U.S. patent application number 09/935093 was filed with the patent office on 2003-02-27 for electrical circuit tracing device.
Invention is credited to Klein, Raymond H., Luebke, Thomas M., Steber, George R., Wiesemann, David L..
Application Number | 20030038723 09/935093 |
Document ID | / |
Family ID | 25466583 |
Filed Date | 2003-02-27 |
United States Patent
Application |
20030038723 |
Kind Code |
A1 |
Luebke, Thomas M. ; et
al. |
February 27, 2003 |
ELECTRICAL CIRCUIT TRACING DEVICE
Abstract
An electrical circuit tracing device comprising a transmitter
that includes a pocket for storing the receiver is disclosed. The
transmitter further comprises a storage compartment for maintaining
a plurality of pre-wired connectors, and a clip which can be used
to attach the transmitter to a pocket, a belt, or another carrying
device.
Inventors: |
Luebke, Thomas M.;
(Menomonee Falls, WI) ; Wiesemann, David L.;
(Pewaukee, WI) ; Steber, George R.; (Mequon,
WI) ; Klein, Raymond H.; (Milwaukee, WI) |
Correspondence
Address: |
QUARLES & BRADY LLP
411 E. WISCONSIN AVENUE
SUITE 2040
MILWAUKEE
WI
53202-4497
US
|
Family ID: |
25466583 |
Appl. No.: |
09/935093 |
Filed: |
August 22, 2001 |
Current U.S.
Class: |
340/635 ;
324/690; 340/693.5 |
Current CPC
Class: |
G01R 1/06788 20130101;
G01R 1/04 20130101; G01R 31/58 20200101; G01R 31/54 20200101 |
Class at
Publication: |
340/635 ;
340/693.5; 324/690 |
International
Class: |
G08B 021/00 |
Claims
We claim:
1. An electrical circuit tracing device, the device comprising: a
transmitter including a transmitter circuit and a transmitter
housing, the transmitter housing defining a pocket; a connector
connected to said transmitter and connectable to a conductor to a
to be traced; and a receiver including a receiver circuit for
detecting a signal transmitted from said connector to said
conductor, wherein the pocket of the transmitter housing is
dimensioned to receive and store the receiver therein.
2. The electrical circuit tracing device as defined in claim 1,
wherein the pocket of the transmitter tapers such that a top
aperture is wider than a bottom of the pocket.
3. The electrical circuit tracing device as defined in claim 1,
wherein the receiver comprises a middle portion that is relatively
wider than a bottom portion, the middle portion providing a
frictional force between the internal walls of the pocket and the
receiver.
4. The electrical circuit tracing device as defined in claim 1,
wherein the pocket includes a ridge extending from a bottom
wall.
5. The electrical circuit tracing device as defined in claim 1,
wherein the transmitter further comprises a clip for coupling the
transmitter to a belt.
6. The electrical circuit tracing device as defined in claim 1,
wherein the transmitter further comprises a covered storage
compartment.
7. The electrical circuit tracing device as defined in claim 6,
wherein the covered storage compartment includes a hinged lid.
8. The electrical circuit tracing device as defined in claim 7,
wherein the covered storage compartment includes a plurality of
connectors pre-wired to a transmitter circuit.
9. The electrical testing device as defined in claim 1, further
comprising a connector storage rack.
10. The electrical circuit tracing device as defined in claim 5,
wherein the hinged lid further comprises a latching device for
latching the lid to the housing 16.
11. An electrical circuit tracing device, comprising: a transmitter
including a transmitter circuit and a transmitter housing
containing the transmitter circuit, the transmitter housing
including a storage compartment with a hinged lid, the storage
compartment including one or more connectors pre-wired for
connection to a circuit to be traced; and a receiver including a
receiver circuit for detecting a signal transmitted along the
circuit to be traced by the transmitter circuit.
12. The electrical circuit tracing device as defined in claim 11,
wherein at least one of the connectors is a coaxial cable
connector.
13. The electrical circuit tracing device as defined in claim 11,
wherein at least one of the connectors is a telephone jack.
14. The electrical circuit tracing device as defined in claim 11,
wherein at least one of the connectors is a straight blade.
