fire detection system

Discussion in 'General Electronics Chat' started by ayodele234, Jan 5, 2013.

  1. ayodele234

    Thread Starter New Member

    Apr 26, 2011
    Good day friends, i have been working on fire detection system as a project but there are lots of things i don't understand how:
    1. the connection of the sensors i.e smoke detector, heat detector and manual call point.
    2. The circuit the sense and trigger the alarm system.
    Pls the connection diagram of the sensors is attached. Pls i will appreciate anyboby who have any knowledge on the circuit i can use and who can give detailed explanation on the working principle of the fire detection system.
    Last edited by a moderator: Jan 6, 2013
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    Fire alarms work on two systems, Analogue or Digital

    Analogue use a 24 volt supply to the detectors which are all wired in parallel. There is an "end of line resistor/sensor" or EOL across the supply at the last sensor, this is so when a device is removed or a break in the cable the panel senses the voltage increase and goes into Fault mode.

    Each device has a 470 ohms resistor inside and when a fire condition is met the device shunts the resistor directly across the supply and the voltage drops and the panel goes into Fire mode, the manual call points are just a micro switch and a 470 ohms resistor.
  3. ayodele234

    Thread Starter New Member

    Apr 26, 2011
    Thanks you to Mr. Dodgydave, please help me on the electronic circuit diagram (both digital and analogue).
    An example of the circuit is attached.