Star Tech Journal

0
March 1997
Where else can you buy a fuse, a
resistor, a bridge rectifier or a
transistor on a Friday night to get
that hot pinball back in service
for the weekend? Radio Shack
makes a couple of pretty nice
meters worth looking at, and the
catalog has a nice feature chart
to help you compare the models.
What case style do you want? In
the old days, a bench meter
meant something with a lot more
features and much better perfor-
mance than a portable. These
days, it pretty much only means
the shape. At least at our level
that's the case. A bench meter is
made to sit nice and stable on a
flat surface like a bench or the
riser or shelf. A portable meter
can be the traditional handheld
rectangle or it can be the small
probe type. The 8" rectangles are
the most common and are really
the focus of this article. They
have the largest range of features
and performance. The probes
tend to be very basic with lim-
ited features, but I find them very
handy in the field. I wouldn't get
STAR*TECH
one if it was my only meter
though. I like the probe, my part-
ner thinks it beeps too much.
Journal
efore you
buy a
- ~ meter with
autoranging,
check out the
ranging speed.
Some meters,
mostly cheap
ones, are so slow
they
jl..fit ... drive ... you ... nuts!
at least. Some very basic meters
have no current ranges or limited
ones. The current ranges let you
troubleshoot fuse blowing and
overheating type problems. Con-
tinuity buzzer is usually there if
the diode test is there. While I
think continuity test is handy, I
consider the diode test an abso-
lute necessity. I wouldn't buy a
meter without it. The diode test
also checks transistors, SCRs,
triacs, and so on. Since the diode
test uses a voltage high enough
to turn on a semiconductor junc-
tion, the resistance ranges on
these meters is usually a low volt-
age type. This means you can
take resistance readings around
a circuit without confusing things
by turning on the junctions
nearby.
What does he know. How about
those features? All the meters
have the basics: AC and DC
volts, resistance, and usually AC
and DC current. Now we start
adding features. I definitely want
the high current range. Ten amps
How about them extra features?
Transistor test. Well, since I can
easily test the two junctions in a
transistor with the diode test,
what does this do for me? The
transistor test usually measures
the gain of a transistor. Note that
the test usually requires you to
... continued on page 70
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