Questions according DMM

[Tony Clark]

On 9 Nov 1999, Karsten Welskop wrote:

> Hello,
> 
> I'm new to the DIY World. I would like to buy a DMM, but I dont know
> exactly what features are necessary and which not. Espacially I would
> like to know what does 3, 3 1/2 or 3 3/4 display means.

   I don't think this part was answered...

   The 3 refers to total number of digits, while the 1/2 or 3/4 is an 
indication of its leading digit reading capability.  For instance, a 3 
1/2 meter has a top scale of 2 in whatever range it is reading in (i.e. 
1.99, 19.9, etc).  A 3 3/4 meter has a top scale of 4 (i.e 3.99, 39.9, 
etc).
   There are times when having both a 1/2 and 3/4 meter are handy, but I 
doubt many people bother to buy one of each (I haven't!).  So what I 
would do is figure out what the average signal you are planning to look 
at is and then choose the scale based on that.  Personally though, I'd 
look for a 4 1/2 or 4 3/4 meter, not a 3.  The extra digit is extremely 
useful when trying to read a dynamic range of signals without loosing 
accuracy.
   There are a number of good DMM manufacturers out there, its just a 
matter of choosing the features you want.

   Tony


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