wireless monitoring system of gas detector - Faculty of Electrical ...

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Figure 3.8 show the output circuit diagram which act as the alarm system to the
system. Red LED and buzzer are connected in the same pin from the Arduino, 13. Same
as the yellow LED and exhaust fan at the pin 11. At the same time, pin 11 includes the
relay circuit act as a switch tothe exhaust fan. All the LEDs are covered with a light
transparents casing in previously shown in Figure 3.3 to give visibility to the brightness
when the LEDs light up. The output for pin 12 from Arduino is green LED only.
9V
5V
3 4
normally open
2
1
normally closed
5
RELAY
R
11 Transistor
exzos
fan
Figure 3.9: Relay Connection Circuit Diagram
Figure 3.9 show the relay connection circuit diagram from the Arduino to the
exhaust fan.Relay is need in this project because exhaust fan require a 9V battery. Relay
is an electromagnetic device that works on the magnetic field interfacing. Relay should
be checked first before making the connection circuit to test whether the connection in
the normally open or closed by using multimeter. If the multimeter sounds up with a
„bit‟ that‟s mean the pin in the normally closed. Meanwhile, if the connection pin 2 and
4 are tested, no sound will be heard at the multimeter. Exhaust fan is connected at the
normally open pin because it will be turned on when it gets the information from
Arduino pin only. Therefore, pin 5 at the relay will be not connected with any
component in the circuit.