|Publication number||US3085460 A|
|Publication date||Apr 16, 1963|
|Filing date||Aug 14, 1961|
|Priority date||Aug 14, 1961|
|Publication number||US 3085460 A, US 3085460A, US-A-3085460, US3085460 A, US3085460A|
|Inventors||Thomas C Edwards|
|Original Assignee||Thomas C Edwards|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (2), Referenced by (25), Classifications (12)|
|External Links: USPTO, USPTO Assignment, Espacenet|
April 16, 1963 T. c. EDWARDS 3,085,460
PORTABLE ELECTRONIC MUSICAL INSTRUMENTS Filed Aug. 14. 1961 ,2- FIG. I
Amenna in Shielded Pas/flan 50 Receiver, 49 INVENTOR. i AmpII'fI'eI; Thomas 0. Edwards 1 51 5 l l Speaker United States? 3,085,460 Patented Apr. 16, 1963 3,685,468 PORTABLE ELECTRGNIC MUSICAL INSTRUMENTS Thomas C. Edwards, Los Alamos, N. Mex. (351-C, Rte. 1, Espanola, N. Mex.) Filed Aug. 14, 1961, Ser. No. 131,134 2 Claims. (Cl. 84-1) This invention relates to a portable electronic musical instrument, i.e., one which is to be carried by a performer, and it pertains more particularly to an improved system for eliminating the external connector-cable which has heretofore been used with such electronic musical instruments.
Although radio link sound pickups have long been known (US 2,710,345, Walkie-Talkies, etc.) electronic guitars, which are also old and well know, have heretofore required a cable between said guitar and a speaker; an object of this invention is to eliminate the necessity of such external cable. A further object is to provide an improved transmitter-power assembly for portable electronic musical instruments with the antenna thereof so positioned that it does not come close enough to any part of the performers body to distort or interfere with transmitted signals and does not protrude in a direction which might bring it into contact or too close proximity to other performers or objects. A further object of the invention is to provide new tone and sound effects which cannot be duplicated with cable-to-speaker systems without the use of expensive and complicated circuitry. Other objects will become apparent as the detailed desription of the invention proceeds.
Briefly, I employ a small transmitter powered by a small battery in an assembly small enough to fit into the musical instrument which provides the source of mechanical sound vibrations. For an electronic guitar this assembly may be about 1.5 x 2" x 3", or even smaller. A conventional transducer system may be employed for converting the sound vibrations to electrical signals, but these signals are conducted within the instrument itself to the transmitter-power assembly instead of being connected by an external cable to a speaker. The transmitter circuit is preferably one which employs a tunnel-diode, i.e., is a tunnel diode oscillator circuit, though other transmitting circuits may be used. A tunnel diode is a germanium semiconductor device described and characterized in detail in Tunnel Diode Manual, copyright 1961 by General Electric Co., the ratings and characteristics of such tunnel diodes being set forth on pages 11 to 17, 87 and 95 of said manual; tunnel diode oscillator circuits are shown on pages "33 to 42 of said manual and are exemplified by the circuit on page 41 thereof using the 1N2939 tunnel diode.
The transmitter and particularly the antenna thereof should be so mounted as to provide shielding from too close proximity to parts of a performers body or to external objects; nothing having a capacitance effect should come closer than about an inch and preferably not closer than two inches to the antenna. By mounting the antenna on or within a guitar or other stringed instrument about 2 to 3 inches above the fretted neck and substantially parallel thereto, it is protected by the flexed left arm of the performer from external physical contacts or electrical disturbance or drift. To avoid dead spots, a plurality of antennas may be used, i.e., either the instrument or the receiver-speaker may have at least two antennas spaced about one to three feet or more apart; it is usually undesirable to have a second antenna on the instrument and hence it is preferred that the receiver be provided with spaced antennas.
The transmitter and receiver should of course be tuned to the same frequency and it is desirable that a variable frequency transmitting circuit be employed, the variation being obtainable by using a variable condenser or by plugging in crystals of different frequency or by any other known means. When a number of electronic musical instruments are playing together as in a band or orchestra, each should be tuned to its respective receiver. A microphone may be plugged into a jack on the instrument for transmitting the performers voice with the guitar music.
