Abstract:
A cable continuity tester and tracer includes a cylindrical barrel housing a battery, a cable connector with two contacts, a bicolor LED and a detachable, tone-generating portion. A circuit board in continuity with the battery, LED and both contacts of the connector permits the LED to glow read upon encountering a short in a tested cable, and to glow green upon encountering a low-resistance terminator on the cable of from 50 to 75 ohms. The tone generating portion issues an audible signal when placed on an opposite end of a cable from the tester, when the cable has good continuity.

Description:
This application claims the benefit of U.S. provisional application No. 60/108,304, filed Nov. 13, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to devices for testing and tracing electrical circuits; and, it relates more specifically to devices for identifying and continuity-testing cables and cable networks. 
     2. Description of the Related Art 
     Coaxial cables and cable systems are essential to the function of telephone systems; cable television (CATV) systems; security systems; closed-circuit television (CCTV) systems; local and wide area computer networks (LANs and WANs); and, other multi-node, and multi-user systems. Tracing individual cables through such systems, and confirming their electrical continuity, often causes significant problems. Cables are often not identified with corresponding tags, labels or color-coding at both ends, so technicians installing or testing pre-wire systems, or removing, repairing or re-routing the cables of an existing system, have to sort through and test each cable individually. This commonly entails sorting through a number of upstream cable ends at a junction box or panel, and testing each against individual downstream termini where they connect to separate televisions, workstations, security sensors, or the like. 
     In tracing a coaxial cable from its downstream terminus back to the junction box, a technician normally secures a short circuit or low-resistance cable terminator to the downstream terminus of the desired cable and then, back at the junction box, connects a volt-ohm meter (VOM) to each upstream cable end, one-by-one. All cables but the correct one will produce a substantially infinite resistance reading, while the desired cable will show continuity. If the standard a 75-ohm terminator is used at the downstream terminus, a 75-ohm resistance reading on the meter confirms that no mid-cable short is present. Proceeding one-by-one through a great number of cable ends is a very tedious, laborious process. And, it is even more difficult and time-consuming if the technician desires to determine which of a multitude of downstream termini is associated with a particular upstream end at the junction box. In that case, the technician must either affix a terminator to the upstream end and walk room-to-room or workstation-to-workstation connecting a VOM to each downstream terminus, searching for continuity. Or, the technician must connect the VOM to the upstream end of the desired cable at the junction box and, repeatedly, walk to a downstream terminus; connect a terminator; and, walk back to the junction box to read the meter. 
     Various devices have been used and proposed for more convenient testing and tracing in coaxial cable systems. Miniaturized, limited-purpose versions of VOMs having cables, probes, clips, adaptors, LED&#39;s, tone generators and streamlined cases are commonly available, but they are generally difficult to use among tangled masses of cable ends, and more often suited to toolbox rather than pocket transport. Even the smaller, simpler versions have significant drawbacks. For example, U.S. Pat. No. 4,864,225 issued to Long, et al. shows a cylindrical, battery-operated cable tester with a cable coupling on one end for axial, threaded engagement with a cable end, further including a continuity-indicating LED at the end opposite the cable coupling. A conventional cable terminator, for placement on a tested cable&#39;s opposite end, stores removably on the device&#39;s cable coupling. Although the Long, et al. device may be more convenient than meter reading, it would still have drawbacks in that it would be difficult to fit into tight places and to engage its threaded, axial coupling to cable ends. Furthermore, the device&#39;s LED is poorly positioned; it is set in a recess at the farthest point possible from the coupling end, which would make it least useful in checking for continuity during the process of engaging the coupling. 
     Accordingly, it appears there exists a need for an easily manipulable, easy to read device for testing and tracing cables in coaxial cable systems. 
