Abstract:
A circuit tester for testing operation of an electrical receptacle includes a speaker that generates an audible signal when a voltage is present at the electrical receptacle. A cap on the end of the circuit tester includes openings on the side through which the audible signal may pass. The cap may be rotated on/off the housing such that the openings on the side of the cap move along the side of the circuit tester and become partly or fully obstructed by the side of the circuit tester, thereby varying the volume of the audible signal.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to a test device for electrical circuits and, more particularly, to a circuit tester providing an audible indication that voltage is present at an outlet and which includes a variable volume feature. 
     When installing or maintaining the electrical service in a building, it is sometimes necessary to test operation of an outlet or to identify which circuit breaker supplies voltage to an outlet. Although the sequence of steps is different for each operation, the general principle is the same. When testing operation of the outlet, a circuit breaker is initially in the off position such that no voltage is provided to the outlet. A test device is inserted into the outlet and the circuit breaker is turned on. The test device provides an indication of voltage being present at the outlet. When identifying which circuit breaker supplies voltage to an outlet, the circuit breaker is initially in the on position such that voltage is provided to the outlet. The test device is inserted into the outlet and provides an indication that voltage is present at the outlet. Individual circuit breakers are turned off and the test device is monitored after each circuit breaker is turned off until it no longer provides the indication that voltage is present at the outlet. 
     In either instance, the outlet may be located some distance from the load center in which the circuit breakers are located. In residential construction, for example, the load center is typically located in a basement. The outlet to be tested may be located one or two stories above and/or across the house from the load center. Historically, it has been known to provide an audible alert to indicate that voltage is present at the outlet. However, if the outlet is located two stories above and across the house from the load center, the audible alert must be very loud to allow the person testing the outlet to hear the alert at the load center. Otherwise, the tester has to repeatedly travel between the load center and the outlet to determine whether the outlet is operating properly or to identify if the correct circuit breaker has been identified. This level of volume required to hear the alert between two stories and across a large residence may be undesirable when testing outlets in closer proximity to the load center, such as in a finished basement. Thus, it would be desirable to provide a circuit tester configured to provide an audible alert for which the volume may be controlled to a desired level. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a circuit tester for testing operation of an electrical receptacle. The electrical receptacle includes a hot socket electrically connected to a hot lead of an electrical service and a neutral socket electrically connected to a neutral lead of the electrical service. The circuit tester includes a speaker or other sonic device that generates an audible signal when a voltage is present at the electrical receptacle. The volume of the audible signal is loud enough that the circuit tester may be plugged into a receptacle at one location in a building and an operator can turn on/off circuit breakers in a service panel located another location within the building and listen for the audible signal to determine which breaker supplies power to the receptacle. A cap on the end of the circuit tester includes apertures on the side through which the audible signal may pass. The cap may be rotated on/off the housing such that the apertures on the side of the cap move along the side of the circuit tester and become partly or fully obstructed by the side of the circuit tester, thereby varying the volume of the audible signal. 
     According to one embodiment of the invention, a circuit tester tests operation of an electrical receptacle. The circuit tester includes a housing having an opening extending through an end of the housing and a set of prongs extending from the housing and configured to be inserted into the electrical receptacle. The set of prongs includes at least a first prong configured to engage the hot socket of the receptacle and a second prong configured to engage the neutral socket of the receptacle. An audible signal generator is mounted within the housing proximate to the opening in the end of the housing and is configured to emit an audible signal through the opening in the end of the housing when a voltage potential is present across the first prong and the second prong. A volume modulator is operatively connected with the end of the housing. The volume modulator includes an end having a closed area at least as large as the opening in the end of the housing and aligned with the opening. At least one side surface extends from the end of the volume modulator and operatively engages the housing to translate an inner periphery of the side surface with respect to an outer surface of the housing, varying the distance between the closed area of the volume modulator and the opening in the end of the housing between an open position, a closed position, and at least one intermediate position. A plurality of apertures extends through the side surface. At least a portion of each of the plurality of apertures is positioned beyond the end of the housing when the volume modulator is in the open position and the intermediate position, and each of the apertures is positioned along the outer surface of the housing in the closed position. 
     According to another aspect of the invention, the volume modulator operatively engages the housing such that the distance between the closed area of the volume modulator and the opening in the end of the housing is continuously varied between the open position and the closed position. Cross-sections of the end of the housing and of the volume modulator may be generally circular. A portion of the outer surface of the housing proximate to the end of the housing may be threaded, and a portion of the inner periphery of the volume modulator may be threaded complementary to the housing to operatively engage the housing. The threaded portion may be configured such that a plurality of rotations of the volume modulator translates the volume modulator between the open and closed positions. 
