U.S. patent application number 11/670872 was filed with the patent office on 2008-08-07 for outlet cover with barrier wall.
Invention is credited to Joseph W. Wimberly.
Application Number | 20080185166 11/670872 |
Document ID | / |
Family ID | 39670755 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080185166 |
Kind Code |
A1 |
Wimberly; Joseph W. |
August 7, 2008 |
OUTLET COVER WITH BARRIER WALL
Abstract
An outlet cover with barrier wall, the cover for an outlet box
mounted in a building wall including an outer wall with an outer
opening formed in the outer wall; a surrounding wall integrally
joined to an outer periphery of the outer wall and extending
substantially normal to the outer wall; a barrier wall integrally
joined to an inner periphery of the outer wall at an edge of the
outer opening and extending substantially normal to the outer wall,
the barrier wall forming an inner opening opposite the outer
opening to meet the outlet box; and an attaching flange integrally
joined to an inner end of the surrounding wall for being placed
against the building wall, the attaching flange being a continuous
flange about an exterior periphery of the surrounding wall.
Inventors: |
Wimberly; Joseph W.;
(Lombard, IL) |
Correspondence
Address: |
CARDINAL LAW GROUP;Suite 2000
1603 Orrington Avenue
Evanston
IL
60201
US
|
Family ID: |
39670755 |
Appl. No.: |
11/670872 |
Filed: |
February 2, 2007 |
Current U.S.
Class: |
174/66 |
Current CPC
Class: |
H02G 3/14 20130101; Y10T
29/49169 20150115 |
Class at
Publication: |
174/66 |
International
Class: |
H05K 5/03 20060101
H05K005/03 |
Claims
1. A cover for an outlet box mounted in a building wall,
comprising: an outer wall with an outer opening formed in the outer
wall; a surrounding wall integrally joined to an outer periphery of
the outer wall and extending substantially normal to the outer
wall; a barrier wall integrally joined to an inner periphery of the
outer wall at an edge of the outer opening and extending
substantially normal to the outer wall, the barrier wall forming an
inner opening opposite the outer opening to meet the outlet box;
and an attaching flange integrally joined to an inner end of the
surrounding wall for being placed against the building wall, the
attaching flange being a continuous flange about an exterior
periphery of the surrounding wall.
2. The cover of claim 1 wherein the cover is unitary and made of
plastic.
3. The cover of claim 1 wherein the surrounding wall and the
barrier wall are of substantially equal height.
4. The cover of claim 1 wherein the outer wall and the attaching
flange are parallel.
5. The cover of claim 1 wherein the shape of the inner opening is
selected from the group of shapes consisting of round, rectangular,
and square.
6. The cover of claim 1 wherein the barrier wall comprises a round
portion and a rectangular portion.
7. The cover of claim 1 wherein the outer wall has a removable
opening panel across the outer opening.
8. The cover of claim 7 wherein the removable opening panel forms a
cutting aperture.
9. The cover of claim 1 further comprising a trim ring, the trim
ring having a ring wall and ring extending flange substantially
normal to the ring wall, wherein the ring wall is slideable about
the surrounding wall.
10. The cover of claim 9 wherein the ring wall and the surrounding
wall have complementary ridges and grooves.
11. The cover of claim 10 wherein the grooves associated with one
of the ridges are spaced apart to provide a first distance between
the ring extending flange and the attaching flange when a first
groove is locked on the one of the ridges and a second distance
between the ring extending flange and the attaching flange when a
second groove is locked on the one of the ridges.
12. The cover of claim 9 wherein the ring extending flange is a
first ring extending flange, and the trim ring further comprises a
second ring extending flange substantially normal to the ring wall
and on an end of the ring wall opposite the first ring extending
flange.
13. A system of an outlet box mounted in a building wall, the
outlet box having a front opening and the building wall being
covered with siding, comprising: an outer wall with an outer
opening formed in the outer wall; a surrounding wall integrally
joined to an outer periphery of the outer wall and extending
substantially normal to the outer wall; a barrier wall integrally
joined to an inner periphery of the outer wall at an edge of the
outer opening and extending substantially normal to the outer wall,
the barrier wall forming an inner opening opposite the outer
opening to meet the outlet box; and an attaching flange integrally
joined to an inner end of the surrounding wall for being placed
against the building wall, the attaching flange being a continuous
flange about an exterior periphery of the surrounding wall; wherein
the siding overlaps the attaching flange.
