side. The difficulty now is the parallel paths
around the resistor. To take these parallel
paths out of the measurement, place a
ground in the center of each path. With a
ground on both sides of a resistor, there is
no voltage drop across the resistor resulting
in an effective open. The precise value of
the resistor is calculated by dividing the
source voltage by the current. In this case,
1V divided by .213 mA equals 4. 7 kΩ.
The position of the source, ammeter,
and grounds can be repositioned to
measure any of the resistors without the
need of breaking the circuit.
Figure 3 shows how the circuit can be
reconfigured to measure the bottom left
resistor. It is important to remember that
just because the parallel paths are taken
out of the measurement, doesn’t mean that
the parallel current paths are eliminated.
Care must be taken not to damage any
parallel components. It is recommended to
use as low a voltage as is possible.
Now, it’s time for a challenge to show
how you would connect the circuit in
Figure 4 to accurately measure the other
Find the answers on the next page ...
By Richard Agard
July 2016 57
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