     According to another embodiment of the invention, a circuit tester for testing operation of an electrical receptacle includes a housing having a first end, a second end, and a generally cylindrical outer wall extending between the first end and the second end. A portion of the outer wall proximate to the second end is threaded. A plurality of prongs extends from the first end and is configured to be inserted into the electrical receptacle. An audible signal generator oriented within the housing emits an audible signal from the second end of the housing when a voltage is present between a first prong and a second prong selected from the plurality of prongs. A volume modulator includes a generally closed first end, a generally open second end, a cylindrical outer wall extending between the first and second ends, and a plurality of apertures extending through the outer wall proximate to the first end of the volume modulator. A portion of the inner periphery of the outer wall proximate to the second end is threaded complementary to the threaded portion of the outer wall of the housing, and the volume modulator may be rotatable between a first position and a second position with respect to the housing. In the first position, the plurality of apertures is located beyond the second end of the housing, and in the second position, the plurality of apertures is located between the first and the second ends of the housing. 
     According to another embodiment of the invention, a circuit tester for detecting the presence of voltage in an electrical receptacle includes a housing, a set of prongs extending from the housing, a means for generating an audible signal indicating the presence of voltage at the set of prongs, and a means for varying or modulating the volume of the audible signal. 
     Various other features, objects and advantages of the present invention will be made apparent from the following detailed description of the drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various exemplary embodiments of the subject matter disclosed herein are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout, and in which: 
         FIG. 1  is a perspective view of a circuit tester according to one embodiment of the invention in which the volume modulator is fully open; 
         FIG. 2  is a perspective view of the circuit tester of  FIG. 1  in which the volume modulator is fully closed; 
         FIG. 3  is a side elevation view of the circuit tester of  FIG. 1  in which the volume modulator is fully open; 
         FIG. 4  is a side elevation view of the circuit tester of  FIG. 1  in which the volume modulator is partially open; 
         FIG. 5  is a side elevation view of the circuit tester of  FIG. 1  in which the volume modulator is fully closed; and 
         FIG. 6  is a cross-sectional view of the circuit tester of  FIG. 1  taken at line  6 - 6  of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The various features and advantageous details of the subject matter disclosed herein are explained more fully with reference to the non-limiting embodiments described in detail in the following description. 
     Referring to  FIGS. 1-5 , a circuit tester  10  in accordance with the present invention includes a housing  12  having a first end  14 , a second end  16 , and a generally cylindrical outer wall  15  extending between the two ends. An opening  18  extends through the first end  14  of the housing  12 , and a set of prongs  20  extends from the second end  16  of the housing  12 . The set of prongs  20  is configured to be inserted into an electrical receptacle, or outlet, to test operation of the electrical receptacle. According to the illustrated embodiment, the set of prongs  20  includes a first prong  22 , a second prong  24  and a third prong  26 . The first prong  22  is be configured to engage a first socket in the electrical receptacle that is connected to a hot conductor. The second prong  24  is be configured to engage a second socket in the electrical receptacle that is connected to a neutral conductor. The third prong  26  is be configured to engage a third socket in the electrical receptacle that is connected to a ground conductor. Optionally, the set of prongs  20  may include only the first prong  22  and the second prong  24 . It is further contemplated that numerous other configurations may exist for the set of prongs  20  according to the electrical distribution system to which the electrical receptacle is configured to be connected. 
     The circuit tester  10  includes one or more windows  30  through which a visual indicator may be observed. Referring also to  FIG. 6 , the visual indicator may be a light-emitting diode (LED)  65 . As illustrated, the circuit tester  10  includes three windows  30  each aligned with a corresponding visual indicator. The visual indicators may be used to provide an indication to the user whether the circuit is wired correctly or incorrectly. For example, enabling various combinations of the visual indicators may indicate that one of the conductors is not connected, a pair of conductors has been interchanged, or the electrical receptacle is properly wired. 
