I98,

of the other magnet 56, the opposite terminal.

of said coil I98 connecting with said secondary winding I85. The armature I9I of the reed I98 is inductively related to the tip of the core of coil I92.

When the primary winding I83 of the transformer I82 is connected in circuit with a 115 volt alternating current source, the reed I99 is set in vibration at a rate which is determined by its mass and resiliency. When the reed contacts terminal I89, the circuit containing coil I95 is completed and the coil energized. Similarly, the coil I96 is energized when said reed contacts the terminal I88.

It manifestly follows that due to periodic alternate energization of the magnets 58 and corresponding periodic alternate deenergization thereof, the entire 'set of pick-up magnets 49 will Similar studs 89 are secured to the be rocked first clockwise and then counterclockwise against the normal equalizing tendency of the aforementioned springs 68. In consequence thereof, the frequency of all output controlling signals from the output terminals of said magnets 49 will vary slightly, as distinguished from the invariable or constant frequency of said signals produced when the magnets 49 are at rest or are in a perfect state of equilibrium- In order that the vibrato control circuit can be selectively closed when it is desired to convert the constant frequency output signals into signals, the frequencies of which vary periodically and more or less slightly, a switch I8Iia is connected in the wire I as shown. By reason of this method of periodically varying the frequency of said signals, true vibrato effects are obtained.

Except for certain omissions, the mixing system shown in Figures 8 and 9 is similar to the mixing system shown and described in my copending application Ser. No. 283,554, filed July 10, 1939. While I prefer to employ such system, I of course do not wish to be limited thereto, and accordingly reserve the right to substitute therefor any well known system that might possibly serve the purpose intended.

It will suffice merely to describe the system briefly and to point to certain novel features thereof in combination with my improved frequency dividing system herein disclosed and claimed.

I have stated that the frequency dividing system shown in Figure 7 consists of eight vacuum tube oscillators electrically interconnected or coupled together in a cascaded series so that their respective output signals are in octave relation, and that twelve substantially similar systems are employed, whereby all signals at the tone frequencres of a musical scale tuned in equal ternperament will be produced and made available for the compounding together of various tonal components. I have also pointed out that if the instruments gamut has a range of eight octaves, there will be eight oscillators per set of oscillators employed and that if the range embraces a lesser number of octaves, the number of oscillators per set will be correspondingly decreased. I have further stated that the system shown in Figure 7 furnishes signals corresponding to all the A# notes and that the highest frequency or first stage oscillator receives a continuous controlling signal from the pick-up magnet 49 of the A# disc 56 of the signal generating system shown in Figure 5.

In Figure 8, I show three playing keys I I9, corresponding to notes A#I, A#2 and A#9 of a single keyboard, it being understood that as many keyboards may be employed as shall be desired.

In Figure 9, three stops I29 of a system of stops are disclosed, such that any individual stop when close circuited in the network will render electrically effective a predetermined number of individual tone signals for the production of a waveform of voltage corresponding to a given timbre.

It now will be observed that of the entire set of eight oscillators shown in Figure 7, only seven thereof are connected in respective keying circuits shown in Figures 8 and 9. That is to say, the second oscillator stage is connected to the resistor H5 of the lowermost contact element III of the A#3 playing key. The third stage oscillator is similarly connected to the resistor II of the lowermost contact element of the A#2 playing key. In like manner, the fourth oscillator stage is connected to resistor H5 of the lowermost contact element III of playing key A#I. The eighth oscillator stage connects with the resistor H8 of the uppermost contact element of the A#I playing key, the signal from said stage corresponding to the sub-fundamental frequency of note A#I. Stage I connects to'the second resistor H8 from the top of the set used in association with the A#2 key, thus, the signal from said stage serves as the fundamental of the A#I note and as the sub-fundamental of the A#2 note. This is effected by a cross lead II5. Similarly, the various stages are employed in the network so that their signals serve as the fundamental frequencies of some notes and as partials the ground terminal I II through a resistor I25.