14. The system of claim 13 wherein the barrier wall comprises a
round portion and a rectangular portion.
15. The system of claim 13 wherein the outer wall has a removable
opening panel across the outer opening.
16. The system of claim 15 wherein the removable opening panel
forms a cutting aperture.
17. The system of claim 13 further comprising a trim ring, the trim
ring having a ring wall and ring extending flange substantially
normal to the ring wall, wherein the ring wall is slideable about
the surrounding wall, wherein the siding is disposed between the
ring extending flange and the attaching flange.
18-21. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to outlet covers, and more
specifically to outlet covers with a barrier wall.
[0002] Electric outlet boxes are provided in buildings to permit
connection of decorative light fixtures and exterior outlets on the
outside of the buildings. The outlet boxes are often installed in
the building wall before siding or other exterior covering is
installed. The electrician typically installs the outlet box with
its outer edge flush with the building wall and the decorative
light fixture is installed later, usually after the siding has been
installed. An outlet cover is required to make the transition
between the decorative light fixture and the outlet box and to seal
around the outlet box.
[0003] The present designs of outlet covers fail to solve a number
of problems. The outlet cover must provide a weather seal around
the outlet box to avoid water leakage into the building and energy
loss from the building. The outlet cover must provide electrical
isolation for the wiring passing through the outlet box to the
decorative light fixture or exterior outlet, so that a spark or hot
wire is contained. The outlet cover must be suitable for the shape
of the outlet box, i.e., the outlet cover must be tailored for or
suitable for use with rectangular or round outlet boxes. The outlet
cover must provide a secure platform for mounting the decorative
light fixture or exterior outlet, so that the decorative light
fixture or exterior outlet does not shift or twist.
[0004] It would be desirable to have an outlet cover with a barrier
wall that overcomes the above disadvantages.
SUMMARY OF THE INVENTION
[0005] One aspect of the invention provides a cover for an outlet
box mounted in a building wall, including an outer wall with an
outer opening formed in the outer wall; a surrounding wall
integrally joined to an outer periphery of the outer wall and
extending substantially normal to the outer wall; a barrier wall
integrally joined to an inner periphery of the outer wall at an
edge of the outer opening and extending substantially normal to the
outer wall, the barrier wall forming an inner opening opposite the
outer opening to meet the outlet box; and an attaching flange
integrally joined to an inner end of the surrounding wall for being
placed against the building wall, the attaching flange being a
continuous flange about an exterior periphery of the surrounding
wall.
[0006] Another aspect of the invention provides a system of an
outlet box mounted in a building wall, the outlet box having a
front opening and the building wall being covered with siding,
including an outer wall with an outer opening formed in the outer
wall; a surrounding wall integrally joined to an outer periphery of
the outer wall and extending substantially normal to the outer
wall; a barrier wall integrally joined to an inner periphery of the
outer wall at an edge of the outer opening and extending
substantially normal to the outer wall, the barrier wall forming an
inner opening opposite the outer opening to meet the outlet box;
and an attaching flange integrally joined to an inner end of the
surrounding wall for being placed against the building wall, the
attaching flange being a continuous flange about an exterior
periphery of the surrounding wall; wherein the siding overlaps the
attaching flange.
