security system

Discussion in 'The Projects Forum' started by lihle, Jan 25, 2010.

  1. lihle

    Thread Starter Active Member

    Apr 12, 2009
    83
    3
    I am trying to design a home based security system that would use sensors.in case of break in ,the system activates an alarm system and an sms is sent to the owner of the house.
    i need more information about the mobile interface with the pic, because the message would be sent via a mobile phone.And how to connect sensors to a microcontroller.
     
  2. jeka616

    Active Member

    Jan 14, 2009
    121
    1
    hi
    Use PIR sensors as required, and 2 simple timer relays ( 2 transistor per relay, solid design...). 1 - is to delay the activation, so you can leave the house (I don't recommend outside activation, as this can be de-activated from outside obviously). 2 - is to shut off the alarm , as you don't want the siren to last for ages, 20-30 mins is more than enough to scare invaders.

    As you will be using mobile phone, just have your number (and record house mobile on your own phone as "security alarm" or so?) on redial, and connect one of the outputs of alarm activation relay to mobile phones "YES" button. It will call automatically when PIR detects.

    Make sure you use UPS. Just a hint, you may want to add 15-20W light bulb paralel at UPS output, as the security system will not use much power in "waiting" conditions, and the UPS will shut off, as it is designed to save power.

    Let me know if any particular drawings needed, I'll try to sketch something. I've equipped my friends garage with such a system.

    This is easy to build, very cheap if you are not going to play with microcontrollers etc.
     
  3. lihle

    Thread Starter Active Member

    Apr 12, 2009
    83
    3
    jeka616

    thanks man.but i will need drawings and also i want to control it remotely.

    lihle
     
  4. jeka616

    Active Member

    Jan 14, 2009
    121
    1
    I'll get it for you tomorrow. It is in my EDD, at home..
     
  5. lihle

    Thread Starter Active Member

    Apr 12, 2009
    83
    3
    hope to get it on time

    lihle
     
  6. jeka616

    Active Member

    Jan 14, 2009
    121
    1
    Ok, here we go.

    I've attached 3 timer circuits, I have used #3 a lot. Very reliable. You will need to make 2 of them. Play with the timer components, to get the time you want.

    1 - to shut off the alarm after whatever minutes you want the siren go on.
    2nd - to disable alarm for 2-3 mins, so one can leave the house. The siren will go on 1st relay, an in series with this, will go the second relay.

    As you turn on the power while leaving, you will need push button on 2nd relay. The PIR sensors will activate anyways, as they will detect you going out. But the siren will be off as the delay relay isolated the circuit to siren (so is the mobile phone trigger) for 2-3 mins.

    After you leave, the PIR will reset, in 40-50 seconds (depending on model, anyways you have 2-3mins sufficient). The delay timer will de-activate, and the siren will be hooked into 1st alarm. And the system will go on "watch" mode.

    The PIR is ready module, costs ~ 20$ some. it has 4 outputs: +/- 12 V power, and 2 relay outputs. You can chose the "normally closed" or "normally open" position. I've used normally open position, so the alarm activates when the PIR detecs, and relay goes to "close". Remember, you will need stabilized power supply for PIR, so use LM7812. Don't put siren on the same power unit, as when going-off, it can draw > 1.5amps (depending on type, mine did..).

    Connect the PIR output relays to relay#1 activation button.

    Hope you can hook together 2 relays as I described. Let me know if you have questions.

    Good luck
     
  7. lihle

    Thread Starter Active Member

    Apr 12, 2009
    83
    3
    thanks man hope it will work as you have explain
     
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