Device for attenuating noise in electrical apparatus

The present invention relates to an attenuator for reducing noise and distortion, preferably in the audio frequency range. Briefly stated, the present invention is comprised of two wedge shapes in one block with two axially opposing leads connected to the wedge shape midway along the line formed by the intersection of two adjacent sides. The leads are preferably bent at 90.degree. and connected to attenuator conductive strips contained on a circuit board. The attenuator conductive strips on the circuit board are preferably at 90.degree. with respect to parallel conductive strips connected to a speaker or the like. The entire attenuator structure is preferably covered with an insulative or dielectric material.

BACKGROUND OF THE INVENTION 
This invention relates, generally, to the reduction of noise in electrical 
circuits and more particularly to a device for reducing/suppressing noise 
in electrical circuits such as audio circuits. 
Since the inception of audio electronics, i.e. radios, stereos, tapeplayers 
and the like, distortion or unwanted sound in the form of noise has been a 
constant problem and consideration. The problems are complex and have 
hereto been difficult to solve since noise is generally the result of a 
cumulative affect in the circuit, although some portions of any apparatus 
may present more problems than others. 
Solving this problem has been somewhat of an evolutionary process which has 
encompassed better circuit design, improved component layout, higher 
quality components and the like. Some approaches try to minimize the 
production of noise while others attempt to supress noise downstream of 
its production. Some schemes attempt to use parametric amplifiers, 
shielding or filters in order to fulfill the goal of noise free sound 
reproduction. 
However, while great progress has been made, the production of noise is 
inevitable since no component, circuit or scheme is ideal. 
Further, many schemes are relatively expensive to design, manufacture and 
install and are also generally not amenable to retrofitting. Also, since 
these schemes utilize active components or directly interact with active 
components, they themselves are subject to the production of noise. 
Additionally, each solution is inherently unique to each application. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to produce an attenuating device 
which is inexpensive to manufacture and install. It is another object of 
the present invention to produce a device which does not have to be 
designed for each individual application. It is still a further object of 
the present invention to produce a device which is passive and does not 
require that it be directly interconnected with active components. 
Another object of the present invention is to produce a device which is 
retrofittable to existing circuits as well as being useable over a wide 
variety of situations. 
It is yet another object of the present invention to produce an electrical 
noise attenuator for use in an electrical circuit having signal carrying 
conductors therein, comprising an electrically conductive attenuator block 
having at least four planar sides and at least six edges, each edge being 
formed by the intersection of any two planar sides, a first electrically 
conductive wire having a first end and a second end, the first end 
connected to a first edge of the attenuator block, a second electrically 
conductive wire having a first end and a second end, the first end axially 
spaced from the first end of the first conductive wire and being connected 
to a second edge of the attenuator block, a first attenuator conductive 
strip connected to the second end of the first electrically conductive 
wire, and a second attenuator conductive strip connected to the second end 
of the second electrically conductive wire, the second attenuator 
conductive strip axially disposed from the first attenuator conductive 
strip, wherein the first and the second attenuator conductive strips are 
disposed adjacent the signal carrying conductors contained in the 
electrical circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1, an illustration which is representative of use of 
the present invention may be seen. It is to be understood that the present 
invention is preferably used to attenuate noise in audio frequency 
circuits, although noise attenuating for other ranges or frequencies can 
and may be utilized without departing from the spirit and scope of the 
present invention. It is also contemplated that the present invention is 
preferably used adjacent the final output amplifier in audio apparatus. 
This audio apparatus may include, for example, radios, audio and video 
tape players, stereos systems and the like. However, the present invention 
may be utilized in earlier stages of any amplification network. 
Shown, is a circuit board 10 which may be part of a larger circuit board. 
Conductive strips 12 which are traces on circuit board 10 are placed 
adjacent each other and thereafter connected to speaker 14. Also disclosed 
on circuit board 10 is attenuator 16 of the present invention. Attenuator 
16 is connected to attenuator conductive strips 18 which are preferably 
perpendicular to and near but not in contact with conductive strips 12. 
The attenuator 16 is generally comprised of a three dimensional four sided 
polygon wherein each of the sides is preferably of equal size and shape. 