[0007] Yet another aspect of the invention provides a cover for an
outlet box having a front opening mounted in a building wall,
including an outer wall with an outer opening formed in the outer
wall; a surrounding wall integrally joined to an outer periphery of
the outer wall and extending substantially normal to the outer
wall; means for connecting a circumference of the front opening of
the outlet box with a circumference of the outer opening; and an
attaching flange integrally joined to an inner end of the
surrounding wall for being placed against the building wall, the
attaching flange being a continuous flange about an exterior
periphery of the surrounding wall.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of an exterior building wall
with a decorative light fixture mounted over the outlet box cover
made in accordance with the present invention;
[0009] FIG. 2 is an enlarged perspective view of the assembly of
FIG. 1, with the light fixture removed and with part of the
exterior siding broken away, each for clarity of disclosure;
[0010] FIG. 3 is a sectional view as seen generally from line 3-3
in FIG. 2;
[0011] FIG. 4 is a sectional view of the outlet box cover made in
accordance with the present invention as seen generally from line
3-3 in FIG. 2;
[0012] FIGS. 5-8 are back views of embodiments of outlet box covers
made in accordance with the present invention;
[0013] FIG. 9 is a fragmentary perspective view of an outlet box
cover made in accordance with the present invention with a trim
ring;
[0014] FIG. 10 is an enlarged fragmentary sectional detail view
taken substantially along the line II-II in FIG. 9;
[0015] FIG. 11 is a perspective view of a trim ring for an outlet
box cover made in accordance with the present invention; and
[0016] FIG. 12 is a side view of a trim ring and an outlet box
cover made in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] FIGS. 1-4, in which like elements share like reference
numbers, show various views of an outlet box cover made in
accordance with the present invention. FIG. 1 illustrates a
building wall 10 having exterior siding 12 and an electric light
fixture 14 mounted on the wall 10 over an outlet box cover 16. The
outlet box cover 16 overlies and hides an electric outlet box 18,
(FIG. 3), in part underlies the adjacent siding 12, and also
underlies the mounting flange 14a on the lighting fixture 14.
[0018] As is illustrated in FIG. 3, the wall 10 includes "two by
four" studs or other structural elements (only one at 19 being
shown) which run vertically and which are spaced apart
horizontally. Exterior wall board 20 is secured, as by nails (only
one at 22 being shown) or the like, to the outside of the spaced
studs 19; interior wall panel 24 is secured, by nails (only one at
25 being shown) or the like, to the inside of the studs 19; and
insulation 26 is located between the studs 19 and the exterior wall
board 20 and interior wall panel 24.
[0019] The outlet box 18 generally includes opposed pairs of
parallel walls 28 and 30 and a rear wall 32 forming a rigid
structure with one front opening 35. Flanges 34 inturned from the
forward edges of the walls 28 and/or 30 and having threaded taps to
receive screws or bolts provide for the ready securement of an
electric outlet and/or a cover plate (neither being shown) or the
fixture flange 14a. The outlet box 18 itself is secured by a
bracket 36 and nail 38 to the stud 19 in a manner so that the
exterior flanges 34 are generally parallel to the wall board 20.
Power is brought to the outlet box 18 via conductors 40 housed in a
conduit or cable 41 secured by an elbow connector 42 to the box. In
its mounted position, the outlet box 18 fits within a larger
opening 44 in the exterior wall board 20 with a gap 45 around the
outlet box 18. Those skilled in the art will appreciate that the
profile of the outlet box 18 is not limited to the rectangular
configuration described: the profile of the outlet box 18 can be
rectangular, round, square, or any other profile desirable for a
particular application.
[0020] The siding 12 typically includes separate elongated sheets
or boards 12a-f, as illustrated in FIG. 1, which extend
horizontally and are lapped over one another with the lower edge of
each board overlapping the upper edge of the board immediately
below it. This provides that water on the exterior face of the
siding 12 runs down the wall and does not pass the innerfitting
sheets or boards 12a-f into the wall 10.
[0021] The outlet box cover 16 can be formed as a single piece of
plastic so that it is continuous across all corners. The outlet box
cover 16 is designed to fit with an attaching flange 52 flush
against the wall board 20 and under the siding 12, and encloses and
covers the outlet box 18. This not only encloses the outlet box 18
and presents an attractive appearance, but also provides a flat
exterior face against which the flange of the fixture can be
secured. This establishes sound mechanical joints between the wall
10 and outlet box cover 16 and between the lighting fixture 14 and
outlet box cover 16. The exterior face of the outlet box cover 16
can be provided with woodgrain impressions and/or in various colors
for added beauty.
