US 3825666 A
Apparatus for generating a signal from an electrical instrument includes two transistor amplifiers adapted to receive electrical signals from a transducer in the vicinity of the vibrations from the instrument. The amplified signal is applied to an oscillator which includes a radiating element to frequency modulate the oscillator signal with the amplified signal. The oscillator signal is radiated, detected, amplified, and reproduced by a nearby fm radio.
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Description (OCR text may contain errors)
United States Patent [191 Jaggers July 23, 1974  APPARATUS FOR TRANSMITTING THE 3,080,785 3/1963 Evans 84/].16
OUTPUT OF A MUSICAL INSTRUMENT g g on reau eta. FOR AMPLIFICATION 3,296,916 l/l967 Palmer  Inventor: H. Dane Jaggers, Ozark, Ark. 3,308,403 3/1967 Kubota et a1. .0 331/177 R A t'  Sqlgnee gi corpora Tulsa Primary ExaminerRichard B. Wilkinson Assistant ExaminerU. Weldon Flledi J ly 0, 1973 Attorney, Agent, or Firm-William S. Dorman  Appl. No.: 383,529
 ABSTRACT I 52 US. Cl 84/1.0l, 84/l.16, 331/108 R Apparatus for generating a signal from an electrical  Int. Cl. GlOh 1/00 instrument includes two transistor amplifiers adaPted [53 Field f Search H 34 11 1 1 14 15; to receive electrical signals from a transducer in the 331 1031 103 A 10 B, 103 C, 103 I) vicinity of the vibrations from the instrument. The am- 7 77 R, 77 v; 332 17 1 A 1 plified signal is applied to an oscillator which includes 330 12 1 a radiating element to frequency modulate the oscillator signal with the amplified signal. The oscillator sig- 5 R f s Cited nal is radiated, detected, amplified, and reproduced by UNITED STATES PATENTS a fm 2,864,903 l2/l95fl Becking'et al..... .I 330/16 1 Claim, 1 Drawing Figure or A MUSICAL INSTRUMENT FOR AMPLIFICATION BACKGROUND OF THE INVENTION 1. Field of the Invention I This invention relates to circuits for use with musical instruments, and more particularly to a circuit for transmitting the output of a musical instrument for amplification.
2. Description of the Prior Art Of current popularity for use with musical instru- APPARATUS FOR TRANSMITTING THE OUTPUT to the oscillator to modulate the oscillator signal with Y the amplified electrical signal, and the frequency mod ments, and particularly; for use withguitars and similar such stringed instruments, are amplifier systems to which the vibrations of the instrument, transduced into electrical signals, 'are applied. Many commercially for the single purpose of receiving electrical signals for one or more guitars or other such instruments foramplification and sound distribution. Additionally, ordi narily the guitars are necessarily physically connected to the amplifiers used by a cord, which limits the free dom of movement of the player or which requires the players keeping track of the cord and moving from place to place.
SUMMARY or THE INVENTION In light of the above, it is, therefore, an object of the invention to provide a portable unit for use with a musical instrument for transmitting the musical vibrations thereof to a nearby radio'for detection and amplifica-.
It is another object of the invention to provide a portable vibration transmitting circuit for use with a guitar having an electrical pickup head to obviate the necessity of connection to an amplifier. 1 It is still another object of the invention to provide a transistorized unitwhich is portableand can be carried upon the musical instrument for transmitting the vibrations thereof to anearby radio for detection and amplification.
It is yet another object of the invention to provide an electrical circuit which can be mounted onto and carried by a guitar to generate a frequency modulated signal of the electrical signal of the guitar pickup and for radiating the signal through the air to a nearby fm receiver for detection and amplification. v
These and other objects, features, and advantages will become apparent to those skilled in the art from the following detailed description when read in conjunction with the accompanying drawings and claims.
a The invention, in its broad aspect, presents a portable transmitting unit .for use with a musical instrument, such as a guitar or the like, which includes means for connection to a vibration detecting electrical trans ducer'in the vicinity of the musical instrument. Means are provided for amplifying the electrical signal of the transducer, and an oscillator means is provided having an oscillation signal, the frequency of which is within thefrequency detection range of a nearby radio. Means are included for applying the amplified electrical signal I DETAILED DESCRIPTION OF THE PREFERRED coupling capacitor '31. Resistors vided to the emitter and collector, respectively, for biulatedsignalis applied to a radiating means included in the oscillator for radiating the modulated signal into the air to be thereby reproduced by the nearby radio.
