Have meter that reads volts. Would like to...

From: Don Bruder (dakidd_at_sonic.net)
Date: 03/15/05 

Date: Tue, 15 Mar 2005 14:54:48 GMT

Heya folks, got a cheap car voltmeter - it reads in (duh!) volts. 6-20
of 'em, to be exact. Nothing particularly fancy or ultra-accurate, just
"a voltmeter" that'll be handy for keeping a general eyeball on the
charge state of the system.

I know that a meter that reads volts and a meter that reads amps are
often constructed around the same meter movement, as is evident from the
analog VOM I've got that can read all three values of Ohm's law without
having to change the movement - just the setting of a selector.

Problem is, I've never managed to wrap my head around the "how-to"
involved in changing from one to the other. Every explanation of the
idea I've encountered leaves me scratching my head.
 
So what I'm looking for here is a way to set it up so that I end up with
a dual-purpose "When left alone, it displays volts, but when <something
- button push, switch toggle, etc> is done, it displays amps" meter. I
COULD go down to the parts store and buy its amp-reading mate, but I've
got this minor problem called "lack of place to put another one". If I
can make this one "convertable", I'd like to go that route.

What do I need to do to make a voltmeter read either volts or amps on
user demand? Obviously, I'm going to need to create/calibrate an "amps"
scale for it, but that's pure trivia - Part of the "trim" when it gets
done. I need the "nuts and bolts" at this stage. 

-- 
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
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