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smoke detector circuit

Discussion in 'General Electronics Discussion' started by ramy, Feb 2, 2014.

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  1. ramy

    ramy

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    Nov 4, 2013
    Hello every one,
    I need a smoke detector design that uses a 1KL3A smoke detector module, I tried some circuit designs but they don't work, please I need help
     
  2. davenn

    davenn Moderator

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    Sep 5, 2009
    show us the circuit designs you found
    some one here may see what is wrong with them ... or maybe it was your construction that failed ??

    Dave
     
  3. gorgon

    gorgon

    603
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    Jun 6, 2011
    To make a smoke detector, you'll need a mechanical design in addition to the Electronics. All smoke detectors I've seen use a dark Chamber, with a LED to light up any smoke particles present in the chamber. The Optical detector will then 'see' the dispersed light from this. The optical detector does not see the LED light itself.

    To make this chamber and to make the airflow through it consistent without ambient light, is the main problem designing a smoke detector.
     
  4. davenn

    davenn Moderator

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    Sep 5, 2009
    actually 99% of smoke detectors these days use a radioactive source

    lets wait and see of ramy responds with some links to circuits
     
    Last edited: Feb 3, 2014
  5. gorgon

    gorgon

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    Jun 6, 2011
    In the Company I work in, it's the other way around. Ionic detectors are very seldom in the professional market. It could of course be different in the consumer market, but the radioactive aspect of the ionic detector, in this environmental focused time, is not political correct :)
    The detector in question is an optical detector, but let's wait for an answer.
     
  6. ramy

    ramy

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    Nov 4, 2013
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    1) Try turning the LED around.

    2) do you understand why replacing one of those capacitors with a 0.1uF cap is fine but replacing the other will change the operation?

    3) What are you replacing the thermistor with -- exactly?

    4) What is your power supply?

    5) 6v seems on the low side for a 555. Have you verified the variant you have is specced for operation at 6v?
     
  8. ramy

    ramy

    7
    0
    Nov 4, 2013
    The LED is working when i put the i/p directly on it.
    I don't know exactly which one of the 2 capacitors will change the operation, I had to change them because I don't have 0.01 or 0.04 capacitors.
    I replaced the thermistor with a 1KL3A smoke detector module but the buzzer is working all the time not only when smoke is released
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,412
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    Jan 21, 2010
    What is your power supply?

    6v seems on the low side for a 555. Have you verified the variant you have is specced for operation at 6v? (edit, a standard 555 seems to be specified down to 4.5V, so 6V should be ok)

    What's "the i/p"?

    Have you tried turning it around? If it still doesn't light up then you may have the wrong value resistor, a wiring error, or a destroyed LED.

    I just hope "the i/p" isn't your power source.

    Random changes are not the sort of thing you should do. Replace the 0.04uF capacitor with two 0.1uF capacitors in series. That gives you 0.05uF which is a lot closer.

    Does the sound change?

    You can't just make random changes and expect things to work.

    Do you have any data on this smoke detector? It might be possible to make it work, but you may have to make other changes.

    also:
     
  10. gorgon

    gorgon

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    Jun 6, 2011
    What you did make is a light detector. Putting the Optical detector in Complete darkness will turn off the buzzer. If the LED is not working the voltage is either too low or the LED is reversed.
     
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