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Using a relay or maybe a timer?

Discussion in 'Electronic Basics' started by eidsvikDM, Sep 19, 2003.

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  1. eidsvikDM

    eidsvikDM Guest

    This will be in regards to an automotive electrical system.

    I have gotten a hold of a really loud siren/buzzer from a car alarm. I
    have an alarm on my car now. It's reliability is waining but I still
    turn it on at night. Until I can afford a new alarm and install I
    wish to wire something to work in it's place. So I have simply wired
    this buzzer to my dome light and to a toggle switch in my trunk. I
    make sure the light is on, close my door, go to the trunk and flip the
    switch. Door opens and siren goes off that is until the door closes
    or dome light is switched off. Hey I thought it was a great idea at
    the time!

    I want this siren to go off for no less than a minute or indefinetly
    until I turn it off by a power switch (preferred). This will just be
    used in my driveway at night time.

    I have a family and cannot afford to replace this audio equipment in
    my car without dipping in to our monthly budget. I have some
    electrical knowledge and have installed my car stereo system from
    headunit to amplifiers and line drivers, etc. So some electrical
    basics I understand. Some help would be appreciated on how to wire
    this.

    Thanks
     
  2. Byron A Jeff

    Byron A Jeff Guest

    -This will be in regards to an automotive electrical system.
    -
    -I have gotten a hold of a really loud siren/buzzer from a car alarm. I
    -have an alarm on my car now. It's reliability is waining but I still
    -turn it on at night. Until I can afford a new alarm and install I
    -wish to wire something to work in it's place. So I have simply wired
    -this buzzer to my dome light and to a toggle switch in my trunk. I
    -make sure the light is on, close my door, go to the trunk and flip the
    -switch. Door opens and siren goes off that is until the door closes
    -or dome light is switched off. Hey I thought it was a great idea at
    -the time!

    It is a good idea.

    -
    -I want this siren to go off for no less than a minute or indefinetly
    -until I turn it off by a power switch (preferred). This will just be
    -used in my driveway at night time.

    OK.

    -
    -I have a family and cannot afford to replace this audio equipment in
    -my car without dipping in to our monthly budget. I have some
    -electrical knowledge and have installed my car stereo system from
    -headunit to amplifiers and line drivers, etc. So some electrical
    -basics I understand. Some help would be appreciated on how to wire
    -this.

    The classic solution to this would be a 555 timer wired as a one shot.
    A quick Google found this page with explanation and circuit:

    http://www.eleinmec.com/article.asp?4

    It talks about getting the timing and the circuit. You can use the output of
    the 555 to drive a relay that then powers the siren.

    Another suggestion if you really want to step up your electronics ability is
    to start looking at microcontroller such as a microchip PIC. The parts less
    than $3 USD in single quantities (check out http://www.glitchbuster.com for
    some sample prices) and they make great jellybeans for electronics projects.
    By this I mean that you learn how to use them once, then you can fit them
    into a multitude of projects. For example a single 12F628 for $1.28 with a
    bit of JAL or XCSB code can do everything the 555 circuit does. You can find
    everything PIC a http://www.piclist.com

    Hope this gives you some insight.

    BAJ
     
  3. John Fields

    John Fields Guest

    ---


    VEHICLE +12>----------------O
    |COM
    DOME LIGHT+12>----+---O---> |
    | |NO
    COIL +--------BUZZER+ >
    |
    | <---O----+
    |TRUNK SWITCH
    O
    |
    GND>---+-----------------------BUZZER- >

    When you leave your vehicle you turn on the dome light and then turn on
    the trunk switch just like you do now.

    If anyone opens a door, +12V from the dome light goes into the relay
    coil and closes the COM and NC contacts. When this happens +12 is sent
    to the buzzer and also to the relay coil, latching it, so that if the
    door is closed and the 12V from the dome light turned off, the relay
    will still stay made because of the 12V going to the coil through the
    closed contacts until the trunk switch is turned off.
     
  4. Hey this is exactly what I needed. Thanks for your time starting me off.
    OK off to do some tinkering

    Jason
     
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