SMS based Fire Alarm System

Discussion in 'The Projects Forum' started by lordrey, Aug 4, 2013.

  1. lordrey

    Thread Starter New Member

    Aug 4, 2013
    Problem of connecting smoke detector to pc using parallel port? We are making a thesis work and we are having a problem about this. Its when the smoke detector detects smoke it should send data to pc, and then the pc will automatically send message to cellular phone. The question is how will i connect the smoke detector to the pc using parallel port. I have a smoke detector with a battery 9v. How will i control the voltage which is coming directly to my pc so my motherboard wont ruined. Anybody who knows the schematic way? I don't know alot in electronics.
  2. strantor

    AAC Fanatic!

    Oct 3, 2010
    Nobody with any sense of responsibility is going to advise you how to tamper with a smoke detector. If you want an indication when the detector alarms, I recommend placing a voice coil near it or some other means of detecting sound, with a set threshold to not trigger over a child's tantrum or domestic dispute.
    #12 likes this.
  3. Wendy


    Mar 24, 2008
    I see no problem with this project, as there is a pretty good likely hood that this is not the primary alarm system. Many people get by without any smoke detector, though this is considerably more risky.

    However, as a project for a complete novice I suspect you have bitten off more than you can chew.

    Bill Bowden's website can give you some basics, I suspect you are going to have to find someone technical to give a hand (and I'm not talking advice, I mean a real hand).
  4. Sensacell


    Jun 19, 2012
    A direct electrical connection would provide the easiest and most reliable interface.

    I would think that you could just use an NPN transistor hooked into the beeper circuit to create an open-collector interface. If the beeper has a self contained oscillator it would be simple to detect the level change on the beeper terminals, if it's a transducer alone, a simple capacitively coupled charge pump could trigger the transistor when AC was present on the transducer.
  5. doovalacky

    New Member

    Jul 18, 2013
    Nearly all 12v security alarm smoke detectors have a contact for external alarm. When we want to send them out via SMS/pager its input into the PC as a rs232 text stream from the control board and software looks at that port. A picaxe would probably let you do it.