Page 161 - Testing Electronic Components
P. 161
Figure 1 show a basic relay circuit. If there is an input signal going to the
base of transistor, the transistor will conduct and the 12V will flow
through the relay coil, the collector, out from emitter and to ground (0V).
This will energize the relay coil and cause the armature to switch from
the normally close (NC) to normally open (NO). When the armature
in the normally open (NO) state, no current will flow to the lamp (load)
and the lamp will go off.
There are two steps to test relay, first use your analogue meter set to X 1
Ohm and place across the relay coil as shown from the photo in next
page. This is to make sure that the relay coil is not open circuit. If it opens
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