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You are here: Home / Topics / Sound detected countdown timer

Sound detected countdown timer

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Electronics › Electronics › Sound detected countdown timer

  • This topic has 2 replies, 3 voices, and was last updated 8 years, 4 months ago by Ashutosh Bhatt.
Viewing 3 posts - 1 through 3 (of 3 total)
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    Posts
  • February 7, 2011 at 8:10 am #662
    Aranka
    Participant

    Hi guys, I’m trying to create a project that when activated by a sound, starts a countdown and then sounds an alarm (about 5 mins – pulsating one using a 555 timer) and can repeat.

    Or, if the time delay can decrease (between each alarm) after each run. Ie –

    Sound detected, Countdown starts, Alarm sounds, (back to countdown start, if possible ‘take 1 min’ )

    Thanks so much for any help!! I’m so confused lol, I’ve realy got no idea about values etc. So I’d be SO grateful for any help!! All the best,

    January 17, 2017 at 7:29 am #14341
    GANEEV SINGH
    Participant

    Hi Aranka

    Here's how your project is going to be:

    A sensor, maybe a condenser mic, will sense the sound and then pass its signal to a comparator like LM358. A threshold will be set ot this comparator which will decide when to trigger the 555 timer circuit. 555 will work in monostable mode and its output will be connected to a circuit which will operate the alarm.

    The desired delay is calculated according to the formula: 1.1xRxC seconds.

    Hope this helps :)

    January 17, 2017 at 6:07 pm #14343
    Ashutosh Bhatt
    Participant

    do you want to display counting on 7 segment display? u can use CD4026 for this purpose

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