US 4,301,407 AGranted

Hand held testing device for indicating an electric test voltage

AssigneeSiemens Aktiengesellschaft

InventorManfred Koslar

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Abstract

There is disclosed a hand-held testing device for indicating different values of an electric test voltage. The testing device comprises at least one grip body adapted to be held in the hand and an electric circuit arranged therein. The grip body has a testing tip forming an input connecting point of the electric circuit adapted for receiving a test voltage and has a ground connection. The voltage divider connected between the connecting point and the ground connection has at least two ohmic resistors connected in series via a respective connector tap. Furthermore, the electric circuit has a plurality of display stages, each stage being connected to a respective connector tap of the voltage divider. Each display stage has a two-state amplifying element responsive to the voltage at the respective connector tap and has an optical display element indicating the presence of a given test voltage which is received at the connecting point. The display stages are interconnected by the outputs of the amplifying elements, such that only the amplifying element of the display stage which corresponds to the value of the given test voltage is switched on.

Claims15

Dependent claims

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.

9 more elements

Dependencies are inferred from the claim text.