MEASURING CURRENT

MEASURING CURRENT
You will rarely need to take current measurements, however most multimeters have
DC current ranges such as 0.5mA, 50mA, 500mA and 10Amp (via the extra banana
socket) and some meters have AC current ranges. Measuring the current of a circuit
will tell you a lot of things. If you know the normal current, a high or low current can
let you know if the circuit is overloaded or not fully operational.
Current is always measured when the circuit is working (i.e: with power applied).
It is measured IN SERIES with the circuit or component under test.
The easiest way to measure current is to remove the fuse and take a reading across
the fuse-holder. Or remove one lead of the battery or turn the project off, and
measure across the switch.
If this is not possible, you will need to remove one end of a component and measure
with the two probes in the "opening."
Resistors are the easiest things to desolder, but you may have to cut a track in some
circuits. You have to get an "opening" so that a current reading can be taken.
The following diagrams show how to connect the probes to take a CURRENT reading.
Do not measure the current ACROSS a component as this will create a "short-circuit."
The component is designed to drop a certain voltage and when you place the probes
across this component, you are effectively adding a "link" or "jumper" and the voltage
at the left-side of the component will appear on the right-side. This voltage may be too

high for the circuit being supplied and the result will be damage.

Measuring the current of a globe