Small question about Voltmeter.

[alphacat]

Hey,

I wanted to ask please, does a voltmeter know what is the + and what is the - of the DUT by sensing the direction of the current which flows through it when connected in parallel with the DUT?

Thanks.

 

[crutschow]

It simply senses the polarity of the voltage, not the current. It likely senses whether the input is positive or negative with respect to the common lead with a comparator and adjusts the input polarity to the voltmeter circuit so it measures the voltage properly.

 

[alphacat]

Thanks.

Isnt the voltage polarity set by the current flow's direction?

--
I mean, i thought that the only way to determine the voltage's polarity was to check the flow direction of the electrons.

 

[BrownOut]

Thanks.

Isnt the voltage polarity set by the current flow's direction?

--
I mean, i thought that the only way to determine the voltage's polarity was to check the flow direction of the electrons.

On a microscopic level, that's true. However, we think of things like comparators and op-amps as voltage devices. It just makes analysis easier.