[0022] The outlet box cover 16 includes an outer wall 54 with an
outer opening 62, a barrier wall 70 with an inner opening 72, a
surrounding wall 50, and an attaching flange 52. The attaching
flange 52 and the outer wall 54 are formed integrally with the
surrounding wall 50 at its opposite ends, respectively, and each is
disposed transversely to the surrounding wall 50. The surrounding
wall 50 is continuous circumferentially, formed of two pairs of
opposed wall sections 56 and 58 respectively interconnected at
generally right-angled corners 59. Moreover, the attaching flange
52 extends radially outward from the surrounding wall 50 and is
peripherally continuous about the surrounding wall 50. In one
embodiment, the attaching flange 52 projects between one and two
inches away from the surrounding wall 50. The outer wall 54 has an
outer opening 62 formed therein which is designed to line up
generally with the front opening 35 of the underlying outlet box
18. The barrier wall 70 extends from the outer wall 54 and
surrounds the outer opening 62. The barrier wall 70 is
substantially normal to the outer wall 54. In one embodiment, the
height of the surrounding wall 50 and the barrier wall 70 are
substantially equal, so that the barrier wall 70 extends from the
outer wall 54 to the outlet box 18 when the front of the outlet box
18 is mounted flush with the wallboard 20. The barrier wall 70
provides an electrically isolated path for the wires passing
through the outlet box cover 16 between the outlet box 18 and the
electric light fixture 14. The barrier wall 70 also provides a
compression member, bracing between the electric light fixture 14
and the outlet box 18 when the bolts connecting the electric light
fixture 14 to the outlet box 18 are tightened down to secure the
electric light fixture 14.
[0023] In use, the attaching flange 52 butts against the exterior
face of the wall board 20 and nails 64 or the like used for
securing the attaching flange 52 directly against the wall board
20. In this secured position, the outer opening 62 in the outer
wall 54 lines up with the inner opening 72 of the barrier wall 70
and the front opening 35 of the outlet box 18. As secured in place,
the outlet box cover 16 encloses and virtually hides the outlet box
18.
[0024] In one use of this invention, the siding sheets 12b-e
overlap the attaching flange 52 and butt or almost butt against the
surrounding wall 50. This directs water along the exterior face of
the siding 12 past and over the exterior of the outlet box cover 16
to minimize water migration to behind the attaching flange 52.
Also, since the attaching flange 52 is flush against the wallboard
20, this juncture can be adequately sealed by caulking and/or
compression fit against the wallboard 20 to minimize leakage to the
interior of the outlet box cover 16.
[0025] The particular interior dimension across the hollow within
the surrounding wall 50 from the one wall section 56 to the
opposite wall section 58 is of the order of 4 to 7 inches, for
example. This allows for the outlet box cover 16 to be positioned
over most conventionally sized electric outlet boxes 18 while yet
providing clearance radially of the box to the surrounding wall 50.
In one embodiment, the outer opening 62 in the outer wall 54 is
rectangular in shape and is sized to correspond to the front
opening 35 provided in the underlying outlet box 18. In another
embodiment, the outer opening 62 in the outer wall 54 is round in
shape and is sized to correspond to the front opening 35 provided
in the underlying outlet box 18. The electric outlet box 18 can be
mounted so that its front opening 35 is flush with the exterior of
the wallboard 20, so that the barrier wall 70 butts or nearly butts
against the exterior flanges 34 of the outlet box 18. The front
opening 35 of the outlet box 18 and the inner opening 72 of the
outlet box cover 16 line up. The light fixture flange 14a can be
mounted directly flush against the outer wall 54 which in turn is
strengthened by contact with the underlying outlet box 18 through
the barrier wall 70. The lighting fixture 14 is secured to the
outlet box 18 after the leads from the fixture are electrically
connected by screw caps or the like to the conductors 40 in the
outlet box 18.
[0026] The outlet box cover 16 can be formed by injection molding.
It is possible to emboss the exterior face of the cover during
injection molding with woodgrained impressions. This can be used to
match the outlet box cover 16 with woodgrained siding. It is
further possible to precolor the outlet box cover 16 by tinting the
plastic before it is molded into the outlet box cover 16, allowing
matching with the siding color and/or the lighting fixture color.
For example, black might be a primary color of the outlet box cover
16 since many typical light fixtures 14 as illustrated are colored
in a gloss black enamel; but other colors would of course be
possible.
[0027] The plastic outlet box cover 16 forms an insulator enclosing
the electric outlet box 18, protecting against shocks that might
occur because of loose or defective wiring within the outlet box 18
and isolating sparks that can occur within the outlet box 18 and/or
the barrier wall 70. The plastic outlet box cover 16 is also
durable and does not scratch, dent or rust, and is maintenance free
in use. As noted, the color selection can match the color of siding
used, and further the woodgrain exterior can blend in with the
typical woodgrain texture of the siding. The outlet box cover 16
also weatherizes the wall structure against air and/or water
leakage as might be possible past the gap around the outlet box 18
and into the wall 10.