     In addition to visual indicators, the circuit tester  10  includes an audible signal generator  55  contained within the housing  12 . According to the embodiment illustrated in  FIG. 6 , the audible signal generator  55  is a piezoelectric speaker having a first end  51  and a second end  53 . The audible signal generator  55  is configured to emit an audible signal from a recessed portion  57  in the first end  51 . The recessed portion  57  is aligned proximate to the opening  18  in the first end  14  of the housing  12  such that the audible signal is emitted therethrough. The audible signal generator  55  is electrically connected to a circuit board  60  via pins  52  extending from the second end  53  proximate to the circuit board  60 . Other electrical components, such as a capacitor  70 , are mounted to the circuit board  60  as required to energize the audible signal generator  55  when voltage is present between the first and second prongs,  22  and  24  respectively. A switch  50  is included in the circuit to selectively enable/disable the audible signal generator  55  if, for example, the user wishes to observe the visual indicators without receiving an audible signal. It is understood that any other suitable audible signal generators or sonic devices such as buzzers or other magnetic or electronic speakers may be used without deviating from the scope of the invention. 
     The circuit tester  10  also includes a volume modulator  40  operatively connected to the first end  14  of the housing  12  to vary the volume of the audible signal emitted from the audible signal generator  55 . The volume modulator  40  includes a first end  42 , a second end  44 , and a generally cylindrical outer wall  43  extending between the two ends. According to the illustrated embodiment, the first end  42  includes a generally planar surface having an outer periphery defined by the outer wall  43 . The second end  44  is generally open and configured to receive the first end  14  of the housing  12 . A portion  48  of the inner surface proximate to the second end  44  of the volume modulator  40  is threaded, and a portion  17  of the outer wall  15  of the housing  12  is also threaded complementary to the threaded portion  48  of the volume modulator  40 . Consequently, the volume modulator  40  rotatably engages the housing  12  of the circuit tester  10 . 
     A plurality of apertures  45  are spaced around the periphery of the outer wall  43  of the volume modulator  40 . The apertures  45  are generally elongated and have a first end  47  and a second end  49 . The apertures  45  extend orthogonal to the second end  49  along a portion of the outer wall  43  with the first end  47  proximate to the first end  42  of the volume modulator  40  and a second end  49  in a central portion of the cylindrical outer wall  43 . Optionally, the apertures  45  may have numerous other shapes and orientations without deviating from the scope of the invention. 
     With reference to  FIGS. 3-5 , the volume modulator  40  is movable between an open position and a closed position. As the volume modulator  40  is rotated with respect to the housing  12 , the complementary threaded portions,  48  and  17  respectively, engage to draw the volume modulator  40  either on to, or off of, the housing  12 . In  FIG. 3 , the volume modulator  40  is illustrated in a fully open position. The second end  49  of each of the apertures  45  is generally aligned with the first end  14  of the housing  12 , thereby maximizing the volume of the apertures  45  through which the audible signal may travel and, consequently, maximizing the volume of the audible signal emitted from the circuit tester  10 . As the volume modulator  40  is rotated in a first direction, it is drawn from the open position to an intermediate position, as shown in  FIG. 4 . The second end  49  of each aperture  45  is translated along the outer wall  15  of the housing  12  such that a portion of each aperture  45  is obstructed by the outer wall  15  of the housing  12  and a portion of each aperture  45  remains unobstructed such that the audible signal is emitted therethrough. As the volume modulator  40  is rotated further in the first direction, it is drawn from the intermediate position to a closed position, as shown in  FIG. 5 . The first end  47  of each aperture is now generally aligned with or translated beyond the first end  14  of the housing  12  such that the entire aperture  45  is obstructed by the outer wall  15  of the housing  12 . As a result, the audible signal must be transmitted through a solid material, such as the first end  42  of the volume modulator  40 , rather than air, thereby minimizing the volume of the audible signal emitted from the circuit tester  10 . When the volume modulator  40  is rotated in a second direction, opposite the first direction, the steps are reversed and the volume modulator  40  is moved from the closed position to the open position. Because the volume modulator  40  engages the housing  12  via the respective threaded portions,  48  and  17 , the volume is continuously adjustable between the maximum volume and the minimum volume. Preferably, the fit between the modulator  40  and the housing  12  is configured such that the friction between the two threaded portions,  48  and  17  respectively, is sufficient to resist motion independent of a user. Thus, the threaded engagement of the volume modulator  40  with the housing  12  provides numerous intermediate positions over which a wide range and fine control of the volume may be achieved. 
     It should be understood that the invention is not limited in its application to the details of construction and arrangements of the components set forth herein. The invention is capable of other embodiments and of being practiced or carried out in various ways. Variations and modifications of the foregoing are within the scope of the present invention. It also being understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention