Mike D. @ ITP

When I was making the crickets, I ran into a lot of issues with finding a reasonably-priced, pcomp-able sound generation system. There’s some work (especially by Limor Fried) into making open-source MP3 players, but they ain’t cheap and they take a lot of tinkering. There’s voice chips, like those found in toys and/or sold at Radio Shack, but they didn’t have nearly enough storage or fidelity for my uses. And then there’s cheap, crappy MP3 players — and that’s where I found the best luck.

I’ve done some writeups of how I made the Concrete Cricket design (there’s a bit about that here and here), but I’ve been asked about gutting the MP3 players, so here’s that! It’s stupid-simple — you just wire up two sides of the Play button, run wires to either side of a reed relay, and control the relay through an Arduino. I know some people (notably Michael Chladil) have also soldered wires to the indicator LED and watched when it went low or high through an analog read, but I’m not nearly that fancy. I was hoping to have a nearly idiot-proof, mostly self-running system, and this works well for that.

The story, in pictures, follows.

MP3 shell:

After taking the guts out:

Wiring up the switch:

After that, I wired up connections to the audio out and battery in (though you could just as easily keep things the way they came):

Reed relay (the 250 ohm, 5v variety from your local friendly Radio Shack) in use:

Using an Arduino and the aforementioned relay to turn MP3 player on and off:

On a breadboard:

Perfboard everything all nice:

And everything all wired up nicely (and all wires covered in heat shrink):

Oh, and because I’ve been asked about this as well, a stupid-simple LM386 Op-Amp circuit to go along with this:

It’s painfully cheap on Electronic Goldmine, but you can find ‘em at Radio Shack if you’re in a bind.