Smoke Detector

Smoke Detector is a device to fight against the smoke. By using ionization or photoelectric technique, the presence of the smoke is detected by the device. The components used include a photoelectric smoke detector, encoder, decoder, transmitter, receiver and siren. The relay is built in the smoke detector. On detecting the smoke, the relay is triggered. The relay then connects the transmit enable (TE) pin of the HT-12E encoder to ground causing the encoder to send a digital output to the transmitter. Apart from that, several smoke detector is one of the important things in placing them in the building. Even small buildings need more than one smoke detection system. The exact number depends on two things which are the number of levels in the building and the number of rooms. A house newly constructed requires a smoke alarm in each bedroom, one outside the bedroom area that is close enough to be heard through closed doors and a minimum of one on each level of the home. The objective of having a smoke alarm outside the bedroom area is to alert the sleeping occupants of a fire that starts outside of the bedrooms. Incase the bedrooms are located in different areas, then each area should have its smoke alarm. If a home is large, it is better to use more than one on each level. The closer the smoke alarm is the faster it will work. Moreover, the smoke detector should not be placed in garages for two reasons. First, garages are usually not heated or cooled. Sometimes, it is above or below the temperature range. Second, the smoke from engine exhaust fumes causes alarms and activates the smoke alarm. The HT12E is used for remote control application. It can encode N address bits and 12-N data bits information. The wireless smoke detection system is tested indoor and outdoor with smoke, noise, heat and flame itself. For the indoor test, a positive response is received for the first 70 meters because the signal fails to transmit over 80 meters onward. Even the distance between transmitter and receiver are tested in the building with the smoke and the presence of noise. Positive respond is recoded for the first 70meters. This result indirectly indicates that the noise is considered as a small interruption for signal transmission. On testing the system with heat and flame, negative results are recorded all over the range of distance due to the sensitivity of the smoke detector towards flame and heat. While for outdoor testing, the same procedures are used.

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