15. The electrical circuit tracing device as defined in claim 11,
wherein at least one of the connectors is an alligator clip.
16. The electrical circuit tracing device as defined in claim 11,
wherein the storage compartment includes a storage rack for
selectively coupling the pre-wired connectors to the transmitter
housing.
17. The electrical circuit tracing device as defined in claim 11,
wherein the pre-wired connectors are electrically coupled to the
transmitter circuit.
18. The electrical circuit tracing device as defined in claim 11,
wherein the storage compartment includes a lid.
19. The electrical circuit tracing device as defined in claim 18,
wherein the lid is hinged to the transmitter housing.
20. The electrical circuit tracing device as defined in claim 11,
wherein the connectors are pre-wired to the transmitter
circuit.
21. An electrical circuit tracing device comprising: a transmitter,
the transmitter including a housing defining a pocket; a receiver,
wherein the pocket of the transmitter housing is dimensioned to
receive and store the receiver therein; and a clip coupled to the
transmitter housing.
22. The electrical circuit tracing device as defined in claim 21,
wherein the clip comprises a flexible material which can be pulled
back to provide a space for inserting a carrying device between the
clip and the housing of the transmitter.
23. The electrical circuit tracing device as defined in claim 21,
wherein the transmitter housing further comprises a storage
compartment for storing a connector for electrically coupling the
transmitter to a circuit to be traced.
24. A transmitter circuit for transmitting a signal on a conductor,
the transmitter circuit comprising: a power source comprising a
plurality of triple A batteries; an amplifier; and a
microcontroller, wherein the microcontroller is powered by the
power source, the microcontroller is programmed to modulate a
signal in the audio range, and the amplifier amplifies the signal
to a higher voltage value.
25. The transmitter circuit as defined in claim 24, wherein the
power source comprises three triple A batteries.
26. The transmitter circuit as defined in claim 24, wherein the
microcontroller includes a sleep mode.
27. The transmitter circuit as defined in claim 26, wherein the
sleep mode is activated by a timer.
28. The transmitter circuit as defined in claim 26, further
comprising a switch for toggling the microcontroller between the
sleep mode and an awake mode.
29. The transmitter circuit as defined in claim 26, wherein the
amplifier is a step-up transformer.
30. An electrical circuit tracing device comprising: a transmitter
having circuitry for producing an electrical signal which can be
coupled to a conductor and detected by receiver circuitry which is
capacitively coupled to said conductor; and a receiver containing
said receiver circuitry, said circuitry including a probe and an
output LED, said LED being positioned in said receiver adjacent to
said probe, and wherein said LED has one node connected to a power
supply and another node connected to a resistor which is connected
to the collector of a transistor which controls the flow of current
through said LED.
31. The electrical circuit tracing device of claim 30 wherein the
LED is connected to the power supply and to the resistor with a
shielded cable.
32. The electrical circuit tracing device of claim 31, wherein the
shielded cable is routed to avoid close proximity with said probe.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an apparatus for tracing of
electrical conductors where the path of the conductors to be traced
is not readily observable due to either surrounding structure or
the conductors' disposition among many conductors of similar
appearance. More particularly, this invention pertains to a tracing
apparatus which combines a number of features to simplify use of
the device.
BACKGROUND
[0002] In electrical installations, a number of electrical
conductors are frequently routed through structures which hide the
conductors from view. Examples are readily found in the average
home, where telephone, cable television, and electrical wiring is
generally located behind the wall, where it does not disrupt the
appearance of the home, and where interaction between the wiring
and the residents of the home is minimized. Similarly, in
industrial installations, electrical wiring is frequently bundled
and confined in an out of the way location, where accidental
intervention with the wiring cannot occur.
[0003] In such installations, individual conductors can, therefore,
be difficult to test, both because the tester cannot readily see
the conductor, and because a specific conductor is difficult to
isolate in a large number of conductors having a similar
appearance. In these situations, the route of a specific conductor
cannot be readily ascertained by visual tracing.
