Author Topic: Will measuring DC on AC setting damage analog multimeter  (Read 2423 times)

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Offline lordvader88

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Will measuring DC on AC setting damage analog multimeter
« on: December 28, 2016, 01:14:27 pm »
I don't remember nor I want to check a book right now. I have a mostly working 6 tube radio from 1961 that I'm probing around  :-DMM

On a typical AMM with separate AC and DC ranges, does it hurt it if I happen to measure a lot of AC while set on DC, and vice versa ? I know its fine on my DMM
 

Offline jaromir

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Re: Will measuring DC on AC setting damage analog multimeter
« Reply #1 on: December 28, 2016, 02:32:28 pm »
The problem with higher AC voltage on DC range is that the multimeter needle will not show very much, what can lead you to switch to more sensitive range... up to the point where something may break. Measuring DC voltages on AC range is generally OK, though the measurement accuracy is totally off.
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Offline David Hess

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Re: Will measuring DC on AC setting damage analog multimeter
« Reply #2 on: December 28, 2016, 03:53:07 pm »
The problem with higher AC voltage on DC range is that the multimeter needle will not show very much, what can lead you to switch to more sensitive range... up to the point where something may break.

Competently designed digital multimeters have the same overload specifications on all AC and DC voltage ranges if only because they share the same input circuits.  For the same reason, neither AC or DC signals will cause damage if the wrong function is used.  Even the ohms ranges should be proof against damage from AC and DC signals although sometimes to a lower level because it is difficult to protect the current source from severe voltage overload.
 

Offline jaromir

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Re: Will measuring DC on AC setting damage analog multimeter
« Reply #3 on: December 28, 2016, 06:08:15 pm »
While that's true, OP asked about analog multimeters.
Those were often nothing but a galvanometer, bunch of resistors, rotary switch and rectifier.
« Last Edit: December 28, 2016, 06:09:53 pm by jaromir »
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Offline jeroen79

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Re: Will measuring DC on AC setting damage analog multimeter
« Reply #4 on: December 28, 2016, 08:18:07 pm »
a typical AMM
There are different types of analog meters, which one are you using?

As mentioned, some analog meters have lower impedance at lower range and the user could end up drawing too much AC current as he switches to a lower range.

Otherwise I don't see a problem with the AC itself unless it hits the needle's resonant frequency.
 


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