The 6 1/2 digit display of DMM showing us far left digit from 0-1, and if not, why?

Thread Starter

drejc

Joined Jan 18, 2017
2
The half digit part means the far left digit only goes from 0-4, so a 6 1/2 digit display can show a range of 0 to 4999999 counts.
Hi, i'm fresh in this area but isn't 6 1/2 digit display showing us far left digit from 0-1? And if not, why?


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Reloadron

Joined Jan 15, 2015
7,480
Full Digit
Digital meters are typically described as having “half digit” capability. A full digit is a display segment that can render all the numbers from 0-9, that is 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.

Half Digit
A half digit can display only the number 1. The half digit is always the first digit shown. Because the half digit is basically only a “1” it has limited possible use.
Quotes taken from: http://www.spellmanhv.com/Technical-Resources/Application-Notes/AN-15

For example a DMM may have a 20 volt range and full scale is 19.999 which would be a four and a half digit display. The half digit is a one and only a one. The zero is not used that I have seen. Using the above example for example five volts would read 5.000 and nine point nine would read 9.900 but at ten volts the reading would display the left most one reading 10.000 volts.

Ron
 

MrAl

Joined Jun 17, 2014
11,342
Hi, i'm fresh in this area but isn't 6 1/2 digit display showing us far left digit from 0-1? And if not, why?


Moderators Note:
Please don't hijack other member's thread, now you have your own.
This thread was split from DMM digit accuracy.
Hi,

To add a little...

Yes, the left most digit can only be a 0 or a 1, not a 2, not a 3, etc.
A couple examples of readings you might see on a meter like that:
1.234567
12.34567
1234567
2.34567 (note only 6 digits now, with the leading zero blanked 02.34567)
23.4567 (again only 6 digits)
20.0000 (only 6 again)
19.99999 (back to 6 1/2 because the reading is under 2000000 counts)

Four readings you might see in succession with a very very slowly increasing voltage:
19.99998 (full 6 1/2 digits)
19.99999 (full 6 1/2 digits)
20.0000 (lost one digit, or rather that 1/2 digit)
20.0001 (lost one digit)
 
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