     SUMMARY OF THE INVENTION 
     The cable continuity tester and tracer of the present invention is adapted to overcome the above-noted shortcomings and to fulfill the stated needs. It comprises: a body portion having proximal and distal ends; a portable power supply within the body portion; a connector at the body portion&#39;s proximal end having first and second contacts; means closely adjacent to the connector for visibly confirming continuity in a circuit; means for establishing a circuit from the first contact, to the power supply, to the visible circuit continuity-confirming means, through the body portion, and to the second contact; means selectively storable in secure engagement with the body portion for audibly confirming continuity in a circuit. 
     It is an object of the present invention to provide a cable circuit tester and tracer which has a built-in power source, and fits as easily in a shirt pocket as a pen. 
     It is a further object of the present invention to provide a cable circuit tester which includes a visible continuity indicator placed closely adjacent to the connector to which the cable under test is being coupled. 
     Yet another object of this invention is to provide a cable circuit tester which is both sized and configured to work in tight spaces. 
     Yet a further object of the present invention is to provide a cable continuity tester and tracer having a detachable toner unit able to be either press-engaged or threaded into a cable coupling. 
     Yet a further object of the invention is to provide a cable continuity tester and tracer with circuitry able to discern whether a line is shorted, or fitted with a low-resistance terminator cap. 
     Still a further object of the present invention is to provide a continuity tester and tracer able to detect both 50 ohm and 75 ohm terminator caps on tested cable lines. 
     Another object of the present invention is to provide a cable continuity testing and tracing kit, including adaptors for testing telephone lines, computer network lines and other types of cables and cable systems. 
     Still further objects of the inventive device disclosed herein will be apparent from the drawings and following detailed description thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the cable continuity testing and tracing device of the invention. 
     FIG. 2 is cross-sectional view of the device of FIG. 1, taken on line  2 — 2  of FIG.  1 . 
     FIG. 3 is an exploded version of the cross-sectional view of FIG.  2 . 
     FIG. 4 is a schematic diagram of the electrical circuit on the device&#39;s printed circuit board. 
     FIG. 5 is a table listing the vendors and model numbers of the components of the printed circuit board. 
     FIG. 6 is an exploded perspective view of the device of the invention in use. 
     FIG. 7 is a perspective view of the device of the invention in use in testing a cable between a junction box and a television in a room in a dwelling structure. 
     FIG. 8 is a perspective view of an adaptor for mating the device of the invention with an RJ 11  telephone connection. 
     FIG. 9 is side elevation view of the RJ 11  adaptor of FIG. 8 
     FIG. 10 is a perspective view of an adaptor for mating the device of the invention with a dual-contact USOC telephone connection. 
     FIG. 11 is a side elevation view of the dual-contact USOC telephone adaptor of FIG.  10 . 
     FIG. 12 is a perspective view of an adaptor for mating dual alligator clip leads with the device of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now specifically to the drawings, FIGS. 1 through 3 show the inventive cable continuity testing and tracing device, which is generally identified herein with the reference numeral  10 . Device  10 &#39;s main body portion is an elongate cylindrical barrel  12  having first and second ends  14  and  16 , and housing a  12  volt battery  18 . 
     A cylindrical head portion  20  is threadedly engaged with first end  14  of barrel  12 . Head portion  20  has a substantially hollow interior cavity  22 , and a circular lateral port  24  oriented on an axis substantially perpendicular to the longitudinal axes of barrel  12  and head portion  20 . A cylindrical, internally-threaded bushing  26  is seated in lateral port  24  against circular insulating gasket  28 . Bushing  26  is preferably dimensioned to receive a standard, threaded CATV coaxial F-connector. Bushing  26  may be threadedly engaged with head portion  20  at port  24 , or may be press-fitted in place. Locking pin is pressed in place through longitudinal channel  32  to keep bushing  26  from disengaging from head portion  20 . 
     A pin connector  34  projects axially from head portion  20  into the first end of barrel  12 . Insulating collar  36  holds pin connector securely in place. Battery  18 &#39;s positive pole abuts pin connector  34 , because coil spring  38  biases battery  18  in the direction of barrel  12 &#39;s first end  14 . 
