Advice needed on reverse alarm

Discussion in 'The Projects Forum' started by 0Hz, Jan 11, 2013.

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  1. 0Hz

    Thread Starter New Member

    Sep 4, 2012
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    Sorry if this is a stupid question, but I'm pretty new to electronics.

    I have a 90db piezo buzzer that I wanted to use to make "quick & dirty" reverse, or backup alarm for my dad's truck. My first idea was to just use a thermal turn signal flasher in series with the buzzer, but that doesn't work. I assume that it is because of the fact that the buzzer only draws ≈20mA and that this is not enough to trigger the flasher, because the buzzer is just on continuously when the truck is in reverse. But I could be wrong about that...

    Anyways, is there any thing that I can add to to load on the flasher that will draw more current safely and cause it to start turning on and off? Thanks for the insight.
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    I think you got the wrong buzzer. There are pulsating buzzers that do that when 12V continuous is applied.
     
  3. 0Hz

    Thread Starter New Member

    Sep 4, 2012
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    That's what I thought too, and this is one of those "Pulsing" buzzers, but the "pulse" mode is so fast that it's really just like a different pitch.
     
  4. tubeguy

    Well-Known Member

    Nov 3, 2012
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    Why not just wire in an automotive turn signal lamp ?
    (or two if one blinks too fast)
     
  5. 0Hz

    Thread Starter New Member

    Sep 4, 2012
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    That's a good idea. I ended up realizing that I had enough parts to make a circuit using a 555 timer instead. Thanks for the advice though. In case anyone wants to know, I found that when driving a piezo from a 555 in astable mode, to make a very clean "on, off" sound rather than a sort of modulated pulse (never fully off), make sure to sink the current for the piezo (i.e. connect the negative terminal of the buzzer to the output pin of the 555).
     
  6. Georacer

    Moderator

    Nov 25, 2009
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