A branch lead I23 from said ground terminal has a contact element I22 for each contact element II1. When a key is elevated, the contact elements I I1 thereof engage associated elements I22 so that all elements III are at ground potential. When the key is depressed, the elements II1 thereof are moved by the sticker II8 into close circuit with respective contactors I2I. Each contactor I2I is electrically connected to an assigned one of the conductors I24, the order of the connections being such that each conductor will have transmitted thereto signals of a particular partial grouping, i. e. all signalsof the various fundamental frequencies will be impressedupon the second conductor I 24 at the left of the set shown in Figure 8. All second partial signals will be impressed upon the fourth conductor I24 from the left and so on throughout the system of conductors.

Each conductor I24 is connected to a contactor I26. These contactors are arranged in sets, such that there is one such set for each of the stops I29 shown in Figure 9.' Each stop comprises a set of contact elements I21 similar in number to the key contact elements II1 for each playing key, and each contact element I21 is normally open circuited relative to an associated contactor I26 and is adapted to be close circuited therewith when sticker I28 is moved in response to motion of the stop from a retired to a drawn position.

In each contact element I21 is a resistor I connected by a lead I3I to a preassigned tapped portion of a grading resistor I32, the latter having a terminal I32a connected to ground, as shown. The ground terminal III to which one terminal of the grading resistor is connected and the terminal I33 of said resistor are connected in circuit with the conventional signal amplifying system I44 and associated electroacoustic translating means I63 shown in Figure 10.

The resistors II6 are each 2 megohms. The resistors I30 are each megohm. Resistors I25 are each substantially .1 megohm. The resistor I32 is substantially .1 megohm. By calculating the relative values of the aforementioned resistors, true additive effects are had when depressing two or more keys which are simultaneously close circuited with the same signal generating source or when two or more stops are drawn and are 'close circuited with the same said signal generating source.

In the system disclosed in my copending application Ser. No. 283,554, use is made of electrostatic alternators for the production of various tone signals. By reason of the fact that such altemators were not of the same internal impedance, it was necessary to insert in each alternator and to earth a resistance by which an excess of generated voltage could be discharged to ground, as otherwise, the relative effective voltages from different altemators would be out of musical proportion when the signals were translated into acoustic energy. By discharging unwanted or excess voltage to ground, it was possible properly to voice the instrument. In the instant case, no such resistors are necessary as the voltto be such that the pitches and intensities for successive notes of the scale are correctly related to each other.

In Figure 12 is diagrammatically illustrated certain of the essential elements hereinbeforedescribed in detail and fully shown in the accompanying drawings. It will su'fiice briefly to state that the power pack I19 for supplying the vari ous stages of my frequency dividing systems has an input cable "I from an alternating current supply source and an'output I15 for supplying the respective stages. The signal generating system I61 has an input I66 from an alternating current supply source by which current is supplied the motor shown in detail in Figure 5. The output paths I61c from the respective pickup magnets of said signal generating system are connected with their appropriate filters in the filter system; I69 and the output paths I61d from said filters are formed into a cable I1!) and the latter accommodated in a rectilinear metallic housing I16. Said paths l61d connect with the control grids of theflrst stage oscillators of the respective cascaded systems of oscillators as will age levels of the generated signals will be found be understood. The output paths I61f from the oscillator stages connect with their associated playing keys as shown.

In order that any individual set of cascaded oscillator stages can be removed from and reinserted in the system whenever occasion therefor may arise, it will be noted that the twelve sets of stages shown in Figure 12 are arranged in parallel rows of six sets each and separated from each other by the aforementioned housing I16. Each individual set of oscillator stages is detachably connected with said housing by means of any well known plug and socket connectors I169 and "6h.

I have illustrated my invention in certain of its preferred embodiments, but wish it understood that nrodifications may be made and that no limitations upon my invention are intended other than may be imposed by the scope of the hereto appended claims.

What I claim as my invention is:

-1. In-an electrical musical instrument, twelve oscillating frequency dividing systems, each system including a plurality of oscillators electrically coupled together in cascade to secure octave separation of their respective output sig nals, a system comprising twelve generators respectively producing altemating voltages at the tone frequencies of notes of the even tempered musical scale, each generator including a circuit path for conduction of alternating voltage to the highest frequency oscillator of one of said frequency dividing systems, said generators each comprising a fixed part and a rotatable part, and a constant speed motor for simultaneously driving said rotary parts at the same angular ve-' locity.