[0004] Because of the difficulty of tracing wires in walls or other
conduits, or in a large bundle of similar wires, line or wire
tracing devices have been developed. Wire tracing devices generally
comprise a transmitter for transmitting an electromagnetic signal
along a wire to be tested, and a receiver for wirelessly detecting
the signal at another location in the wire. The electromagnetic
signal is preferably a distinct modulated signal in the audio
range. The receiver acts as an antenna, receiving and supplying the
audio signal to provide an audio signal, the strength of which
varies depending on the distance of the receiver from the wire
carrying the audio can signal. Preferably, the receiver also
includes a light emitting diode, which is lit to indicate a
detected signal. Like the audio signal, the intensity of the light
preferably increases as the receiver approaches an active wire.
[0005] The transmitter device is preferably stationary, and is
electrically coupled directly to the wire to be tested. Typically,
the transmitter comprises a circuit powered by a relatively large
nine volt D cell battery, and the amplitude of signals produced by
the battery are limited to nine volts. Furthermore, the nine volt
power supply must supply a relatively large level of current to
provide sufficient signal for detection.
[0006] The receiver device is a moveable, hand-held device, which
can be moved along the outside of a wall or conduit to detect the
transmitted signal, thereby providing an indication both of where
the wire is routed and whether electrical continuity exists in the
wire.
[0007] Wire testing and tracing devices, therefore, generally
comprise a number of components. As noted above, the test unit
itself comprises both a transmitter device and a handheld receiver,
where the transmitter device must be relatively large to
accommodate the nine volt battery power source. To trace wires in,
for example, a home, a number of connectors are also required. For
example, in a home inspection, a tester may need to test telephone,
cable television, and AC voltage connectors. Although typical
connectors such as alligator clips can be used for such testing,
these devices generally require cutting and stripping of wires.
Therefore, testers generally require specific phone jack, coaxial
cable, and a straight blade AC electrical connectors which can be
connected directly to existing wires without the need for stripping
or cutting conductors. Furthermore, because the current levels
supplied by the nine volt battery are high, spare batteries are
often required. Because of the size of the components, as well as
the large number of both components and connectors required,
typical wire tracing devices, therefore, must be carried in a bag
or carrying case.
[0008] Carrying cases and bags, however, can be problematic for the
electrician or technician in the testing environment. The tracing
of wires, for example, is generally only the first step in an
electrical test. A technician or electrician therefore often
requires a number of additional testing devices including
voltmeters, current detecting devices, and other electrical testing
equipment. The need for a bag or carrying case for each individual
piece of equipment can cause significant inconvenience when all of
the equipment must be carried by a single user. Furthermore, when a
plurality of connectors and testing devices are maintained in a bag
or carrying case, required parts of the testing equipment are
frequently lost. Such equipment, for example, is frequently stored
in a pocket or with another piece of test equipment rather than
returned to the appropriate bag after testing. Such equipment is
also frequently "borrowed" for another application and not
returned. Furthermore, loose connectors and other equipment is
frequently left behind when the testing is completed.
[0009] There remains a need, therefore, for a wire tracing device
which simplifies the use and storage of wire tracing equipment.
SUMMARY OF THE INVENTION
[0010] The present invention is a wire tracing or electrical
circuit tracing device which provides a transmitter, receiver, and
a plurality of connectors in a single, compact, easy-to-use,
easy-to-transport package.
[0011] To decrease the size of the device, the transmitter circuit
is designed to operate on a low voltage supply, and can be operated
with small triple A batteries, as opposed to the nine volt battery
required in prior art devices. The transmitter is preferably
operated on a three volt supply, which is amplified by a step up
transformer to provide an operating voltage of approximately 20
volts, thereby providing a more robust signal than prior art
devices. A small, inexpensive microcontroller controls and
generates the signal, and also provides a sleep function, wherein
the transmitter is automatically turned off after a predetermined
operation time.
[0012] The transmitter circuitry of the wire tracing device is
enclosed in a multifunctional housing. The housing is formed to
include a pocket dimensioned to hold the receiver, thereby
providing a location for storing the individual parts of the wire
tracing device in a single package without the need for an external
case or bag. Furthermore, a clip is coupled to the back of the
housing in such a way that the transmitter can be snap fit onto a
belt or other carrying device in order to eliminate the need to
separately carry the wire tracer. The housing of the transmitter in
effect provides a "holster" for storing and transporting the wire
tracing device.