The invention will be more clearly understood from the following detailed description of a preferred example thereof read in conjunction with the accompanying drawings which form a part of this disclosure and in which:
FIGURE 1 is a view of an electronic guitar showing the position of the transmitter and antenna with respect to the body of the performer playing the instrument.
FIGURE 2 is a schematic diagram of the transmitter circuit showing its relationship with the other parts of the combination.
While an electronic guitar will be described in detail as my preferred example, it should be understood that my invention is applicable to any other electronic musical instrument that is carried by a performer, particularly to those characterized by vibrating strings or reeds.
Referring to FIGURE 1, performer 10 is playing an electronic guitar 11 which is supported by shoulder strap 12 with end openings engaging supporting buttons 13 and 14. The performers left hand 15 normally comes under and around the fretted neck so that the fingers of the left hand may press strings 16 against frets 17, the lower part of the instrument being curved inwardly adjacent the fretted neck to permit the fingers of the left hand to reach the lowermost frets. The performers right hand 18 is normally above strings 16 just beyond bridge 19, the strings being strummed, plucked or otherwise vibrated by the fingers and/or thumb of said right hand. The strings are anchored to holding plate 20 in any known manner, and they are tuned at the upper end of the fretted neck by any means known to the art.
Since the guitar is an electronic instrument, it is provided with the usual transducer system, which includes one or more transducers. I preferably employ one transducer 21 spaced about six inches from the bridge 19 and another transducer 22 spaced quite close (within an inch or so) to said bridge. Transducer systems are well known and hence require no detailed description. The system diagrammatically represented in FIGURE 2 includes a winding 23 around strong magnets of the permanent type on each side of magnetic poles under each string so that differences in sound vibrations cause corresponding differences in electrical signals that are generated. Winding or inductance 23 is connected across variable resistance 24 which is actuated by knob 24a on the instrument to control volume. The sliding contact on resistance 24 is connected through condenser 25 to the sliding contact of variable resistance 26, which is actuated by knob 26a on the instrument to control tone quality. In the other transducer circuit 21', knob 27a actuates variable resistance 27 for volume control and knob 28a actuates variable resistance 28 for tone control. Transducer circuit 21 is grounded at 29 and circuit 22' at 30. Switch 31, which is actuated by button 31a on the instrument, enables the performer to select the transducer 21 or 22 which he desires, and this switch may be designed to enable any number of transducers to be connected in series or parallel to obtain desired sound effects. Sliding connection or jack 32. was heretofore used for plugging in a cable leading to a speaker.
With my invention no external cable is plugged into the instrument, and it may be freely moved for distances of about 2 to 25 feet or more. Internal connectors 33 and 33 lead from the transducer system A through an opening B in the instrument itself to my improved transmitterpower assembly C, which is in a part of the instrument remote from the transducer system to avoid electrical disturbance and to facilitate physical control. The transmitter portion of the assembly is preferably atunnel diode circuit as will be hereinafter described. As shown in FIG. 1, the transmitter-power assembly is mounted with in the instrument under a plate above the fretted neck while the transducer system is under the so-called scratch plate at the lower part of the instrument when it is in playing position. The power source may be a battery, but it may alternatively be a receiver for transmitted electrical energy, the important feature being that I do not employ any external cable or connector leading from the instrument to a separate power source. The transmitterpower assembly is preferably shielded in any conventional manner to minimize frequency drift.
As for the tunnel diode circuit, conductors 33 and 33 are connected, preferably through an audio amplifier stage 34, to an oscillating circuit. Conductor 33 is connected through switch 35, battery 36 and resistance 37 to terminal point 38 and it is also connected to point 38 through resistance 39. Switch 35 is actuated by button 35a on the instrument. Connector 33' is connected to point 38 through condenser 40. Connector 33 leads to copper strip connector 41 and point 38 is connected to copper strip 42, a condenser 43 being connected between strips 4 2 and 41. A tunnel diode 44 is connected to strip 42 and to another strip 45, a variable condenser 46 (actuated by knob 46a on the instrument) being connected between conductor strips 41 and 45. An inductance 47 is connected between the ends of conductor strips 41 and 45, said inductance 47 cooperating with variable condenser 46 to form a so-called tank circuit. The transmitting antenna is connected to conductor strip 45. In this example the copper strips are secured to a plastic base sheet, they are about wide and very thin. The values of the respective elements in the specific example are as follows:
Element: Value Battery 36 1.5 volt mercury cell. Resistance 37 270 ohms.
