Digital Multimeters for Dummies

["inman at interpath.com" at interpath.com]

Subject:  Digital Multimeter Basics / Questions 

I am considering asking Santa Claus for a jazzy multimeter for Christmas.
It is possible I may get one.  I’m 31 and it has come to my attention that
Old Man Claus is not very careful about his Naughty / Nice record
keeping, after all.  With that in mind, I have a few questions about
digital multimeters.

The Count:  The higher the count, the better because this is the number
of samples used to calculate the measurement.  True or false?

True RMS:  True root mean square.  If it doesn’t say true RMS, it is
making measurements how?  Is this cheap alternative measurement
system really that awful?

Percent Accuracy:  What is completely unacceptable for high quality
amateur work?

Certificate of Calibration:  Do I need this if I am not designing circuits
for the military or a medical life-saving equipment?  Are multimeters
so poor that one should pay extra to guarantee that the multimeter
does what the maker claims... and then take the maker’s word on it?

Autoranging vs. Manual Setting:  I assume that setting the initial 
comparison, either automatically or manually, ensures a closer
measurement and reduces error.  But, what is the advantage
of one versus the other... or is it the same difference as automatic
versus manual transmission in cars?

Frequency:  Is this really a useful function on a handheld multimeter
or I am a better off matching pitch using my Boss guitar tuner?  Or,
is this function useful in a completely different way?

3 1/2 Digit:  Does the half digit at the end mean that measurements
are rounded to one decimal place?  I saw a Fluke with 3 3/4 digits.
What does the 3/4 digit mean?


Two general questions...

Multimeters, even those with the same features (accuracy, functions, 
etc...), seem to range wildly in price.  Are you paying for a real
difference in quality or are you paying extra for a brand name
that doesn’t really mean anything?

Is it possible for a low cost multimeter to really be good at a large
number of functions, from DC to AC, to transistor testing, to
resistance, capacitance, and frequency?  Or, is it the case with
multimeters that the do-it-all unit is a “jack of all trades and 
master of none?”


Thanks for the Advice,

Elliot
“November:  Time to Start
Being Nicer and Pull Up
My 1998 Average”