[0013] To further simplify the use of the device, the housing of
the transmitter section includes a storage rack designed to hold a
plurality of common electrical connectors. The connectors can, for
example, include a phone jack, a coaxial connector, and a male
straight blade connector, each of which can be snap fit into the
rack, where the connector is held in place during
transportation.
[0014] Each of the connectors is preferably electrically coupled to
the internal transmitter circuitry such that, when a test is
required, a user need only connect the appropriate connector to a
matching socket, and then activate the receiver to trace the line.
Because the connectors are pre-wired to the testing device, the
connectors cannot be lost or misplaced. Furthermore, the connectors
provide easy access to a number of common connections, without the
need for cutting or stripping wires.
[0015] Preferably, the storage rack and associated electrical
connectors are coupled to the storage compartment which can be
closed by shutting a lid. The lid is preferably hinged, and can
include one or more latching devices for holding the lid in a
closed position when the wire tracing device is not in use.
[0016] These and other objects and advantages of the invention will
be apparent from the detailed description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view of an electrical circuit tracer
constructed in accordance with the present invention;
[0018] FIG. 2 is an exploded view of the electrical circuit tracer
of FIG. 1, the exploded view showing the separate transmitter and
receiver components;
[0019] FIG. 3 is a rear plan view of the electrical circuit tracer
of FIG. 1;
[0020] FIG. 4 is a side exploded view of the electrical circuit
tracer of FIG. 1 showing a back lid of the device in an open
position;
[0021] FIG. 5 is a rear plan view of the transmitter showing the
back lid of FIG. 4 in the open position;
[0022] FIG. 6 is a fragmentary side sectional view of the
transmitter of the electrical circuit tracer of FIG. 1 showing an
internal pocket in which the receiver is positioned;
[0023] FIG. 7 is a rear plan view of the receiver of the electrical
circuit tracer of FIG. 1;
[0024] FIG. 8 is a circuit diagram of a transmitter circuit
constructed in accordance with the present invention;
[0025] FIG. 9 is a circuit diagram of a receiver circuit for use in
conjunction with the transmitter circuit of FIG. 8; and
[0026] FIG. 10 is an illustration of the electrical circuit tracing
device in use tracing an electrical circuit.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0027] Referring now to the Figures and more particularly to FIGS.
1 and 2, an electrical circuit tracing device constructed in
accordance with the present invention is shown at 10. The
electrical circuit tracing device 10 generally comprises two parts:
a transmitter 12 for transmitting a signal along a wire to be
tested, and a receiver 14 for detecting the signal from the
transmitter 12 and for providing an indication that a conductor is
carrying the transmitted signal. The transmitter 12 comprises a
housing 16 configured to include a pocket 18, wherein the pocket 18
is dimensioned to receive and store the receiver 14, as described
more fully below. A depression 26a and 26b is defined in each of
the opposing sides of the housing 16, the depressions 26a and 26b
allowing for a user to easily grip and carry the transmitter
12.
[0028] Referring still to FIGS. 1 and 2, the front panel 20 of the
housing 16 includes an ON/OFF switch 22, and an indicator light or
light emitting diode (LED) 24. Circuitry for providing the
transmission function (FIG. 8) is enclosed in the housing 16, and
is activated by the ON/OFF switch 22. When the ON/OFF switch 22 is
placed in the ON position, the LED 24 is lit to indicate that the
electrical wire tracer is active. Although a specific circuit for
providing the transmission function is shown and described below, a
number of different transmitter and receiver pairs can be
advantageously employed in conjunction with the disclosed housing,
storage, and other concepts.
[0029] Referring now to FIG. 3, a back view of the transmitter 12
is shown. The back of the transmitter 12 includes a clip 28 which
is coupled to the housing 16. The clip 28 comprises a flexible
material, such as plastic, rubber, certain types of metals, or
other materials such that the clip 28 can be pulled away from the
housing 16 and positioned on the opposing side of a carrying device
from the housing 16. The carrying device can be, for example, a
pocket, belt, the edge of a carrying case, or any of a number of
different mounting materials to which it is convenient to
temporarily couple the electrical wire tracing device. Once the
clip 26 is positioned over the material, the clip 26 is allowed to
flex closed against the housing 16 such that the carrying device is
held between the clip and the housing 16. The clip 26 can be
coupled to the housing 16 with a coupling device 32 such as a
threaded screw, a rivet, or any of a number of other devices known
to those of skill in the art.
