Somke detector project presentation

1. Smoke Detector Electronics-I

2. Group members Rija Fatima Rajaas Tahir

3. Smoke detector A mechanical device that is sensitive to smoke or particular material in the air that transmits a signal to the measuring instrument. Smoke detector consists of two parts: A sensor to sense the smoke . Electronic horn to horn the people

4. Types Of Smoke Detector Photoelectric smoke Detector Ionization Smoke Detector

5. Photo Electric Smoke Detector The photoelectric type detector utilizes light as a detection mechanism There are two types of photoelectric smoke detectors Light sensing(scattering) Light obscuring(blocking)

6. Light Scattering Smoke detector Light scattering smoke detector depend on the ability of small airborne particles to scatter light. Scattering is due to the absorption, reflection, refraction, polarization, and diffraction.

7. The light emitted from the light source is not detected by the photo sensor. When smoke particles enter in the chamber increases, more light is scattered toward the sensor. When the concentration of particles reach the threshold , an alarm sound is produced.

8. Light obscuring smoke detector A projected beam can use a single light source to and photo sensor to detect a very large area Most such detectors use IR-LED or laser diode as a sensor. Detection of smoke by attenuated light. Uses a separate emitter and detector.

9. Ionization Smoke detector Have ionization chamber inside the detector. Ionization is very simple two plate chamber with voltage across along them along with the radioactive source of ionization.

10. Photoelectric circuit Implemented by us

11. internal Circuit

12. System hardware R1-300 ohms LED-white or any high  intensity LED LDR R3-100k potentiometer R2-10 kilo-ohms Q1-2N222,cs9013, or  similar NPN transistor R4-1.2 kilo-ohms R5-1.2 kilo-ohms Q2-cs9012, any general purpose PNP transistor C2-10nF

13. c3-2.2uF electrolytic capacitor R6-1.2 kilo-ohms R7-5 kilo-ohms C1-100nF 555 IC 9V battery or DC supply speaker (8-ohms )

14. Circuit Operation

15. The LED will light up the light dependent resistor (LDR ) and making its resistance very low (as low as 500 ohms). In this case,  transistor Q1 and Q2 are off. When there is smoke in the area, light from LED will be blocked resulting to an increase in LDR resistance. In this case, both transistor are on, and 555 timer starts to generate sound to the speaker.

16. Why Smoke Detector ? The circuit that is installed in the detector is upto the standards of the electronics-I All learning techniques were implemented in the circuit. Polished our abilities.