3B SCIENTIFIC PHYSICS AM51, Instruction Sheet

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4.4 Current measurement
•
When taking any current measurements
connect the multimeter in series to the load
in the circuit, which has the least potential
with respect to ground.
•
Measurements conducted in the 3 A range
may not take longer than 1 min.
4.4.1 Direct current up to 1 A
•
Using the rotary switch (1) select the corre-
sponding measurement range “1 A,...,50 μ A
DC”.
•
Connect the multimeter and take a reading
on the V, A, DC scale.
4.4.2 Alternating current up to 3 A
•
Using the rotary switch (1) select the corre-
sponding measurement range “3 A,..., 3 mA
AC”.
•
Connect the multimeter and take a reading
on the V, A, AC scale.
4.5 Measuring resistance
•
Using the rotary switch (1) select the corre-
sponding measurement range “x 100 Ω ,..., x
1 Ω ”.
•
Connect the multimeter and take a reading
on the Ω scale.
•
When performing measurement on semi-
conductors use the following terminals: posi-
tive pole connected to “COM” and negative
pole connected “A A,
Ω ”.
•
Resistance measurement is carried out us-
ing the DC voltage from the battery being
used. Since the battery is under extreme
loading during measurements in the “x 1
Ω ”
range, the measurement should only be of a
brief duration.
•
Only measure zero-voltage elements due to
the fact that external voltages falsify meas-
ured values.
•
When resistances measurements are car-
ried out involving longer periods and switch-
over to other measurement ranges is com-
plete check for 0
Ω full scale deflection and
adjust, if necessary.
4.6 Attenuation and gain measurement
•
In communications engineering the gain or
attenuation of a signal is specified in deci-
bels as the logarithm of the ratio between
the measured voltage and a defined refer-
ence voltage. Positive values correspond to
a gain and negative values reflect attenua-
tion. The reference voltage of the multimeter
amounts to 0.775 V (= 1 mW at 600
Ω ). With
this voltage there is a gain of 0 dB.
•
Using the rotary switch (1) select the corre-
sponding measurement range “600,..., 10 V
AC”.
•
Connect the multimeter and take a reading
on the dB scale.
•
Since this scale is only valid for the 10 V
measurement range, in the other measure-
ment ranges a relative constant must be
added to the value obtained from the scale:
Measurement range Constants
30 V 10 db
100 V 20 db
300 V 30 db
600 V 36 db
5. Maintenance
5.1 Storage, cleaning
•
Keep the equipment in a clean, dry and
dust-free place.
•
Only use a paintbrush or soft towel to clean
the multimeter. If static electrical charging
occurs on the view window this can be
eliminated using a damp rag or an antistatic
agent.
5.2 Battery
•
Test the battery from time to time. If it is
dead or it has started to decompose, it must