[0030] Referring now to FIGS. 3 and 4, the back of the transmitter
12 preferably also includes a lid 30 which is mounted to the
housing 16 with a hinge 34, such that the lid 30 can be selectively
open and shut to reveal a storage compartment 35. In the closed
position, (FIG. 3), the lower edge 36 of the lid 30 is locked in
place by means of a light snap fit with one or more locking catches
38. The lower edge 36 also preferably defines a semi-circular
finger hole 40 which can be accessed by the user to apply a force
to the lid 30 to release the lid 30 from the locking catches
38.
[0031] Referring now to FIGS. 4 and 5, when the lid 30 is in the
open position, a plurality of connectors and associated leads 54a-d
in the storage compartment 35 are accessible to a user. The
connectors can include, as shown, an alligator clip 42, telephone
jack 44, coaxial connector 46, and a straight blade 48. Each of
these connectors 42, 44, 46, and 48 are coupled to a lead 54 which
is, in turn, electrically coupled to the transmitter circuit housed
between the housing 16 and a base plate 50 of the storage
compartment 35. A plurality of apertures 52a-d are defined in the
base plate 50 through which the leads 54 can be routed to
connection points on the transmitter circuit (FIG. 8). The base
plate 50 also includes a storage rack 56 for receiving the leads 54
and associated connectors 42, 44, 46, and 48. Preferably, the
storage rack 56 is sized and dimensioned to allow the selected
connectors and leads 54 to be snap fit in place, thereby
simplifying closure of the lid 30 and transportation of the
electrical circuit testing device. As shown, the storage rack 56
comprises a plurality of vertical dividers 55 which divide the
storage compartment 35 into four separate compartments 59, 61, 63,
and 65 for storing each connector 42, 44, 46, and 48 and the
associated leads 54a-d. The vertical dividers 55 extend in a
substantially perpendicular direction upward from the base 35. In
the compartments 61, 63, and 65, the vertical dividers 55 are
coupled to a plurality of horizontal or generally horizontal cross
bars 57. The cross bars 57 extend from each side of the vertical
dividers 55 into the adjacent compartment a distance less than one
half the distance across the compartment, thereby leaving a space
between the horizontal cross bars 57 coupled to adjacent vertical
dividers 55 in which the leads 54a through 54d can be snap fit. The
compartment 59 includes one or more cylindrical pegs 67 extending
in a direction substantially perpendicular to the base, the pegs
providing a means for winding the lead 54a into the compartment,
and for snap fitting the lead 54a in place.
[0032] Each of the connectors 42, 44, 46, and 48 is pre-wired to
allow transmission of an electrical signal from the transmitter
circuit, through the lead 54 to the connector 42, 44, 46, and 48.
The telephone jack connector 44 is wired to be coupled directly to
an associated female telephone jack socket, and to transmit a
signal directly along the telephone wiring to trace the associated
circuit. Similarly, the coaxial cable connector 46 is wired to be
coupled directly to a coaxial cable socket, and the straight blade
connector 48 to be coupled to either side of an electrical power
socket. Therefore, connectors for a number of frequently-probed
circuits are readily available to a user. The alligator clip 42
allows for probing of any other wire or connector coupled to a
circuit requiring tracing.
[0033] Referring now to FIG. 6, the pocket 18 is shown as sized and
dimensioned to receive the receiver 14. The pocket 18 includes
internal side walls 68 and 70 which are tapered inward, such that
the pocket is widest at the top aperture 76 and narrows as it
approaches the bottom wall 72 of the pocket. The bottom wall 72
includes a ridge 74, extending into the pocket 18 from the corner
formed by the bottom wall 72 and side wall 70.
