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Sound Detector Help

Discussion in 'General Electronics Discussion' started by westy29, Jul 24, 2011.

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  1. westy29


    Jul 24, 2011
    Hey guys

    I'm new to the forum and this is my first post. I'm hoping somebody has the knowledge to help me create or find a device.

    I need a device that can detect sound and light up via a light once a certain sound level
    Is exceeded. Basically my brother is up at late hours often chatting on his pc with a headset on. He can easily get carried away and become too loud which usually wakes others up. If I tell him to be quiet he will, he just doesn't have the common sense to maintain this.

    So basically I want to have something to sit at his desk that will illuminate when he gets too loud. I figured a bright led light in his face will remind him.

    My friend has a small neon light setup that does exactly this in his car. It can be turned up and down to various sound levels. The only problem is that it works on a cigarette lighter power.

    Would modding an existing product like above be possible? Or could something else be purchased or created?

    Thanks in advance for the help!

  2. westy29


    Jul 24, 2011
    Yeah that's pretty much what I need. Only problem is I'm in Australia so I need to find one that will work here.
  3. TBennettcc


    Dec 4, 2010
  4. awright


    Oct 10, 2009
    If your friend's item would do your job and it works off a 12 volt automobile cigarette lighter you should have no difficulty whatsoever finding a mains-powered 12 volt "wall wart" power supply to power the device. Just be careful of polarity and be sure the power supply can provide enough current. A regulated supply is best, but any with the right voltage and current rating would probably work.

    If your friend's device is a commercial product it might have it's current requirement on the label. If not, use a multimeter to measure the current pulled by your friend's device and find a 12 volt power supply with a current rating anything more than about 110% of what his device pulls. Measure it in passive and active mode (that is, while in the alarm state).

    Around here (California), used and discarded power modules are a dime a dozen in all common electronics equipment voltage and current ratings and 12 volts at an amp or more is a common rating.

    If you wanted to make a construction project out of it you could construct a sound level alarm with an electret mike, an op-amp, and a few electronic components. You do have to do some filtering of the signal because such things as air conditioners or passing cars can produce high levels of low frequency sound that you may not perceive (due to the frequency characteristics of the ear) but which might trigger an unfiltered unit.

    If you are not into do-it-yourself circuit construction, there are probably sound level detector kits out there for a modest price. Try Velleman, Jaycar, or google "electronic kits." They are easy and fun to build and you usually learn how the devices work.

  5. westy29


    Jul 24, 2011
    Awesome, Im gonna check out my local store tomorrow and see what they have on offer. Thanks for all the help!
  6. davenn

    davenn Moderator

    Sep 5, 2009
    sounds like you need one of my calibrated sound monitors ;) accurate to +- 1 dB from 60 to 130db. Actually prob out of your price range. These units get installed in clubs/pubs etc to monitor the sound level of the band/disco etc and has visible displays plus relay output for switching off power to the sound sys till they wind the level down.
    Council noise level requirements blah blah

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