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US 5,293,113 AGranted
Test instrument for the display of electric voltages
AssigneeCh. Beha BmbH
InventorsChristian Beha, Martin Schwartz
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AssigneeCh. Beha BmbH
InventorsChristian Beha, Martin Schwartz
Estimating the term…
A testing device for single-pole voltage testing comprises, between a test electrode (1) and a ground electrode (2), a high impedance dropping resistor (R1) and a measurement resistor (R2) connected in series. The ground electrode (2) is capacitively coupled to earth through the body of the user. The value of the dropping resistor (R1) is at least 10 times greater than the maximum variation which occurs in the capacitively coupled reactance (C1, C2) of the user relative to the ground, so that the total impedance is almost constant. The voltage drop across the measurement resistor (R2) is amplified, rectified and compared in a comparison circuit with predetermined reference voltages in order to control a light emitting diode indicator (D2, D3, D4, D5) corresponding to the measured voltage. The test device can also be constructed for contactless voltage testing or can also be used as a continuity tester.
A single probe, alternating current voltage testing device comprising a test electrode, a grounding electrode electrically coupled to a user, said user being connected to ground by capacitative reactances, a series resistor circuit comprising at least first and second resistors in series between said test electrode and said grounding electrode, with said first resistor being connected to said test electrode and said second resistor being connected somewhere in said series resistor circuit between said first resistor and said grounding electrode, and means for providing a plurality of reference voltages for comparative purposes, wherein the first resistor has an impedance which is at least ten times as great as the total impedances in series with said series resistor circuit, said impedances in series with said series resistor circuit being, first, any impedance between an object to be tested and said test electrode, second, any impedance existing between said grounding electrode and said user, and, third, any impedance existing between said user and ground, and wherein the second resistor is a measurement resistor across which a voltage is derived for comparison with said reference voltages.
Dependencies are inferred from the claim text.