2. An electrical musical instrument comprising a plurality of frequency dividing systems,

each said system having a plurality of oscillators electrically coupled together in cascade to secure octave separation of their respective output signals and including a high frequency first stage oscillator, a system including similar alternators respectively producing alternating voltages at predetermined tone frequencies, an output circuit lead connecting an alternator with the highest frequency oscillator of a respective frequency dividing system, said altemators each including a rotatable part, means for driving the rotary parts of the respective altemators at the same angular velocity and maintaining the output voltages of said altemators at constant frequency, and means selectively actuable periodically to vary the frequencies of said output voltages while maintaining said rotatable parts at said constant angular velocity.

3. In an electrical musical instrument, means for generating controlling signals for the first stage oscillators of respective sets of oscillators in which the oscillators of each set are electrically coupled together in cascade fashion to secure octave separation of their respective output signals, said means comprising alternating voltage generators of the same total number as said sets of oscillators and each generating alternating voltage of the frequency at which the first stage of an assigned set of oscillators is intended to oscillate and including a transmission path for conduction of said generated alternating voltage to said first stage oscillator, and means including a single driven element for synchronizing operation of all said generators.

4. In an electrical musical instrument, means for generating controlling signals for the first stage oscillators of respective sets of oscillators in which the oscillators of each set are electrically coupled together in cascade fashion to.

secure octave separation of their respective output signals, said means comprising rotary alternating voltage generators of the same total numher as said sets of oscillators and each generating voltage of the frequency at which the first stage of an assigned set of oscillators is intended to oscillate and including a transmission path for conduction of said generated alternating voltage to said first stage oscillator, and means for synchronizing operation of all of said generators, said synchronizing means comprising a synchronous motor having a single shaft driven thereby for simultaneously driving all of said generators at the same angular velocity.

5. In an electrical musical instrument, means for generating alternating voltages at different tone frequencies and utilizing said voltages continuously to stabilize the first stage oscillators of different sets of oscillators inwhich the oscillators of each set are electrically coupled together in cascade to lock said oscillators in step with each other and secure octave separation of their respective output signals, said means comprising a separate generator for the first stage oscillator of each set of oscillators, each generator including a rotary part of magnetic material and a permanent pick-up magnet, said magnet including an output circuit path to said first stage oscillator, and means for simultaneously driving said rotary parts at the same angular velocity.

6. In an electrical musical instrument, twelve sets of oscillators, the oscillators of each set of oscillators electrically coupled together in cascade to secure octave separation of their respective output frequencies, an output circuit path from each oscillator, twelve alternating voltage generators, each generator continuously producing alternating voltage of the frequency of the output signal of the highest frequency oscillator stage of a particular set of said oscillators, each generator including a rotary part and a part inductively related thereto, and means for simultaneously driving said rotary parts at the same angular velocity.

7. In an electrical musical instrument, a plurality of sets of oscillators, the oscillators of each set electrically coupled together in cascade and including a first stage oscillator having an input circuit path, each said oscillator having an output circuit path for conduction of a tone signal to an acoustic translating means, and means for establishing and stabilizing the output frequency of the first stage oscillators and comprising a rotary alternator for and connected with the input circuit path of each first stage oscillator for continuous transmissionto said oscillator of a controlling signal and means for constantly operating said alternators, each at the same angular velocity.

8. A device for electrically producing signals adapted respectively to be impressed upon the control grids of the first stages of different sets of vacuum tube oscillators in which the oscillators of each set are connected in cascade to lock same in step with one another and secure octave separation of their output frequencies, a synchronous motor, a rotary shaft directly and continuously operated by and at the synchronous speed of said motor and having a predetermined number of axially related signal generating members, a pick-up device for and inductively related to each signal generating member and provided with a signal transmitting path adapted to be connected to the control grid of the first stage oscillator of a set of such oscillators, means supporting all of said pick-up devices for yieldable to and fro motion concentrically of the respective signal generating members, and means for selectively operating said supporting means to effect said to and fro motion of said pick-up devices.

