• Register
  • Login
  • Search 4 million + Products
    this message might be for you!

    This home smoke detector circuit warns the user against fire accidents.
    It relies on the smoke that is produced in the event of a fire and passes between a bulb and an LDR, the amount of light falling on the LDR decreases. This type of circuit is called optical smoke detector. Do not use it as a home smoke detector it’s jus for electronic projects.

    This causes the resistance of LDR to increase and the voltage at the base of the transistor is pulled high due to which the supply to the COB (chip-on-board) is completed. The sensitivity of the smoke detector depends on the distance between bulb and LDR as well as setting of preset VR1. Thus by placing the bulb and the LDR at appropriate distances, one may vary preset VR1 to get optimum sensitivity.
    We have not build this smoke alarm detector.

    Smoke Detector Circuit Schematic

    smoke detector circuit

    For smoke detector installation and maintenance use a near electrician.

    How to Install a Smoke Detector

    Other smoke detectors circuits

    please send us an email if you know other interesting circuits

    RE46C190 photoelectric smoke detectorsource
    Using this photoelectric smoke detector circuit can be designed a very simple and low power smoke detector alarm project that is based on the RE46C190 smoke detector IC . With minimal external components, this smoke detectors alarm circuit will provide all the required features for a photoelectric smoke detector type electronic project.

    The design incorporates a gain-selectable photo amplifier for use with an infrared emitter detector pair. An internal oscillator strobes power to the smoke detection circuitry every 10 seconds, to keep the standby current to a minimum. If smoke is sensed, the detection rate is increased to verify an Alarm condition.

    RE46C190 smoke detector photoelectric circuit

    Smoke detector with gas sensor TGS 813source

    The simple schematic diagram of a smoke detector presented here utilizes the gas sensor TGS 813 as the main detecting component. The circuit is pretty easy to build and performs useful fire hazard detection once installed into a possible fire prone zone.
    IC1 = 741
    IC2 = 7805
    T1 = TIP122

    gas sensor TGS813 smoke detector

    Buy assembled smoke detectors

    Honeywell 5808W3 Wireless Smoke/Heat Detector
    Wireless photoelectronic smoke / heat / freeze detector
    Intended for use with Honeywell wireless burglar alarm
    best price $69
    2WTAB 2-Wire Photoelectric Smoke Detector with Thermal S
    85 dB sounder. In-line terminals
    Isolated thermal sensor
    best price $44
    Kidde Plc Ac Smoke/Co Alarm – best price $59
    smoke and carbon monoxide alarm.
    Power Source: 120VAC, 9V battery backup
    Smoke Sensor: Photoelectric
    CO Sensor: Electrochemical
    Audio Alarm: 85dB at 10ft

    ask a question

    68 Responses to "Smoke Detector Circuit"

    1. what it’s the model or the number of this COB?

    2. what is COB(chip on board) in this circuit.
      what it’s model or number of this COB?

    3. COB( Circuit On Board) is a miniature button shaped device containg all the circuit parts in one chip.COB used in the circuit is a melody generating ROM chip with oscillator. It has pins for positive, negative connections and an output pin. You can use any type COB that generates music or siren tones
      D.Mohan kumar

    4. i want to now pin discription of the givne digram of smoke detector

    5. you may search http://www.alldatasheet.com to get the data sheet with pin assignment of B548(BC148) and TDA 2002.The same data sheets are also available in the postings of electroschematics.Search giving BC548 and TDA2002 circuits. Chip On Board (COB) is a ready made one.Its pins are marked in the PCB of the chip

      • i need the complete information regarding to detector with sensor tgs 813

        resistors values?
        capacitors values??

        Please help me!

      • pls sir i have problem with the COB. i submitted the topic as my project to be defended on the 23rd of this month. pls sir how do i go about it. i would appreciate any information. +2348136470514

      • sir,chip on board &circuit on board are same or not

    6. kindly tell me model number of the COB

    7. which COB required for this circuit??

    8. What number of COB required??

    9. Can ì use any alarm circiut apart from the COB sound generator ?

    10. i want to know the purpose of TDA2002 USE IN PHOTOELECTRIC SMOKE DETECTOR

    11. fakorede michael.o says: on October 22, 2010 at 6:02 pm

      what is the number of cob required for the fire alarm circuit with TDA 2002

    12. fakorede michael.o says: on October 22, 2010 at 6:42 pm

      What is the number of COB[chip on board] required for the fire alarm circuit with TDA 2002 my Email OLAYEMI.MICHAEL@yahoo.com

    13. i really want to know the usefulness of the COB and what is the work of the tda2002 ic

    14. what is the model number of the COB (chip on board)

    15. what is the range(or) rating of ldr in a smoke detector cicuit.plz give me re[ly its very important to me.

    16. hello sir ,
      sir i connected this circuit i have small doubt about this . when i given supply to the circuit the light glows and at the same time alarm sound also coming. when i closed the LDR with darkness the sound gets off. here my doubt is the ckt based on light only but we call it as smoke detector…please clarify …

    17. please mail me it’s working procedure…if possible…

    18. what is the function of the COB or CHIP ON BOARD?