Resistance 39 22 ohms.
Condenser 40 50 microfarads.
Condenser 43 0.001 microfarad.
Tunnel diode 44- G.E. 1N2939 (see tunnel diode manual).
Variable condenser 46-"- 1.5 micromicrofarads to 5.0 mmf.
Inductance 47 0.2 micro henrys.
Antenna 4-8 4.75 inches long.
The operation of the invention should be obvious from the foregoing description. The strings of the guitar are manually tuned as usual. Switch 311 is placed in the desired position by manipulating button 31a. Switch 35 is closed by means of button 35a. Knob 46a is set to position variable condenser 46 and to obtain the desired frequency, which may for example be about 70 to 117 mc./ sec., e.g. 107 n1c./ sec. Volume and tone quality are adjusted by positioning knobs 24a and 26a and/or 27a and 28a. Thenceforth the instrument may be handled and played as if it were an ordinary non-electronic guitar, but with a wide range of volume and tonal effects not attainable with a simple acoustical instrument. The signal transmitted from antenna 48 is picked up by the antennae 49 and 50 of receiver-speaker assembly 51 which is usually also provided with one or more amplifying stages and which is tuned to the frequency of the transmitter. The transmitter circuit may be tuned to a frequency in the conventional radio broadcasting band (550 to 1700 kc./sec.) so that the transmitted signals may be picked up by an ordinary radio and the sound may come from the speaker thereof.
I have discovered that the tonal effects obtainable by use of my transmitter are unexpectedly quite different under some conditions than those obtained when the instrument is connected to the speaker with a cable. When the audio amplifier stage is used with the transmitting circuit, it may be manually controlled by one or more knobs (not shown) on the instrument, thus giving the performer even more latitude with respect to tone volume and sound effects.
While the invention has been described by reference to a specific example, it is not limited thereto. Other more simple or more elaborate circuits may be used either in the transducer system or in the transmitting circuit. The transmitting antenna may be encased in a shielding element. The values and arrangement of the various elements may vary Widely as will be apparent from the above description to those skilled in the art.
1. An electronic guitar having a fretted neck; a power source, a variable frequency transmitter circuit, a transducer system and connections from the transducer system and the power source to the transmitter circuit, all carried in said guitar; and a transmitting antenna connected tothe transmitter circuit and mounted about 2 to 3 inches above said fretted neck and substantially parallel thereto so that when the guitar is played by a performer, the antenna is protected by the timed left arm of said performer from external physical contacts and electrical disturbance and drift, and signals may be broadcast from said antenna to a receiver spaced therefrom and without any electrical connector therebetween.
2. In combination, a portable, electronic, stringed, musical instrument having a neck adapted to be held by a performers left hand curved under and in front of it and having strings adapted to be vibrated by the thumb and fingers of the performers right hand; a power source, a variable frequency transmitter circuit, a transducer system and connections from the transducer system and the power source to the transmitter circuit, all carried in said musical instrument; and a transmitting antenna connected to the transmitter circuit and carried by the musical instrument about 2 to 3 inches above said neck so that it is in shielded position when the instrument is being played and so that it is protected from external physical contacts and from electrical disturbance and drift, whereby signals may be broadcast from said antenna to a receiver spaced therefrom and in tune with the frequency of said transmitter circuit Without any electrical connector between said musical instrument and said receiver.
References Cited in the file of this patent UNITED STATES PATENTS 2,488,927 Owens Nov. 22, 1949 FOREIGN PATENTS 1,160,069 France July 7, 1958 OTHER REFERENCES The Dynatone, Radio-Craft, January 1939, 2 pages, beginning on page 398.
Transistorized Ukulele, Radio Electronics, February 1954, pages 30-32.
Electronic Banjo, Popular Electronics, February 1956, pages 6 l63, 117 and 118.
General Electric Transistor Manual, 5th ed., Oct. 28, 1960, pages 163 and 164.
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|U.S. Classification||84/723, 455/128, 455/95, 984/369, 84/267|
|International Classification||G10H3/18, H04B1/034|
|Cooperative Classification||G10H3/182, G10H2240/211, H04B1/034|
|European Classification||H04B1/034, G10H3/18C|