9. A device for electrically producing signals adapted respectively to be impressed upon the control grids of the first stages of different sets of oscillation generators in which the generators of each set are connected in cascade to lock said generators in step with one another and secure octave separation of their output frequencies. a synchronous motor, a rotary shaft directly and continuously operated by and at the synchronous speed of said motor and having a predetermined number of axially related signal generating members, a pick-up device for and inductively related to each signal generating member and provided with a signal transmitting path adapted to be connected to the control grid of the first stage oscillation generator of a set of such generators, means supporting all of said pick-up devices for simultaneous to and fro motion concentrically of the respective signal generating devices, means serving normally yieldingly to resist to and fro motion of said pick-up devices, and selectively actuable means for causing said to and fro motion against the normal tendency of said motion resisting means.

10. In an electrical musical instrument employing a plurality of electrical oscillation generators coupled together in cascade to lock said generators in step with one another and secure octave separation of their respective output frequencies and including a first stage adapted to be supplied with a controlling signal, a pulsation generator for supplying said controlling signal and comprising a normally immovable part and a rotary part, the latter inductively related to and serving to produce in the former a controlling signal of predetermined tone frequency, a rotary shaft upon which said rotary part is fixed, a synchronous motor coupled to and driving the shaft at a constant angular velocity, movably mounted means yieldingly supporting said normally immovable part for clockwise and counterclockwise motion relative to the axis of rotation of said shaft, a pair of magnets associated with said supporting means, and selectively actuable means for alternately energizing and deenergizing said magnets to thereby impart the aforementioned clockwise and counter-clockwise motion to said normally immovable part.

11. An electrical pulsation alternator including a pick-up device adapted for oscillatory motion, and means for causing oscillatory motion of said device and comprising a circuit having connected therein a pair of magnets and a single magnet, a vibratile member having an armature associated with and operated by said single magnet, a pair of make and break contacts connected in said circuit and with the magnets of said pair of magnets to efiect alternate energization and deenergization of the latter, and means for periodically exciting said single magnet to operate said armature as aforementioned and periodically vibrate said vibratile member.

12. In mechanism of the class described, a plurality of frequency dividing systems, each of said systems comprising a set of vacuum tube oscillators electrically coupled together to secure octave separation of their respective output frequencies and including a first stage, a system of non-resonant oscillatory circuits such that one each of said circuits is connected with and supplies a respective first stage with a controlling frequency,

and means common to'all of said circuits for causing oscillation thereof each at a predetermined frequency difierent from that of any of the others. 7

13. In mechanism of the class described, a plurality of frequency dividing systems, each of said systems comprising a set of vacuum tube oscillators electrically coupled together to secure octave separation of their respective output frequencies and including a first stage, a system of non-resonant oscillatory circuits such that one each of said circuits is connected with and supplies a respective first stage with a controlling frequency, and means common to all of said circuits for causing oscillation thereof at predetermined tone frequencies and comprising a rotary pulsation alternator for and connected with each individual one of said circuits, and a synchronous motor for simultaneously driving said alternators at a common angular velocity.

14. An electrical musical instrument comprising twelve vacuum tube oscillation generators; twelve rotary pulsation generators, each rotary pulsation generator producing a controlling signal of the tone frequency of one of the notes of the even tempered musical scale; a circuit path connecting each individual rotary alternator with a respective vacuum tube oscillation generator for delivery thereto of a controlling signal; and means common to all of said rotary pulsation alternators for driving same at the same angular velocity.

15. In an electrical musical instrument, a frequency generating system embodying twelve sets of oscillation generators, each set of said oscillation generators comprising similar thermionic valves electrically coupled together in cascade fashion to secure octave separation of their output oscillations and including a first stage upon the control electrode of which controlling impulses are adapted to be'impressed, and a frequency controlling mechanism comprising a set of pulsation generators, there being one such impulse generator for each individual first stage oscillation generator, each individual impulse generator comprising a movable part and a part inductively related thereto and provided with an output terminal connected with the control electrode of the first stage of a respective one of the aforementioned sets of oscillation generators; and means common to the movabl parts of the individual impulse generators for driving them at the same speed.

JAMES MANA'I'I.

Images