    19. we provide the rate flowing

      Photoelectric Electronic Smoke detector, Model 2151, Make System Sensor
      Base of Photo Electronic Smoke Detector, Model 2151, Make System Sensor
      Out Door Call Point (Break Glass) KAC Alarm Co. Ltd. Model KSR1

      Horn Strobe Light, Make Wheelock, MT Series, Model MT-24-WM, 24VDC 20-120 Flashes/Min, 75DB
      Cable 4 x 1.5 mm2, Flame Retardant Halogen free Double insulated cable 75 ohm/Km, BS 6387, For Smoke Detector
      Cable 2 x 4.0 mm2, Flame Retardant Halogen free Double insulated cable BS 6387, For Bell & Strobe Light
      Weather proof Junction Box 200x200x100 mm with terminal & Glands

      Please sand the rate as soon as pose val



    20. how could i impilment this circuit into a burgular alarm circut

    21. i want to know the purpose of ic2 TDA2002. PLEASE REPLY

    22. i m DAE student. i want to learn electornic ciruit .

    23. what is the working purpose of TDA 2002,COB(Chip on board) and vr1,vr2 in smoking alarm detector.

    24. wat is the best way to build a smoke detector circuit?

    25. pls can u tell me the best way to build a smoke alarm circuit?

    26. please tell me how to make simple smoke detector

    27. what is the meaning of COB?

    28. please give proper number of chip (eg cob = 12250)

    29. please give proper number of chip

    30. please provide figure of cob and number too as fast as possible

    31. LAL JANI BASHA says: on July 5, 2011 at 7:55 pm

      how much voltage i have to give to smoke dector with gas sensor TGS813 and how much money we have to invest for dat ………………………………….SIR

    32. Hellow.. What if I change smoke detector sensor TGS 813 into MQ-7 carbon monoxide detector, is that possible to make it a carbon monoxide detector????please help me I’m new to this…

    33. What if I change smoke detector sensor TGS 813 into MQ-7 carbon monoxide detector, is that possible to make it a carbon monoxide detector????please help me I’m new to this…can u guide me to this

    34. i am bachelor of electronics i wantt to learn electronics circuit analysis and making of circuit diagrame kindly teach electronics basics

    35. sandeep hyderabad says: on December 21, 2011 at 12:49 pm

      Sir please send me a compleate project report on smoke sensor detector. With programing and compleate block diagram and circuit diagram.
      on this email id – sandeep1embedded@gmail.com


    37. Vaibhav bhutada says: on January 30, 2012 at 7:49 pm

      I want to design a 8051 based fire alarm system in which i would use, smoke detector as input sensor and hooter and sprinklers will be the output devices. LCD interfacing for display.
      Please help me to design the circuit diagram for it. send me 8051 based design.

      Thank you.

    38. send me more circuit

    39. BANDO +BIA =CHUA

    40. sir,circuit on board and chip on board are same or not please reply to me now i’m eager to waiting for your guiding

    41. sir can i have the block diagram of this circiut?? RE46C190 photoelectric smoke detector… thank you! =)

    42. sir wich type of cob we will use??

    43. RAMBABU,GAVARA says: on March 21, 2012 at 4:05 am

      request COB number and function

    44. Bayan Moh. Abu-Tama says: on March 21, 2012 at 4:29 pm

      excuse me , can I use DAQ in this circuit and enter the output on a spacial program on computer .

    45. himanshu bahuguna says: on March 22, 2012 at 4:14 pm

      sir how can we test and use this circuit.

    46. Pls sir tell me about d cob and d Ic2tda2002. Am working on d project. Thank u sir.

    47. Hi dear
      I want to produce good smoke detector at Iran.who would like help me and guide me in this way?I thanks every one who send me high quality smoke detector circuit schematic.
      your sincerely
      Behnam Ostad Abbaslou
      FaceBook:Behnam Ostad Abbaslou

    48. raphael ignatius says: on May 25, 2012 at 9:53 pm

      please i need the wiring diagram of the detectors and panels, including the alarm. i want to know how it is been connected, all types.

    49. raphael ignatius says: on May 25, 2012 at 10:00 pm

      i nee the wiring diagram of the detectors and alarm including panels

    50. pls
      show me the pin diagram of COB and no of cob used in above cct smoke detector

    51. what il COB

    52. what is cob

    53. sir plz give me the cicuit diagram of simplest project of smoke alarm student level.thanks…..

    54. pls give me link others like this projects.

    55. i want to know the purpose of ic2 TDA2002. PLEASE REPLY

    56. Guys ….. I want to make a circuit which emits smoke cloud plz help me . Or Is it possible ….?

    57. renu adhikari says: on April 9, 2015 at 5:09 pm

      sir pllzzz give me synopsis of this project like as introduction , equpment used , working and approximate cost in make this alarm

    58. Sir how to install the smoke detector in fire panel

    59. What is COB?how to i make COB?

    You need to log in if you need to post comments on ElectroSchematics.com or register if you do not have an account.