Method and apparatus to test electric circuits

{
  "publication_number": "US5998984A",
  "country": "US",
  "kind": "A",
  "title": "Method and apparatus to test electric circuits",
  "abstract": "In order to place contour portions of an electric circuit, a local scanning curl electric shield acts on the electric circuit so as to induce an electromotive force on the electric circuit, an electric circuit is connected with a light source emitting light strobes so that in response to maximum or minimum values of the electromotive force electric strobe pulses are generated.",
  "claims": [
    "1. A method of tracing contour portions of an electric circuit, comprising the steps of connecting a light source adapted to emit light strobes to the electric circuit; acting on the electric circuit by local scanning curl electric field so that when the local scanning curl electric field intersects the electric circuit an electromotive force is induced across the electric circuit and a maximum or a minimum value of the electromotive force causes the emission of light strobes by the light source, and said light source illuminates points at which the electric circuit is intersected by the local scanning curl electric field.",
    "2. A method as defined in claim 1, and further comprising the steps of determining an instance of time when the electromotive force across the electric circuit reaches its peak value and using electric strobe pulses of the light strobes to form an electric strobe pulse when the peak value of the electromotive force occurs.",
    "3. A method as defined in claim 1, wherein said illuminating includes marking a contour of branches of the electric circuit by superimposed light pixels of different colors, depending on outgoing or incoming direction of the branches.",
    "4. A method as defined in claim 1, and further comprising separating electric strobe pulses of the light strobes into two groups, depending on polarity of the induced electromotive force; using electric strobe pulses of the light strobes of a first of the groups to trigger the emission of a strobe light of a first color; and using the electric strobe pulses of the light strobes of a second of the groups to trigger the emission of a strobe light of a second color, said first color being different from the second color.",
    "5. A method as defined in claim 1, and further comprising the step of directing the strobe lights to a viewer.",
    "6. A method as defined in claim 1, and further comprising the step of directing the strobe lights to a visualization screen.",
    "7. A device for tracing contour portions of an electric circuit, comprising means for emitting light strobes by a light source; and means for acting by local scanning curl electric field on the electric circuit so that when the local scanning curl electric field intersects contour portions of the electric circuit an electromotive force is induced across the electric circuit and triggers the emission of the light strobes by said light source.",
    "8. A device as defined in claim 7, wherein said means for acting include a disc provided with at least one local magnetic field source and spinning around an axis; and further comprising means for spinning said disc.",
    "9. A device as defined in claim 8, and further comprising an electromagnetic shield with an opening inside of said electromagnetic shield, so that no two of the local magnetic field sources can appear simultaneously inside said opening, said electromagnetic shield and said power means for spinning said disc being located on mutually opposite sides of said disc.",
    "10. A device as defined in claim 7, and further comprising a potentiometer with an input terminal connected to said electric circuit.",
    "11. A device as defined in claim 10, and further comprising an amplifier with an input connected to an output of said potentiometer.",
    "12. A device as defined in claim 7, wherein said means for emission of light strobes is formed to emit strobe lights of two different colors.",
    "13. A device as defined in claim 9, and further comprising at least one handle for moving the device so that light contours of outgoing and incoming branches of the electric circuit are reproduced when the electric circuit is placed in front of said electromagnetic shield.",
    "14. A device as defined in claim 7, wherein said acting means include magnet elements having a light-scattering surface.",
    "15. A device as defined in claim 14, wherein said magnet elements are arranged on a disc so that each of said magnet elements produces a magnetic field essentially normal to said disc.",
    "16. A device as defined in claim 14, wherein said light-scattering surface is formed as a convex mirror having a generally round surface."
  ],
  "description_excerpt": "This invention relates generally to electrical circuit troubleshooting, and more specifically, to inductive testing, tracking, or tracing of electric circuits.\n\nThe problem of an electric circuit tracing exists in electrical engineering in various applications including applications related to troubleshooting and reverse engineering. One tracing technique, known as inductive tracing, is based on inducing electric voltage driven by an alternative current that passes through a traced circuit. The circuit path is traced by detection of the induced electrical signal by a receiving coil, and with further measurement and indication of intensity of the induced signal that gives information about position of the traced conductive wire portion. In prior art, U.S. Pat. No. 5,457,441 to Clement discloses an inductive tracer that amplifies an electrical signal induced in a detecting coil or sensor. U.S. Pat. No. 4,801,868 to Brooks discloses a circuit tracing apparatus and method based on receiving low frequency RF signal driven by a transmitter plugged into a power line under test.\n\nThere are certain drawbacks inherent in the named prior art. The inductive tracing requires passing alternating current of relatively high frequency to get a sufficient induced voltage in the circuit tracing device. The high frequency current causes undesirable displacement current to flow through capacitors, resulting in detection of false branches of a circuit that have no DC-conductivity.",
  "cpc": [
    "G01R 31/315"
  ],
  "ipc": [
    "G01R 31/315"
  ],
  "inventors": [
    "Mark Krinker",
    "Ilya Stein"
  ],
  "filing_date": "1997-12-14",
  "publication_date": "1999-12-07",
  "grant_date": "1999-12-07",
  "priority_date": "1997-12-14",
  "application_number": "US-99021897-A",
  "family_id": "25535909",
  "cited_by_count": 3,
  "citations": [
    "US4775832A",
    "US4801868A",
    "US5365163A",
    "US5457441A"
  ]
}