[0028] Those skilled in that art will appreciate that the outlet
box cover 16 can be used with any electrical or non-electrical
device that can be mounted to an electrical box. While a light
fixture 14 has been illustrated as secured against the outlet box
cover 16, it would be possible to install an electrical outlet (not
shown) in the outlet box cover 16. Such an electrical outlet could
be secured mechanically to the outlet box 18 by bolts passing
through the outlet box cover 16 to the exterior flanges 34, and a
closure plate could span and close the open outer opening 62 of the
outlet box cover 16. With proper seals between the closure plate
and the electrical outlet back and/or cover face 54, this butted
connection would preclude leakage into the interior space within
the outlet box cover 16. The electrical outlet receptacles could be
covered with a hinged plate to keep them clean when not being
used.
[0029] While the exemplary use of the outlet box cover 16 as
described above is use in connection with a sided exterior wall,
the outlet box cover 16 can be used to cover an electric outlet box
18 located in a wall that is not sided. Again, the outlet box cover
16 provides a durable watertight closure arrangement to minimize
leakage into the wall structure and to minimize electrical shorts,
any of which might be damaging and/or energy inefficient.
[0030] FIGS. 5-8, in which like elements share like reference
numbers with FIGS. 1-4, are back views of embodiments of outlet box
covers made in accordance with the present invention. The outlet
box covers are suited for various front openings shapes in the
outlet box. The views are looking from the attaching flange 52
toward the outer wall 54, i.e., from the outlet box toward the
outlet box cover. Those skilled in the art will appreciate that the
openings shapes described are exemplary and that other shapes can
be used as desired.
[0031] FIGS. 5 and 6 shows electrical box covers 16 for use with an
outlet box having a rectangular and a round front opening,
respectively. The barrier wall 70 is the shape of the front opening
of the outlet box so that the barrier wall 70 can butt against the
outlet box and continue the electrical isolation of the electrical
box through the electrical box cover 16.
[0032] FIG. 7 shows an electrical box cover 16 for use with an
outlet box having either a rectangular or a round front opening.
The barrier wall 70 includes a rectangular portion 74 and a round
portion 76. When the electrical box cover 16 is used with an outlet
box having a rectangular front opening, the rectangular portion 74
of the barrier wall 70 butts against the rectangular outlet box.
When the electrical box cover 16 is used with an outlet box having
a round front opening, the round portion 76 of the barrier wall 70
butts against the round outlet box. Thus, the electrical box cover
16 can be used for more than one shape of electrical box.
[0033] FIG. 8 shows an electrical box cover 16 having a removable
opening panel 78. The removable opening panel 78 continues the
plane of the outer wall 54 into the outer opening of the outer wall
54. The removable opening panel 78 can be trimmed out to a desired
shape or removed completely at the installation site. In one
embodiment, the removable opening panel 78 can be perforated with
one or more patterns to allow easy removal to a particular shape.
In another embodiment, the removable opening panel 78 can be the
same thickness and uniformity as the outer wall 54, and the
removable opening panel 78 can be cut to the desired opening with
scissors, side cutters, a utility knife, or the like. In yet
another embodiment, the removable opening panel 78 can form a
cutting aperture 80 which provides an opening in the removable
opening panel 78 to start the cut.
[0034] FIGS. 9-11, in which like elements share like reference
numbers with each other and with FIGS. 1-4, show various views of
an outlet box cover made in accordance with the present invention
with an trim ring. The trim ring encircles the surrounding wall of
the outlet box cover to provide an additional seal around the
siding.
[0035] The trim ring 114 includes a ring wall 115 and ring
extending flange 117 substantially normal to the ring wall 115. In
one embodiment, the trim ring 114 is one-piece, continuous, and
joint-free. The ring wall 115 closely engages the surrounding wall
50 of the outlet box cover 16 when the trim ring 114 is installed
on the outlet box cover 16. The ring wall 115 and the ring
extending flange 117 define a generally L-shaped channel 118 about
the ring wall 115 for receiving and concealing siding edges 113
which are located adjacent to the outlet box outer wall 54. The
ring extending flange 117 overlies the attaching flange 52. The
trim ring 114 avoids the need to caulk around the siding edges 113
and provides ornamental concealment of the siding edges 113.
