GB2236643A

GB2236643A - Radio transmitter for musical instruments

Info

Publication number: GB2236643A
Application number: GB8921885A
Authority: GB
Inventors: Dudley Lloyd Rumfitt
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-09-28
Filing date: 1989-09-28
Publication date: 1991-04-10
Anticipated expiration: 2009-09-28
Also published as: GB2236643B; GB8921885D0

Abstract

The transmitter is arranged as one complete unit supported by a plug 16 entering the audio output socket of a musical instrument. Plug 16 is attached by a flexible rubber mounting 16A to one end of an elongate body 15 enclosing amplifying, r.f. oscillating and modulating circuits, and a substantially rigid, but elastically deformable antenna 17 is removably screwed to the opposite end of body 15 by a connector 18. Screws 19, 20 are provided for adjustment of the amplifier gain and the r.f. oscillator frequency, and a microswitch 21 disconnects a battery in body 15 from the circuits therein when the plug 16 is removed from the instrument's socket. Two channels my be modulated onto a common r.f. carrier for stereo operation. <IMAGE>

Description

RADIO TRANSMITTER FOR MUSICAL INSTRUMENTS BACKGROUND OF THE INVENTION Many modern musical instruments cannot produce a musical output by conventional acoustic means and are, instead, arranged to produce an electrical output which is then supplied to an amplifier. Thus, in order for the signal to be transferred from the instrument to the amplifier, mixer or similar apparatus, a transmission path must be provided, usually in the form of a coaxial lead with a respective 3.5mm jack plug connected to either end.

A problem encountered with mechanical leads, particulariy in an on-stage environment, is that they tend to restrict movement of the musician, who must take care to ensure that an electrical connection is maintained between his instrument and the amplification system at all times. Furthermore, movement of the lead tends to cause damage, particularly at the junction between the wire and the jack plugs. To overcome this problem, it is known to use a radio link between the instrument and the amplifying system, wherein, the audio frequency output from the musical instrument is amplified, modulated and then transmitted to a suitable receiver connected to the amplification system.The most common application for such devices is with electric guitars and electric bass guitars wherein a transmitter box, attached to a part of the guitarist's attire, is connected to the guitar output by means of a lead, resembling the conventional type of lead for connecting a guitar to an amplifier.

Another form of radio link, in audio applications, is that used in radio microphones, wherein, the complete assembly is packaged in the shell of a microphone and a short wire extending from the microphone is used as an aerial, which in turn transmits a signal to the receiver, positioned near the amplification system.

It is an object of the present invention to provide an improved radio transmitter for musical instruments. In particular, it is an object of the present invention to provide a radio transmitter for musical instruments wherein, without adapting the instrument in any way, the transmitter is connectable to the instrument without requiring trailing wires leading to additional circuitry supported by the musician.

SUMMARY OF THE INVENTION According to the present invention, there is provided a radio transmitter for musical instruments having an output socket for an amplifier lead, comprising an elongate body enclosing amplifying and modulating circuits, a plug extending from a first end of said elongate body and arranged to engage with an output socket of a musical instrument and a substantially rigid aerial extending from the end of said elongate body opposite to said first end, wherein an audio-frequency electrical signal is supplied to said amplifier and modulator circuit via said plug and a modulator output from said amplifier and modulator circuit is supplied to said aerial.

Thus, in accordance with the present invention, the complete assembly of amplifier, modulator and aerial are supported by the plug extending into the musical instrument.

Preferably, the overall length of the device is less than 30cm and the rigid aerial may be elastically deformable and, preferably, disconnectable from said body for storage purposes.

In a preferred embodiment, adjusting means are provided for adjusting the properties of said amplifier or said modulator.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a radio transmitter for a musical instrument including a plug for insertion into the musical instrument, a central body enclosing amplifying and modulating circuitry, and an aerial; and, Figure 2 shows a circuit diagram of the amplifying and modulating circuitry contained within the device housing.

DESCRIPTION OF THE PREFERRED EMBODIMENT A radio transmitter for a musical instrument is shown in Figure 1, in which ampliiaing and modulating circuitry is housed in an elongate body 15. Extending from the right end of said body, as shown in the Figure, is a standard jack plug 16 arranged to engage with a cooperating socket forming part of a musical instrument. The jack plug 16 is supported to the elongate body 15 by a flexible rubber mounting 16A, allowing the body to flex, when pressure is applied thereto, without causing damage. At the opposite end, the left end as shown in the Figure, an aerial 17 extends from the elongate body and is arranged to transmit modulated signals to a suitable receiver, not shown.The aerial, although rigid, is elastically flexible and similar to the type commonly found on motor cars, but short enough to give a total length to the device which is less than 30cm.

To facilitate storage of the device, the aerial is connected to the elongate body by means of a plug and socket arrangement 18, of the type commonly used for connecting coaxial cables etc. The gain of the amplifier may be adjusted by a first screw 19 and the frequency of the modulator may be adjusted by a smaller screw 20, each engagable through the elongate body. The body also has a microswitch with an on/off lever 21 extending in parallel with the jack plug, wherein, the amplifier and modulator only receive power from batteries stored within the housing when the device is actually engaged into a musical instrument.

An example of a suitable electronic circuit, for containment within the elongate body, is detailed in Figure 2. An input signal from the jack plug 16 is supplied to the gate of a field effect transistor 25, such as type 25C2058 TO92, via a potentiometer 26. Potentiometer 26 controls the output gain and is adjusted by screw 19. The field effect transistor 25 is the only active component and provides both modulating and amplifying functions. A radio-frequency signal is obtained from a combination of an inductor 27 and several capacitors as shown in the Figure. Capacitor 28 has variable capacitants and is adjusted by screw 20 to vary the output frequency.

The circuit detailed in Figure 2 merely illustrates an example of a suitable circuit and it is envisaged that production units would include sophisticated intergrated circuits, of the type well known to practioners in the art.

The unit may be used with a purpose build receiver or, alternatively, a conventional radio set may be used, with both transmitter and receiver tuned to a free channel. In this way the device may be used in domestic environments, enabling a musician to practice without using dedicated amplification systems. On stage, the device has the advantage of not requiring any link to the musicians body, allowing instruments to be removed easily. Several devices may be used simultaneously, operating at different frequencies. The circuit could also operate in stereo, being fitted with a stereo jack plug and modulating two channels onto a common carrier, as used in conventional FM broadcasting.

Claims

1. A radio transmitter for musical instruments, having an output socket for an amplifier lead, said transmitter comprising an elongate body enclosing ampWing and modulating circuits, a plug extending from a first end of said elongate body and arranged to engage with an output socket of a musical instrument, and a substantially rigid aerial extending from the end of said elongate body opposite to said first end, wherein an audio-frequency electrical signal is supplied to said amplifying and modulating circuit via said plug, and a modulated output from said amplifying and modulating circuit is supplied to said aerial.

2. A radio transmitter according to claim 1, wherein the overall length of said device is less than 30cm.

3. A radio transmitter according to claim 1 or claim 2, wherein said rigid aerial is elastically deformable.

4. A radio transmitter according to any preceding claim, wherein said aerial is disconnectable from said body for storage purposes.

5. A radio transmitter according to any preceding claim, wherein said plug is connected to said body via a flexible mounting.

6. A radio transmitter according to any preceding claim, including a switch for disconnecting power supplied to said circuit on removal of the transmitter from said musical instrument.

6. A radio transmitter according to claim 1, including accessible adjusting means for adjusting the properties of said amplifier or said modulator.

7. A radio transmitter substantially as herein described with reference to the accompanying Figures.