[0034] Referring again to FIG. 2, the receiver 14 comprises a
receiver circuit (FIG. 9) housed in an elongated housing 58. A
distal end of the housing 58 comprises a sensor tip 60 which is to
be directed at a wire to detect a signal transmitted from the
transmitter 12, as shown in FIG. 10. Referring still FIG. 2, the
housing 58 of the receiver 14 further comprises a speaker 66 which
provides an audio signal generated by an internal circuit (FIG. 9)
when a transmitted signal is detected. Referring now to FIG. 7, the
receiver 14 further comprises an ON/OFF switch 62 and an indicator
light 64 that provides a visual indication when a signal has been
detected. A thumbwheel 65 establishes the maximum strength of the
output signal provided by the speaker 66 and the indicator light
64.
[0035] Referring still to FIG. 2, the housing 58 of the receiver 14
is designed in a pen-shaped configuration which allows for easy
handling by a user when tracing a wire. The circumference of the
housing 58 is varied such that the circumference of a middle
portion 80 is wider than that of a top portion 82 and bottom
portion 84. A portion, for example the front 59 and back 61, of the
receiver 14 is rubberized to provide a good grip for the user, and
also to retain the receiver 14 in the pocket 18, as discussed
below.
[0036] Referring now to FIGS. 2, 4 and 6, as noted above, the
pocket 18 and receiver 14 are sized and dimensioned to allow
selective placement of the receiver 14 in the pocket 18 of the
transmitter 12 for storage. Also as noted above, the pocket 18 is
widest at the top 76, and narrows as it approaches a bottom wall
72. The relatively narrow bottom portion 84 of the receiver 14 can
therefore be slid through the pocket 18 until it contacts the ridge
74 extending from the bottom wall 72 of the pocket 18. As the
receiver 14 is inserted into the pocket 18, the wider middle
portion 80 of the receiver 14 is friction fit against the narrowing
inner walls 68 and 70. To provide a stronger frictional force, the
rubberized front 59 and back 61 deform to provide a frictional
surface to help hold the receiver 14 in the pocket 18. The
frictional fit of the wider middle portion 80 of the receiver 14 in
the pocket 18 combines with a force imposed on the receiver by the
ridge 74 to hold the receiver 14 in position in the pocket 18, even
when the transmitter 12 and receiver 14 are subjected to forces
which tend to separate them. For example, the receiver can be held
in place even when the combined transmitter 12 and receiver 14 is
turned sideways or upside down.
[0037] Referring now to FIG. 8, the transmitter circuit in the
transmitter 12 provides three basic functions: modulating a signal
for transmission in the audio range of frequencies, amplifying the
voltage of the transmission signal, and providing the transmission
signal to the connectors 42, 44, 46, and 48 described above. To
provide these functions, the major components of the transmitter
circuit include a voltage source 82, a step-up transformer 84, and
a microcontroller 86.
[0038] The microcontroller 86 is a low voltage component, requiring
only a three volt DC power supply for operation. The voltage source
82 can therefore be small, and is preferably provided by two triple
A batteries. Software stored in the microcontroller 86 provides a
modulated output signal in the audio range. The output signal is
applied to the input of the step-up transformer 84 at points 81 and
83 to increase the magnitude of the signal for transmission. The
microcontroller 86 also provides a timing function, which causes
the electrical circuit tracing device 10 to enter a "sleep" mode
after a predetermined operation time of, for example, thirty
minutes. In the "sleep" mode, the transmitter circuit draws very
little current, and therefore the life of the batteries supplying
the voltage source 82 is extended significantly. Activation of the
momentary switch 22 re-activates the microcontroller 86 and ends
the "sleep" mode, and thereby provides a function of toggling the
microcontroller 86 between a "sleep" and an "awake" mode.
[0039] The step up transformer 86 receives the modulated input
voltage from the voltage source 82 between points 81 and 83 and
steps the voltage up such that the output voltage between pins 85
and 87 is about twenty volts for a three volt input signal. The
output is limited by zener diodes 91 and 93, and filtered by
capacitor 89. The modulated output signal is electrically coupled
to each of the connectors 42, 44, 46, and 48 through an RC filter
circuit 92a, 92b, 92c, and 92d respectively for transmission along
a wire being traced.
[0040] Referring now to FIG. 9, the receiver circuit of the
receiver 14 is activated by the switch 62 which applies a voltage
from power source 97 to the circuit. The power source 97 preferably
comprises a plurality of button cells providing a total of 6 volts
which provide sufficient power in a small, easy-to-handle
space.