Lead wires 22 emanate from attenuator block 20 and are connected to 
attenuator conductive strips 18. The lead wires 22 are connected to 
attenuator block 20 so as to be axially opposed from each other and are 
connected at first edge 30 and second edge 32 of attenuator block 20. 
It has been found that the orientation shown in FIG. 1 provides for optimum 
noise attenuation. The orientation of the attenuator 16 should preferably 
be perpendicular to conductive strips 12, although other angles can be 
used but will generally result in lower noise attenuation than the 
orientation shown. Conductive strips 12 should preferably be parallel to 
each other and should pass under attenuator 16. It has been observed that 
the height of attenuator 16 from circuit board 10 is not critical although 
a distance which is more than two or three orders of magnitude of the 
height of attenuator block 20 does decrease the benefits of attenuator 16. 
While the dimensions are not critical, it has been found that optimum 
results are obtained when they are within the mentioned tolerances. 
Further, and as mentioned, it is preferred that conductive strips 12 carry 
the audio frequency components of a sound signal. By use of attenuator 16 
in the configuration shown, noise and distortion present at speaker 14 is 
greatly reduced as compared to the same apparatus prior to use of 
attenuator 16. 
Referring now to FIG. 2 a cross-sectional view taken through FIG. 1 is 
shown. It may now be seen how lead wires 22 are disposed midway along each 
corner or edge of attenuator block 20. Also evident is how almost the 
entire attenuator apparatus 16 is covered by an insulator/dielectric 26 
which covers core 24 of attenuator block 20 as well as conductive wires 28 
of lead wires 22. It has been found that optimum results can be obtained 
by insulating the entire outer area as close to conductive strips 18 as is 
possible. It has further been found that the conductive wires 28 should 
preferably emanate from the core 24 in right angles thereto. The 
conductive wires 28 may be of any suitable conductive material and are 
preferably copper. The core 24 is preferably lead although any suitable 
conductive material such as, for example, lead, copper, steel, aluminum or 
the like may be used. It has been found that it also not required that 
conductive wires 28 be of the same material as the core 24. It is 
preferable but not required that lead wires 22 be bent at right angles for 
presentation to conductive strips 18. Additionally, it is preferred that 
conductive wires 28 pass through circuit board 10. The length which they 
should extend through circuit board 10 has been found to be nonthrough 
critical and is typically the length of other leads on printed circuit 
boards. It is not required that the attenuator block be centrally disposed 
between the conductive strips 18 as is shown in FIG. 2 and it is similarly 
non-critical that conductive block 20 be centrally disposed over 
conductive strip 12. However, it has been found that "symmetry" of the 
orientation of the attenuator 16, with respect to conductive strips 12, 
18, although non-critical, is sensitive to orders of magnitude of 
deviation. 
Referring now to FIGS. 3A, 3B and FIGS. 4, 4A-4D, the orientation of the 
different sides of the attenuator block may be more clearly seen. It has 
been found that optimum results are generally obtained when each side of 
block 20 is equal. Further, it has been found that A and A' are preferably 
45.degree. which therefore dictates that angle B and B' are 90.degree.. 
Similarly, angles C and C' should also be 90.degree.. Further, lead wires 
22 are preferably placed on an edge between two adjacent sides and midway 
along the length of the edge, with one lead wire axially opposed, that is, 
180.degree. from the remaining lead wire. However, it is to be understood 
the lead wires 22 do not have to be exactly in alignment as mentioned or 
that attenuator block 20 have equal sides for the present invention to 
work. It has been observed however that the angular and spacial 
relationships mentioned offer optimum results and that deviation therefrom 
will result in lower perfromance. It is also been observed that the use of 
a four sided polygon for an attenuator block 20 is preferred since 
polygons having other numbers of sides, although workable, do not seem to 
perform as well. 
It is to be understood that many variations in the present invention may be 
practiced without departing from the spirit and scope of the present 
invention. For example, substrates other than printed circuit boards may 
be utilized while wires instead of attenuator conductor strips may be 
used. Further, bending of the lead wires can be made in a different manner 
while the insulation disposed on the attenuator need not extend fully to 
the attenuator conductive strips. 
Although the present invention has been described in connection with a 
preferred embodiment thereof, many other variations and modifications will 
now become apparent to those skilled in the art. It is preferred, 
therefore, that the present invention not be limited by the specific 
disclosure herein, but only by the appended claims.