BRIEF DESCRIPTION OF THE DRAWING The invention -is illustrated in the accompanying drawing in which the sole figure illustratesan electrical schematic diagram-of the circuit, in accordance with the invention, for use in generating a frequency modulated signal from a guitar for detection, amplification and reproduction by a nearby fm radio.
EMBODIMENTS The apparatus, illustrated in the accompanying drawing, includes a circuit, generally denoted by the reference numeral 10, for producingv a signal frequency modulated by a signal representing the musical vibrations of a musical instrument, such as a guitar 11. The frequency modulated signal is detected by a nearby fm radio 12 and therein amplified and applied to a speaker 13 tobe reproduced. In particular, themusical vibrations from the guitar 11 'transduced into electrical signals by a guitar pickup 15 mounted on the guitar ina manner well known in the art are then conducted by wires 17 for connection to the circuit 10 by a plug or other electrical connection means, denoted generally by the arrows 19 and'20.
The circuit 10 includes three general sections or stages, first and second amplifier sections 25 and 26, respectively, (ordinarily since the electrical output from transducers commonly used with musical instruments is at a relatively low level, at least two amplification stages are preferably employed to bring the signal to a suitable level for transmission) and an oscillator section 27. The first'amplifier stage 25 includes a transistor 30 of p-n-p conductivity type, to the base of which the signal from the pickup 15 is applied via a v36 and 37'are proasing and loading the transistor 30.
The second amplifier stage 26 includes a transistor 35 of p-n-p conductivity type to the emitter of which the input signal from the pickup 15 is applied by a resistor 33. The signal developed at the collector of the transistor 30 is conducted by line 40 to the base of the transistor 35, and the signal developed across the emitter resistor 36 of the first amplifier stage transistor 30 is coupled by a capacitor 41 in series with the parallel combination of a resistor 42 and capacitor 43 to the collector of the second amplifier stage transistor 35.
Resistors 45 and 46 are provided, respectively, to the forms an oscillator circuit. A voltage divider including resistors 56 and 57 properly maintains the potential of the base of the transistor with respect to the other transistor elements, and a capacitor 58 provides a bypass path in parallel with the resistor 57. The collector of the transistor 55 is connected to a frequency deter-' mining tank circuit including a capacitor 60 and a variable inductor 61, the variable inductor 61 functioning as the radiating element from the oscillator section 27. If desired, an additional signal radiating element (not shown) can be coupled to the variable inductor 61, such as by a tap or by other well known manners, to increase the range of signal transmission. A capacitor 62 interconnects the collector and emitter to effect the frequency modulation of the oscillator signal with the amplified guitar pickup signal, and a biasing resistor 64 is provided in connection with the emitter of the transistor 55.
Finally,a battery 65 provides the source of electrical energy to the first two amplifier stages 25 and 26 and the oscillator stage 27, and a capacitor 66 is connected in parallel with the battery 65 to isolate it from the alternating currents encountered in the circuit 10.
By way of example, specific'components which can be used in the circuit are as follows:
Transistors 30 ECG102A 35 ECGl02A 55 ECG160 Resistors 33 68K ohms 36 330 ohms 37 30K ohms 42 K ohms 45 1,000 ohms 46 10K ohms '56 15K ohms 57 5K ohmsv 64 1,000 ohms Capacitors 31 5. mfd 41 0.02 mfd 43 0.005 mfd 48 0.30 mfd 50 5. mfd 58 0.00l'mfd 60 12. mfd 62 3. mfd 66 82. mfd
It should be noted that although the circuit 10 has been illustrated and described as including transistors I of p-n-p conductivity type,.transistors of other conducamplifier stage transistors 30 and 35. The signal at the first amplifier stage transistor is also coupled directly by line 40 to the base and through the capacitor 41 and capacitor 43 resistor 42 network to the emitter of the second stage transistor 35. The output signal of the second stage transistor 35 is applied to the base of the oscillation transistor 55 to frequency modulate the oscillation signal thereof.
