Question about Analog multimeter accuracy

planetElectron

Joined May 5, 2022
17
Hi,
Can someone explain me what are F.S. and arc in Accuracy specs of an Analog multimeter because I'm uncertain about them.
For example, ±3% F.S., ±3% of arc,
marked blue in picture.

Attachments

• 393.7 KB Views: 20

Alec_t

Joined Sep 17, 2013
13,153
FS is full scale.
arc presumably is the angular range through which the needle can sweep.

Marley

Joined Apr 4, 2016
489
FS is Full Scale.
I think they use "arc" for the resistance ranges is because they specify the accuracy at half-scale.
Full scale on resistance is infinity. What is a percentage of infinity? (!)
So the accuracy is % of the number of degrees.
BTW: Some think that meters with a digital readout are more accurate. Not necessarily true! Just because the display says 1.334V (for example) does not mean that it is correct to the last (or any) digit!

Lo_volt

Joined Apr 3, 2014
275
Just because the display says 1.334V (for example) does not mean that it is correct to the last (or any) digit!
This is true! Check the spec sheet of your meter to find out exactly how accurate the reading is.

KeithWalker

Joined Jul 10, 2017
2,518
For ±3% of arc read ±3% of deflection (displayed value).

crutschow

Joined Mar 14, 2008
30,791
Since it's a log scale, I think 3% of arc means 3% of the reading on the ohm's scale.

Last edited:

crutschow

Joined Mar 14, 2008
30,791
Full scale on resistance is infinity.
Full scale on a standard analog multimeter is 0 ohms.

planetElectron

Joined May 5, 2022
17
Thanks to everyone, just to be sure,
if 1000 DCV range (±3% F.S.) is selected,
then 3% of full scale 1000, 30 should be added/subtracted to/from reading values?

Last edited:

crutschow

Joined Mar 14, 2008
30,791
then 3% of full scale 1000 = 30 should be added/subtracted to/from reading values?
It means the actual value can be anywhere within ±30 of the meter reading.

That relatively low accuracy (and low resolution) is why digital meters are usually preferred over analog meters.
The only advantage of a analog meter I see, is that you can more readily follow a slowly changing voltage.

planetElectron

Joined May 5, 2022
17
It means the actual value can be anywhere within ±30 of the meter reading.
That is exactly what I mean,
Thanks and sorry for my broken English.

crutschow

Joined Mar 14, 2008
30,791
That is exactly what I mean,
Thanks and sorry for my broken English.
Okay, I just wanted to clarify that.
Your English is fine.