Appeal No. 95-4530
Application 08/077,993
With respect to FIG. 1, appellants disclose electric power
lines E, a ground line G and a neutral line N. Oscillator 22
feeds at least one voltage pulse into an electric line N. Line N
has a source portion short circuited to the source portion of
line G at ground potential. Induced voltage P1 advances along
line N to the end portion thereof and induced voltage P2 of
opposite polarity advances along line G to the end portion
thereof. The electric wiring state is determined utilizing a
discrimination circuit 30 by comparing the difference in polarity
between the voltage pulses at the source and end portions of the
line.
b) The Prior Art:
In FIG. 1, the Metcalf patent discloses a current sensing
circuit 42 for sensing a direction of flow of an injected current
pulse along a conductor 106 (FIGS. 2 and 3) of a circuit under
test. The conductor comprises part of a circuit, such as a
printed circuit, which has several components connected to a node
where a circuit or component fault is known to be present. A
probe 12 introduces the injection current to the conductor at the
node. The current has a triangular wave form as illustrated in
FIGS. 2(a) and 2(d) to facilitate discrimination of the direction
of current flow. A U-shaped ferrite core 46 forms part of the
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