User manual

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output terminal which can then be used to activate any number of devices. For the
purpose of this exercise, a small green LED will turn on when the sensor becomes
active [9].
a) b)
Figure 3.20 : a) Output distance sensor characteristic [10] b) Distance sensor (IR
proximity sensor) [22]
iv. Relay
A relay is an electrically operated switch, simplest, easiest and useful device.
Most of relays use an electromagnet to operate a switching mechanism mechanically.
It contains electromagnet (coil), switch and spring. In this project, it is necessary to
control a circuit by a low-power signal that needs electrical isolation between control
and controlled circuits. Relay is a medium between the microcontroller circuit and
power lighting circuit. It also used when several circuits must be controlled by one
signal. Contactor is another type of relay that can handle the high power required to
directly control an electric motor. There are much type of relay which is protection
relay, solid state relay, reed relay, contactor relay, latching relay, automotive relay