The oscillation signal is radiated by the inductor 61 to be received by an antenna 70 of a nearby fm radio or tuner 12. The received signal is then amplified by the amplifier of the radio, or an amplifier in conjunction with the tuner, and applied to a speaker 13.
Since the signal radiated from the inductor 61 is within the range of detection of an fm radio, the inductor 61 is preferably variable to enable the oscillation signal to be changed in the event that the signal is detected on the same frequency as, for example, a commercial radio station in the particular locality which the circuit 10 is used. Thus, in such event, the inductor 61 can be tuned to a frequency within the fm frequency band in the particular locality at which no preexisting signals exist.
The circuit described thus enables a guitar or like musical instrument to be operated without requirement for expensive amplification systems for the sole use of the individual instrument. The instrument, when used in connection with the circuit 10, can be used with a preexisting fm radio or hi-fidelity system to take advantage of the amplifiers of such a system in place of the specific amplifier for the guitar or such instrumentv Furthermore, the circuit 10 can easily be fabricated on a printed circuit board, or other miniaturized electronic assembly, and can be made conveniently as small as practical. This facilitates mounting the circuit- 10 upon the instrument, for example, concealed within the soundbox of the guitar 11.
Although the invention has been described and illustrated with a certain degree of particularity, it is understood that the present disclosureis made only by way of example and that numerous changes in the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.
What is claimed is:
1. A portable transmitting unit for use with a musical instrument comprising: a vibration detecting electrical transducer mounted on said instrument; a first amplifier stage including a first transistor of p-n-p conductivity type,-a first capacitor connected between said transducer and the base of said first transistor, a first bias resistor connected between ground and the emitter of said first transistor, a source of do energy one side of which is connected to ground, a second bias resistor connected between the ungrounded side of said source of d.c. energy and the collector of said first transistor; a second amplifier stage including a second transistor of the p-n-p conductivity type, a first coupling resistor connected between the base of said first transistor and the emitter of said second transistor, a second capacitor connected at one side to the emitter of said first transistor, a third capacitor and a second coupling resistor connected in parallel, the parallel connection of said second coupling resistor and said third capacitor being connected between the other side of said second capacitor and the collector of said second transistor, means directly connecting the collector of said first transistor to the base of said second transistor, a third bias resistor connected between ground and the emitter of said second transistor, a fourth capacitor connected in parallel across said third bias resistor and constitutingian r-f bypass for said second transistor, a fourth bias resistor connected between the collector of said second transistor and the ungrounded side of said source of d.c. energy; an oscillator and transmitter stage includfifth bias resistor connected between the ungrounded side of said source of do. energy'and the base of said third transistor, a sixth bias resistor connected between ground and the base of said third transistor, a fifth capacitor connected in parallel across said sixth bias resistor, a sixth capacitor connected between the collector of said second transistor and the base of said third transistor, a seventh bias resistor connected between ground and the emitter of said third transistor, a tank circuit consisting of a seventh capacitor. and a variable inductor connected in parallel and connected between the ungrounded side of said source of do. energy and the collector of said third transistor, said tank circuit functioning to cause said oscillator and transmitter stage to provide an oscillation signal the frequency of which is within the frequency reception band of a nearby f-m radio receiver, said variable inductor also constituting a radiating means for radiating said oscillation signal into the air, an eighth capacitor connected between the collector and emitter of said third transistor to effect frequency modulation of said oscillation signal with the amplified signal from said transducer; a
ninth capacitor connected in parallel across said source of do. energy and constituting an a.c. bypass for said source of do. energy; whereby the radiated oscillation signal is detected and the vibrations of said musical instrument are reproduced and amplified by said f-m I radio receiver.