Complementary ridges and grooves on the ring wall 115 and the
surrounding wall 50 can be used to retain the ring wall 115 on the
outlet box cover 16. The complementary ridges and grooves can
extend continuously, partially, or locally around the ring wall 115
and the surrounding wall 50. In one embodiment, a linear ridge is
provided on the surrounding wall 50 and one or more linear grooves
are provided in the ring wall 115. Parallel spacing of the linear
grooves allows the trim ring 114 to accommodate different
thicknesses of siding 12, with the linear ridge residing in the
linear groove appropriate to the thickness.
[0036] The trim ring 114 can be attached to the outlet box cover 16
before or after the siding 12 is installed. When the trim ring 114
is attached before the siding 12 is installed, the siding edges 113
can be slipped into the generally L-shaped channel 118 about the
ring wall 115. When the trim ring 114 is attached after the siding
12 is installed, the ring wall 115 can be slipped between the
siding edges 113 and the surrounding wall 50.
[0037] The trim ring 114 can be made of any suitable material, such
as metal, plastic, or any other material as desired for a
particular application. In one embodiment, the trim ring 114 is
molded of a lightweight durable plastic, such as polypropylene or
the like. In one embodiment, the trim ring 114 has a ring wall 115
and ring extending flange 117 of about 0.040 inches thickness, with
the ring wall 115 of about 3/4'' straight width which is the same
as the width of the surrounding wall 50, and with the ring
extending flange 117 of about 5/8'' width. Similarly, the trim ring
114 can be provided in various colors and finishes, such as wood
grain finishes, as desired.
[0038] Those skilled in the art will appreciate that the trim ring
is not limited to the exemplary L-shape cross section described
above and can have other cross sections as desired. In another
embodiment, the cross section can be U-shaped as described in U.S.
Pat. No. 5,133,165 to Wimberly, incorporated herein in its entirety
by reference. To form a U-shaped cross section, a second ring
extending flange can be added to the trim ring of FIGS. 9-11
substantially normal to the ring wall and on an end of the ring
wall opposite the first ring extending flange
[0039] FIG. 12, in which like elements share like reference numbers
with FIGS. 1-4 and 9-11, is a side view of a trim ring and an
outlet box cover made in accordance with the present invention. The
ring wall 115 and the surrounding wall 50 have complementary ridges
and grooves to retain the trim ring 114 on the outlet box cover 16.
In one embodiment, the ring wall 115 includes grooves 90 and the
surrounding wall 50 includes ridges 92. The ridges 92 fit into the
grooves 90 when the trim ring 114 is slid over the outlet box cover
16. The profile of the ridges 92 can be selected so that the ridges
92 spring the ring wall 115 away from the surrounding wall 50 until
the ridges 92 fit into the grooves 90, thus locking the ridges 92
into the grooves 90. In one embodiment, the ridges 92 increase in
height from the outer wall 54 toward the attaching flange 52 so
that the tapered profile of the ridge 92 eases the groove 90 over
the ridge 92 until the complementary ridge 92 and groove 90 lock in
place. In another embodiment, the grooves 90 associated with a
particular ridge 92 are spaced apart from each other so that the
distance between the ring extending flange 117 and the attaching
flange 52 are adapted for particular applications. For example, the
grooves 90 can be spaced apart so that the distance between the
ring extending flange 117 and the attaching flange 52 provides a
first distance to fit insulated siding when a first groove is
locked on the associated ridge and a second distance to fit
uninsulated siding when a second groove is locked on the associated
ridge. Those skilled in the art will appreciate that the grooves 90
associated with a particular ridge 92 can spaced apart from each
other as desired for a particular application. A number of grooves
can be associated with a particular ridge, with uniform or
non-uniform spacing between adjacent grooves.
[0040] While the embodiments of the invention disclosed herein are
presently considered to be preferred, various changes and
modifications can be made without departing from the scope of the
invention. Those skilled in the art will appreciate that the
embodiments described are exemplary and that alternative circuits
can be used as desired for particular applications. The scope of
the invention is indicated in the appended claims, and all changes
that come within the meaning and range of equivalents are intended
to be embraced therein.
* * * * *