[0041] The activated receiver circuit detects the transmitted
signal, and provides both an audio and visual output signal, the
strength of which are scaled to be indicative of the strength of
the detected transmission signal. The transmitted signal is
detected by the receiver at the probe 94, located in the sensor tip
60 of the receiver 14 as discussed above. The detected signal is
amplified by transistor 96, the maximum and minimum output of which
are controlled by the user though the potentiometer 97 activated by
the thumbwheel 65 described above. The output of the transistor 96
is presented to the audio power amplifier 98, which amplifies the
signal. The amplified signal is electrically coupled to the speaker
99 via capacitor 100, such that the speaker 99 provides an audio
output signal having a signal strength indicative of the strength
of the transmitted signal.
[0042] The amplified signal also enables transistor 104 via
resistor 102. The transistor 104 operates in conjunction with
resistor 106, capacitor 108 and LED 110 to provide a visual output
signal that varies with the strength of the detected signal. The
relative positions of the resistor 106 and diode 110, which are
reversed in most similar applications, are important in the
receiver configuration shown to prevent positive feedback from
affecting operation of the LED 110. Positive feedback can result,
for example, when there is a large voltage signal on the wires or
cable to LED 110. In this case, if the positions of resistor 106
and LED 110 are reversed there can be a voltage signal as large as
6 volts AC on the LED 110 wire. Since LED 110 is so close
physically to the probe 94, the probe could detect the LED 110
signal, which would be undesirable. However with the LED 110
connected as shown, the signal on the LED 110 is only about 1 volt
AC; a significant reduction which allows the placement of the LED
110 near the probe, as desirable when using the receiver 14.
Potential feedback problems are further reduced by connecting the
LED 110 to the circuit with a shielded cable 111. The shielded
cable is routed in the receiver 14 such that the cable 111 is not
in close proximity with the probe 94.
[0043] Referring now to FIG. 10, the electrical circuit tracer 10
is shown as used to trace an electrical circuit. The transmitter 12
is electrically coupled to a wire 80 that extends on two sides of
an obstruction 82 with the alligator clip 42. The transmitter 12
transmits an electromagnetic signal along the wire 80. The sensor
tip 60 of the receiver 14 is directed at the wire 80, in order to
detect the transmitted signal. No electrical contact between the
tip 60 and the conductor 80 is necessary since detection is
accomplished by capacitive coupling. When the transmitted
electromagnetic signal is detected by the receiver 14, the
indicator light 64 is lit and an audio signal is emitted from the
speaker 66. Although the receiver 14 is shown in close proximity to
the wire 80 and on the same side of the obstruction 82 as the wire
80 for clarity, the receiver 14 can detect the electromagnetic
signal through common obstructions such as a wood or plaster wall.
The electrical circuit tracer 10 is often used to trace a wire that
cannot be seen by the user.
[0044] It should be understood that the methods and apparatuses
described above are only exemplary and do not limit the scope of
the invention, and that various modifications could be made by
those skilled in the art that would fall within the scope of the
invention. For example, although a number of distinctive features,
including a covered storage compartment, pre-wired attached leads,
a pocket for storing the receiver, and a clip for attaching the
device to a selected carrying device have been described as a
single embodiment, each of these features can be provided
separately or in various combinations to provide a novel electrical
circuit tracer.
[0045] Additionally, although a specific shape has been shown for
each of the transmitter and receiver component parts, it will be
apparent that variations can be made to these configurations within
the scope of the invention. Various known types of lids, locking
devices, and hinges can be employed to provide a storage
compartment. Furthermore. various types of coupling means and other
devices can be used to maintain the receiver in the pocket of the
transmitter. Additionally, the pocket and storage compartment could
be formed in a housing of the receiver portion of the electrical
circuit testing device, as well as the transmitter side.
[0046] Also, different connectors can be pre-wired to the leads of
the storage compartment depending on the expected application of
the device. Furthermore, the storage compartment and/or associated
storage rack could be used to store loose wires and associated
connectors, and the transmitter could include associated plugs or
sockets for coupling loose wires to the transmitter circuitry.
Other such modifications will be apparent to those of ordinary
skill in the art. To apprise the public of the scope of this
invention, the following claims are made:
* * * * *