Basic Meter Theory

[DavidGriffin]

Neil,
Yes, that's the simplest way to view it and it worked.  I just now replaced 
a f.s. 3 ma meter with a 10 ma f.s. meter and all is working fine.  Thanks 
very much.   Replacing a meter with one of higher f.s. can work....and in my 
case did....depending upon the meter resistance.  I measured the original 
meter resistance at 3K and the replacement meter was 1200 ohms.
Thanks to Bob and Ed for the detailed views,  too.
Also, I eventually did find a basic tutorial  at
http://www.electronics-tutorials.com/test-equip/meter-shunt.htm
where you can find the formula I mentioned in my first post.
But it doesn't explain it as well as you folks did.
73
Dave


----- Original Message ----- 
From: "Neil Morrison" <neilsmorr at gmail.com>
Sent: Friday, August 11, 2006 11:57 PM
Subject: Re: [HEATH-TEMPE] Basic Meter Theory


>
> FWIW, a rule of thumb is that most meters drop about 0.3 volts. What is 
> the FS mA of the new meter?
>
> Example:
>
> Old meter
> mA 5
> Ohms 60
> New meter
> mA 23
> Ohms 150
>
> So add 100 ohms in parallel.
>
> Neil
>
> ----- Original Message ----- 
> From: "DavidGriffin" davidgriffin at CISBEC.NET
>
> Hi folks,
>
> Can't remember my basic meter resistance theory.  Want to replace a meter 
> that would normally read 5 ma with another meter of a different f.s. 
> Can someone please point me to a basic tutorial on the net in regards to 
> this? I seem to remember some years ago calculating and/or measuring meter 
> resistance and using formulae to calculate resistors, etc.  But the mind 
> is rapidly deteriorating.
>
> Thanks,
>
> Dave
> n2chi
> 

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