[sdiy] DMM Question (Newbie Alert!)

[Paul Schreiber]

Because in the dark ages of electronics (before you were born, say 1973 or 
so) every digit on a DVM implied that decade was accurate for all counts 
0-9). But, HP thought of a clever way to "cheat" Keithley (at the time their 
arch-rivals). They began using the marketing term '1/2 digit' for a 0 or 1 
*only* display. So, a DVM that could show 1999 as the "biggest number" in 
the display, HP called that '3 1/2 digits'. So, it order to have correct 
ranges, everything started with a 2: 2V, 200mv, etc.

Paul S.

----- Original Message ----- 
From: "Sam Ecoff" <secoff at execpc.com>
To: "sdiy DIY" <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, August 27, 2009 10:37 PM
Subject: [sdiy] DMM Question (Newbie Alert!)


> Hi All,
>
> In order to reduce my newbie-ness and educate myself, I'm picking up  some 
> EE classes at the local tech college. It's fun and keeps me off  the 
> streets. While in lab measuring resistors today, a question  occurred 
> which the professor was unable to answer, so I'm asking here...
>
> I get that a DMM provides different ranges settings for measuring  various 
> resistances with greater accuracy, and I understand that each  range 
> setting on the dial represents a different power of 10. What I  don't 
> understand is why the settings are marked 2M, 200k, 20k, 2k and  200 
> rather than 1M, 100k, 10k, 1k, and 100. Can anybody help me figure  this 
> out?
>
> Thanks,
>
> Sam E.
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