Measuring instrument for determining a positive or negative voltage present at a measuring input

摘要

A measuring instrument for determining a positive or negative voltage present at a measuring input (1) with respect to earth, which is of simple circuit configuration, can be electronically easily integrated and is correspondingly rugged and easy to handle and is suitable, in particular, as a polarity tester for medical applications, is characterised by a measuring stage (2) exhibiting the measuring input (1), possibly with an amplifier (3), a polarity selection stage (4) following the measuring stage (2), possibly an amplifier stage (5) following the polarity selection stage (4) and an indicating stage (6) following the amplifier stage (5), the stages being connected to earth and to a voltage supply (7) and the voltage supply (7) being capable of outputting a positive and/or a negative supply voltage, particularly U1 = +12 V, U1 = -12 V, in which arrangement a voltage present at the measuring input (1) can be measured by the measuring stage (2) and possibly amplified, the signal output by the measuring stage (2) can be selected with respect to polarity (the sign) in the polarity selection stage (4), can be amplified in the amplifier stage (5) and polarity-specifically indicated in the indicating stage (6). The measuring input (1) of the measuring stage (2) is followed by a filter (10), constructed as low-pass filter with a maximum cut-off frequency of 40 Hz, for filtering out interfering voltages so that, in particular, a [lacuna] captured by a human body as antenna ... Original abstract incomplete. <IMAGE>