     Printed circuit board  40  is disposed within head portion  20 &#39;s interior cavity  22 , and is in electrical continuity with pin connector  34 . Bicolor LED  42  is also in electrical continuity with printed circuit board  40 . Bicolor LED is preferably able to emit red light or green light under different conditions, further discussed below. LED  42 &#39;s lens projects through an aperture  44  in annular cap  46 , cap  46  being pressed into seated, secure engagement with head portion  20  in covering head portion  20 &#39;s open end. Elongate copper F-pin  48  is in electrical continuity with, and projects perpendicularly from, the face of printed circuit board  40 . F-pin projects through lateral port  24 , in coaxial alignment with bushing  26 . 
     Printed circuit board  40  includes the circuit  50  schematically shown in FIG. 4, the components and respective manufacturers of which are shown in the table of FIG.  5 . Printed circuit board  40  includes regulator  52 , comparator  54  and transistor  55  which, along with resistors of the values shown (not separately numbered herein) carry out the functions of device  10  set forth farther below. P 1 +12 v connector  56  is in electrical continuity with pin connector  34 . P 2  FCON connector  58  is in electrical continuity with F-pin  48 . D 1  LED connection  60  is in electrical continuity with bicolor LED  42 . 
     Electrical continuity exists from F-pin  48  through printed circuit board  40 , through LED  42 , to pin connector  34 , to battery  18  and through the case of device  10  as constructed from barrel  12  and head portion  20 . Thus, F-pin  48  and bushing  26  constitute the central and peripheral contacts, respectively, of a standard CATV coaxial cable female F-type connector. 
     Second end  16  of barrel  12  is closed with end cap  70 , which is threadedly secured or pressed into barrel  12 . End cap  70  includes a threaded, female F-type connector  72  able to receive a threaded, male F 81  connector. However, end cap  70 &#39;s connector  72  includes no axial electrical contact, and is not in separate electrical continuity with the primary circuit of device  10 , other than being part of, and therefore in continuity with, device  10 &#39;s case. 
     Toner portion  74  includes a threaded, male F 81  CATV cable connector  76  projecting from toner base  77 ; a standard 2-piece F 81  central insert  78 ; a 12-volt piezo buzzer  80 ; a ground pin  82  received by ground pin channel  84 ; piezo protection screen  86  and cylindrical case  88 . Piezo buzzer  80  is a 12-volt D.C. unit, model no. EFM-250, manufactured by Ningbo East Electronics Co. Ltd., available through Myntahl Corporation of Hayward, Calif. One of piezo 80&#39;s electrodes (not separately numbered) is in continuity with the peripheral, threaded portion of F 81  connector  76  on toner base  77 . Piezo  80 &#39;s other electrode is in continuity with central insert  78  of male F 81  connector  76 . A relieved, nonthreaded portion  90  of male F 81  connector  76  is provided at connector  76 &#39;s extreme terminus. 
     In use, device  10  is easily manipulable. It can be held in one hand, extended into a tight spot such as a crowded junction box or a mass of cables and, with a bit of finger pressure behind head portion  20 , its connector can be pressed into engagement with a cable end. LED  42  is essentially at the end of the technician&#39;s fingertip, and therefore easily viewed. 
     As shown in FIG. 6, device  10  is most conveniently fitted with an F-type push connector  92  at bushing  26  for connecting with a male, threaded F 81  connector  94  on the end of a length of coaxial CATV cable  96 . Once connector  92  is engaged with male cable end  94 , if toner portion  74  is engaged with a female-female, F-type coupling  98 , piezo buzzer  80  should emit an audible tone confirming that good continuity exists in the line. If there is a short in the line, piezo buzzer  80  will not sound, and visible confirmation of the short is issued by LED  42  glowing red. If discontinuity exists in the line, no audible confirmation from toner portion  74  is heard, and LED  42  emits no color; it remains clear. Thus, circuit  50  distinguishes between a direct short and the condition of the line when toner portion  74  is in the cable circuit. 
