User manual

and put the two measuring prods of the measuring lines together. The display
shows 0.0 Ω, meaning "no impedance" (line passage). Moving the two test prods
apart increases the impedance to infinite and the multimeter shows "1—". This
means "no passage" or a cable break. Try determining the line passage for
different cables.
To determine the line passage, a cable must be powered down.
It must not be connected to any power source!
Figure 50: Holding the two strings together will cause the multimeter to show
0.0 Ω or 0.01 Ω when impedance measurement is set. This means that line passage
is present, which equals nearly no impedance.
Figure 51: Moving the strings apart turns the impedance infinite, which is
displayed as "1—". This would mean cable break or wires not found in a multi-
core cable.
Figure 52: Determination of the line passage at a cable.
Measuring in a Circuit: Determining Individual Voltages at Components
Set up a combined circuit where you switch the two 1 kΩ resistors in parallel
and in series to the two 330 Ω resistors before installing the LED. This ,leads
to a circuit with four consumers where you can measure the individual voltages.
Touch the two measuring strings to the two connection wires of each resistor and
the LED each.
You will find that the two 330 Ω resistors show the same voltage drop (1.59 V).
The two resistors switched in parallel are to be considered one, so that you
will only measure a "quasi mutual" voltage drop. No matter if you determine the
voltage drop at the 1 kΩ resistors individually or as a parallel circuit - it is
always the same. In our example, it is about 2.41 V. The LED shows a voltage
drop of about 3.2 V.
Figure 53: Mixed LED circuits of two parallel 1 kΩ and two serial 330 Ω
resistors; the circuit also shows the possible measuring points.
Figure 54: Circuit of a mixed serial and parallel circuit controlling an LED.
Figure 55: No matter where the voltage drop is measured at each individual one
of the two resistors switched in parallel or all of them together - it is always
of the same size.
Figure 56: The same voltage drop will occur at two equally sized resistors in
series.
Measuring Resistors in a Circuit
When measuring individual resistors in a circuit, always observe whether any
other components may be switched in parallel with them that may be measured as
well. For example, this occurs in case of resistors switched in parallel. You
may only determine the overall impedance for them. If you want to measure the