Sound detected countdown timer

[Aranka]

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,

[GANEEV SINGH]

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

[Ashutosh Bhatt]

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

[Author]

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