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Time Delay Relay for caralarm-->gpstracker

Discussion in 'General Electronics Discussion' started by fuzzyduck, Aug 20, 2013.

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  1. fuzzyduck

    fuzzyduck

    4
    0
    Aug 20, 2013
    Hi,

    im newbe and noob, just registered.

    I want to hook up my car alarm to my gps tracker so i receive a sms on my Phone when the alarm sounds.

    I need to use the siren trigger cable connected to the aux-input port on my tracker.

    The siren triggercable gives a quick pulse to the siren when i activate or deactivate the alarm making the siren goes 'whoop' once when activated. and 'whoop whoop' when deactivated. Thats one pulse an two pulses over the triggercable.

    Tried and tested, now, whenever i activate alarm and the siren goes whoop once i get a sms on my Phone saying the tracker received an external input on portnumber #, so the basics work.

    But ofcouse i just want a sms when the actual siren alarms and not when im standing right beside it activating it. So i need some kind of time delayed relay with a triggerduration longer then the quick 'whoop'-sound pulses so it only activates the sms to my Phone when needed.

    Ive been looking at http://www.macromatic.com/blog/understanding-time-delay-relay-functions/ for my kind of relay but im not sure if its there.

    My car works at 24v and so does the alarm/tracker

    Can anyone help me? Im ready to solder if needed.

    thx in advance!
     
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,268
    Nov 28, 2011
    What are the electrical characteristics of the signal that you're sending from the alarm to the tracker? You say it sends a "pulse" but we need to know the electrical characteristics.

    Can you give the model numbers of the alarm and the tracker? Can you link to detailed information on them?
     
  3. fuzzyduck

    fuzzyduck

    4
    0
    Aug 20, 2013
    Hi Kris,

    Tracker
    Xexun XT-008
    http://www.gpstracker7.com/upfile/download/2013012215482108201.pdf

    I use the digital input port. It got 6 of those. That works when i tap into the signalwire of the siren.

    Alarm:
    The system is the Scorpion SA35:
    http://www.scorpionauto.com/scorpion7.htm

    Same as SA30 but then 24v instead of 12.

    No manual only in my hands but that doesnt give voltages over wires.

    The siren has 3 wires. Red Black and yellow. Red and black are 24v and mass. The yellow is the 'pulse'-giver. Dunno voltage though its all tucked away now atm. Lets presume 24v.

    I think i need a relay which skips short pulse but acts on a pulse longer then a split second.

    Im looking at http://www.macromatic.com/blog/understanding-time-delay-relay-functions/ but cant figure out which one. I think none.
     
  4. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,268
    Nov 28, 2011
    I think a simple resistor-capacitor delay will do what you want. I can't be sure because those documents don't give enough information on the output and input characteristcs, but it's worth a try.

    So you currently have a direct connection running from the siren control output of the alarm to the auxiliary input on the tracker, right? Cut that wire and insert a resistor across the break. And connect a capacitor with its positive wire to the tracker side of the resistor, and its negative wire to the 0V wire (or to chassis).

    For the capacitor, use a 470 uF (470 microfarad) electrolytic capacitor, rated at 35V. Other parameters are not important. Electrolytics are often available in two styles - the "radial" style, with two leads coming out of the same end, and "axial", with one lead out each end. Choose whichever is most convenient for mounting. Make sure you get polarity correct.

    For the resistor, try 2.2 kilohms (other parameters such as power and tolerance aren't important). Resistors are not polarised. If the delay isn't long enough, increase the resistor value. If the tracker doesn't activate at all when the alarm goes off, reduce the resistor value. You might want to buy several different values (resistors are only a few cents).

    Of course, make sure you insulate those components once you've finished, so they can't touch anything.

    Good luck!
     
  5. fuzzyduck

    fuzzyduck

    4
    0
    Aug 20, 2013
    Hi,

    Very many thx for your solution.

    Lemme rephrase your explanation in my own noob language ;)

    Im gonna tap into the yellow wire. so i have '2 yellow' signal cables.

    The original i leave intact because i dont want to mess with the original cable.

    The new made on is gonna connect to the gpstracker and i solder in a capacitor and a resistor.

    Let me get this straight in noobterms:
    The alarm goes af and a current flows down the cable to the siren through the resistor and capacitator. When the signal continues the capacitator is gonna charge and will intercept the current to the GPStracker? So when its full the current contignues down the line to the gpstracker?

    Am i right or just plain wrong :p
     
  6. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,268
    Nov 28, 2011
    Kind of. The resistor and capacitor together form a delay circuit. When the voltage from the alarm goes high (+24V), the capacitor starts to charge, through the resistor. The resistor limits the current. It's a bit like a rechargeable battery that charges up slowly because of the current flowing through the resistor.

    As the capacitor charges up, the voltage across the capacitor increases. This is the voltage that drives the auxiliary input on the tracker. At a certain voltage, the tracker will regard this voltage as high or active, and will generate an SMS.

    If the alarm generates just a short pulse, the capacitor won't have enough time to charge up to a voltage that the tracker regards as high, so it won't generate an SMS.

    This is all based on assumptions I've made about the characteristics of the alarm output and the tracker input. I can't say for sure that it will work, but it's worth a try.
     
  7. fuzzyduck

    fuzzyduck

    4
    0
    Aug 20, 2013
    thx for the explanation.

    I will go on holiday next week but ill try your solution after. Hope te post in about a month!
     
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