×

Hand held testing device for indicating an electric test voltage

  • US 4,301,407 A
  • Filed: 10/22/1979
  • Issued: 11/17/1981
  • Est. Priority Date: 10/26/1978
  • Status: Expired due to Term
First Claim
Patent Images

1. A hand held testing device for indicating different values of an electric test voltage, said device comprising(a) at least one grip adapted to be held in the hand;

  • and(b) an electric circuit, arranged in said grip body, said circuit including(1) a connecting point, adapted for receiving a test voltage;

    (2) a ground connection;

    (3) a voltage divider being composed of a plurality of ohmic resistors connected in series and having a connector tap connecting each two adjacent ones of said resistors;

    said voltage divider being connected between said connecting point and said ground connection;

    (4) a plurality of display stages, each stage including a non-linear operating differential amplifying circuit and a diode, each stage being associated with a respective one of said connector taps and indicating the presence of a given value of said test voltage applied to said connecting point;

    each of said amplifying circuits having a control input connected to a respective one of said connector taps of said voltage divider, a voltage supply input and an output;

    said diodes of said plurality of said display stages being arranged in series such that each diode except for the one forming the last diode of the series connection is connected between the outputs of respective ones of two adjacent amplifying circuits, wherein only one of said amplifying circuits is switched on at a time under control of a respective threshold of a present test voltage; and

    (5) a voltage supply having an output of one polarity commonly connected to said voltage supply inputs of said amplifying circuits and an output of opposite polarity connected to said last diode of said series connection of said diodes.

View all claims
  • 0 Assignments
Timeline View
Assignment View
    ×
    ×