     If instead, as in FIG. 6, the distal cable end is fitted with a 75 ohm terminator  100 , LED  42  on device  10  would flash green, indicating proper termination. That is, where continuity exists, circuit  50  distinguishes the low resistance in the line from a direct short, and also from the condition when toner portion  74  is in the cable circuit, and causes LED  42  to glow green, rather than red. 
     In the field, use of device  10  may be as depicted in FIG.  7 . For example, from junction box  102  outside an individual room  104  in a dwelling structure, in attempting to determine to which distal cable end  108  a particular proximal-end  106  male F 81  coaxial cable connector  94  is connected, the technician would first engage device  10 &#39;s F-type push connector  92  with the proximal-end  106  male F 81  connector  94  in question. Then, the technician would enter each room  104  of the structure having a distal cable end  108 , and apply toner portion  74  to the threaded, female-female F-type connector  98  normally mated with the male F 81  connector on the back of a television set  110 . Toner portion  74 &#39;s relieved threads  90  permit the technician to press toner portion  74  into quick contact with female-female connector  98 , listening for the audible confirmation from piezo  80  that continuity exists with device  10  at junction box  102 . If no tone is heard, the technician moves to the next cable-supplied room  104 , and makes another quick check until the correct cable is found. 
     Alternatively, the technician may screw toner portion  74  into secure engagement with female-female connector  98  and then, back at junction box  102 , test each male F 81  jack at each proximal end  106  of each cable  96 . Once the technician connects device  10  with the correct connector  94 , if the technician is not too far from toner portion  74 , an audible tone from piezo  80  will be heard. If there is a splitter in the line, and if the cable branch projecting from the splitter is properly terminated with a 75 ohm splitter, the technician will see a green LED in addition to hearing the audible confirmation from toner portion  74 . 
     In yet another alternative mode of use, where the technician desires to determine which F-type female connector  98  at junction box  102  is connected to distal cable end  108  in room  104 , and where distal cable end  108  may be too far from junction box  102  for the technician to hear an audible tone, the technician may affix device  10  to distal end  108  and carry toner portion  74  to junction box  102 . In that scenario, the positions of device  10  and toner portion  74  are essentially the reverse of what is shown in FIG.  7 . That is, the technician engages device  10 &#39;s F-type push connector  92  with the distal-end  108  F 81  connector in room  104  and leaves it there. Assume, for example, that junction box  102  has multiple F-type female connectors  98  at the proximal ends  106  of cables  96 . This is most desirable, as it permits advantageous use of the nonthreaded tip  90  of toner portion  74 . At junction box  102 , the technician quickly presses toner portion  74  into connection with each female, F-type connector  98  in junction box  102 . As soon as an audible tone from piezo  80  is heard, continuity is confirmed. Failure to hear a tone from a particular line indicates that the cable engaged by toner portion  74  is not the cable connected with device  10 , or that there is a short in the line. However, if there were a short in the line, the technician would have noticed LED  42  glowing red upon application of device  10  to distal cable end  108 . 
     On other occasions, the technician may need to determine whether particular cables  96  are properly terminated with a 75 ohm terminator cap  100 . In that case, the technician needs only to apply device  10  to each proximal end  106  of each cable  96  in question at junction box  102 . Upon connection, if LED  42  glows green, proper connection to a 75 ohm terminator cap is confirmed. If a red LED is observed, the technician knows there is either a short in the cable, or that the cable is properly connected to a television  110  or other cable-supplied device. Accordingly, each such cable which produces a red flash should be checked with toner portion  74  at its distal end  108 , as described above. If LED  42  does not glow at all, the technician is informed that the line has no short, but that it is not properly terminated and that it is not connected to any television  110  or other cable-supplied device. 
