I am trying to design a circuit that will have a mic that triggers an mp3 player to play a message when it detects a sound.

There are some really cheap mp3 players now and I was thinking I could connect a mic to a potentiometer to give it some adjustability and then have it control the play button of the mp3 player with a transistor. As you can tell I'm a real beginner in electronics and I'm not sure if this is even possible. Would it just keep the play button on or is there a way to make this a "momentary" circuit like the play button on the mp3?

Also, can I connect the output of the mp3 player (speaker) back to the mic circuit so that it will prevent the mic from triggering again while the mp3 is playing? I imagine a transistor with an inverter so that while there is current to the speaker it keeps the mic circuit open. I think a 555 timer would do it but the disadvantage is that it would not automatically change the duration of blocking the mic with different mp3 durations.

I hope some of this makes sense. I'm still learning.

 

A while ago, I bought a few 16 meg mp3 players, surplus store. I've got a simple circuit some place for making one play when power is applied, just a transistor, capacitor, and a resistor. Will post it if I find it, been a while. Never got around to finishing that project. Basically wanted to have it play a song after the sun went down, all solar powered. Needed a bigger amplifier, more battery power, and no idea how to turn it off after the song was done (would continously loop).

 

a schmitt trigger set up with a time delay of say 5 to 10secs, using discrete parts could do it for you

moz

 

Try an internet search using the terms "sound activated switch." You should find at leas half a dozen schematics if you dig long enough. Pick one or two that you think you could handle making, and we'll go from there.

 

Moz,
Thanks that is exactly what I was looking for. Here's a link that helps explains it if anyone else is interested.
http://www.play-hookey.com/digital/experiments/rtl_schmitt.html

Looks like even I may be able to build this one.