Radio Shack 22-174A - Measuring DC Voltage; DC Voltage Measurement Procedure

Notes:
o
The meter displays the overrange indication or 0 if it
blows
a
fuse
while
measuring
current.
o
lf the
meter
displays the overrange
indication
when
you
measure
AC
current, and the circuit does
not
exceed the AC
current
in
the
present
range,
the
circuit
is
exceeding the
meter's DC
rating.
For
example,
if
you
try to measure a DC
power
supply's
AC
ripple
currenl,
the signal has both an
AC and DC compo-
nent. lf
the
DC component exceeds the
meter's rating, the
meter
displays
the overrange
indication.
To measure this
current,
you
must
externally
block the
DC component.
The AC
current
modes do
not
use
an AC coupling capacitor
to
block
DC. Both
DC
and
the
AC
current
llows through the
shunt
resistance.
Too much DC current
overpowers the
AC
component.
lf
you
need to
measure the
AC
component
of a
DC signal,
we
suggest
you
use a
high-quality capacitor
to
block
the DC component.
For normal
AC line frequencies,
we suggest
you
use a .47
pF
or
larger capacitor.
MEASURING
DC VOLTAGE
WARNING:
DO NOT
TRY
TO MEASURE
A
VOLTAGE
GREATER
THAN
1OOO
VOLTS
DC AND
750
VOLTS
AC
.
(RMS).
YOU
MIGHT
DAMAGE
YOUR METER
AND EXPOSE
YOURSELF
TO
A SEVERE
SHOCK HAZARD.
Follow
these
steps to measure
a DC voltage.
1.
Set the function
control to
Y.
mv appears
on the
display.
2.
Plug
the black
test lead
into
the meter's
-
COM
terminal
and
plug
the
red
lead
into
the meter's
i
terminal.
rM
-cou
* &
--"@flQ^@w
-- ------t
T
Black
Red
3.
Connect
the black
test
probe
to the
COMMON
point
for the voltage
to be
measured.
Connect the
red
test
probe
to
the
volt-
age
you
want
to
measure.
When
you
measure
DC
voltages,
the
minus
sign
(-)
appears if
you
connect
the black
test
probe
to a
point
in
the circuit
that
has
a higher
voltage
potential
than the
point
where
you
con-
nect
the
red
test
probe.
Note:
The
meter
does not measure
DC using
dBm. lf
you
try to
select
dBm, the meter
switches to AC measurements.
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