     Device  10  is also adapted for testing LAN coaxial cable systems. In doing so, an adaptor having a threaded, male F 81  connector on one end and a BNC LAN connector on the other is engaged with bushing  26  of device  10 . Such F to BNC adaptors (not shown) are known and commonly available. In testing continuity of cables in LAN systems, the same procedure set forth above for CATV systems is followed. However, proper termination of a cable in LAN a system requires application of a standard 50 ohm BNC terminator cap (not shown). Thus, to accommodate LAN as well as CATV systems, circuit  50  of device  10  is adapted to produce a green LED flash if a 50 ohm resistance is sensed in the line. Thus, circuit  50  produces a green LED flash if any resistance from 50 to 75 ohms is encountered, thus giving device  10  great versatility. 
     Device  10  is given further versatility by addition of a specially-configured telephone system adaptor  112  having a threaded, female F-type connector  114  on one end, and a male RJ 11  connector  116  on the other. This special adaptor for testing twisted-pair telephone lines is shown in FIGS. 8 and 9. Male RJ 11  connector  116  of adaptor  112  is longer than the standard RJ 11  connector, molded of plastic, and has an integrally-molded, finger-depressible spring bar  118  with a barbed tip  120 . Two of the four standard RJ 11  pins in male RJ 11  connector  116  are connected to the center pin of the female F-type connector  114 , and two are connected to connector  114 &#39;s outer, peripheral connector. This permits testing two telephone pairs, i.e. lines, at once. These elements make it very easy for the technician to use telephone system adaptor  112  in conjunction with device  10  when adaptor  112 &#39;s threaded, female F-type connector is engaged with a male-male, threaded F 81  connector to bushing  26 . Male RJ 11  connector  116  of adaptor  112  is very easily manipulable: it is easy to engage with a female RJ 11  receptacle in crowded or obscure areas; it clicks in place and stays put once engaged; and, it is easy to release from the receptacle with a bit of finger pressure on spring bar  118 . For audible confirmation of continuity in a line with which device  10  and telephone adaptor  112  are engaged, a second adaptor  112  is attached to toner  74  and plugged into the end of the line opposite to that where device  10  is situated. 
     Another telephone system testing device is shown in FIGS. 10 and 11. Therein, a dual-contact USOC adapter  122  for testing a telephone  66  block having up to 50 telephone lines is shown. USOC adaptor includes a threaded, female F-type connector  124  on one side, and a push-type, dual-contact USOC-type connector  126  on the other. One contact of the USOC-type connector  126  is connected to the central pin of the female F-type connector  124 , and the other is connected to connector  124 &#39;s outer, peripheral connector. USOC telephone adaptor  122  may be used alone, or in combination with RJ 11  adaptor  112  on the opposite end of a tested line, to confirm continuity. 
     Finally, for versatility in testing other systems, or where the proper connectors or adaptors for coaxial or twisted pair systems are not immediately available, FIG. 12 shows a clip lead adaptor  128  having a threaded, male F 81  connector  130  on one end, and a pair of alligator clip leads  132  on the other. One alligator clip lead  132  is connected to the central pin-receiving channel of the threaded, male F 81  connector  130 , and the other is connected to connector  128 &#39;s outer, peripheral connector. 
     Between uses, device  10 &#39;s pocket clip  134  facilitates convenient storage in the technician&#39;s pocket. 
     A kit may be assembled from device  10 , adaptors  112 ,  122  and  128 , along with various terminator caps and standard couplings and adaptors for the types of systems to be tested. These components may be kept together in any small convenient carrying case. 
     The foregoing detailed disclosure of the inventive cable continuity testing and tracing device  10  is considered as only illustrative of the preferred embodiment of, and not a limitation upon the scope of, the invention. Those skilled in the art will envision many other possible variations of the structure disclosed herein that nevertheless fall within the scope of the following claims. 
     And, alternative uses for this inventive device may later be realized. Accordingly, the scope of the invention should be determined with reference to the appended claims, and not by the examples which have herein been given.