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Data bus test instrument having a tri-colored LED and indicating continuity, voltage and polarity

  • US 4,550,287 A
  • Filed: 08/11/1983
  • Issued: 10/29/1985
  • Est. Priority Date: 08/11/1983
  • Status: Expired due to Fees
First Claim
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1. An instrument for testing an electrical circuit, said instrument indicating (1) the presence of data bus signals in a circuit, (2) whether such data bus signals are of a low speed or a high speed nature, (3) continuity of a circuit, (4) voltage in a circuit, and (5) the polarity of a DC voltage in a circuit, said instrument comprising:

  • first (24) and second (26) terminals connectable to the electrical circuit to be tested;

    a first circuit leg (A) comprising a first junction (28), a second junction (30), and a third junction (32), wherein said first junction (28) is connected to one of said terminals, and wherein said third junction (32) is connected to the other of said terminals;

    ballast means (40) connecting said first (28) and second (30) junctions, said ballast means (40) including voltage indicator means for indicating the voltage of said circuit being tested;

    a tri-color LED (38) connected between said second (30) and third (32) junctions;

    a second circuit leg (B) connecting a fourth junction (54) to said first circuit leg (A), said second circuit leg (B) including a first unidirectional conductor (50) having a certain resistance and being connected between said fourth (54) and said second (30) junctions, said first conductor (50) permitting electrical current to flow only in a direction from said fourth junction (54) to said second junction (30), and a second unidirectional conductor (52) having a certain resistance and being connected between said fourth junction (54) and said third junction (32), said second conductor (52) being operable to permit electrical current to flow only in a direction from said fourth junction (54) to said third junction (32); and

    a third circuit leg (C) including a switch (22) and a battery (64), said switch (22) serially connecting said battery (64) to said first junction (28), and with said battery (64) also being connected to said fourth junction (54).

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