Little Alice

This unassuming little module is he WTV020M01. It provides a cheap and reliable way of playing audio using nothing more than an 8-bit microcontroller. (yes, it is possible to – and I have in the past – create an audio player from a microcontroller yourself, but playing 8-bit audio at 22khz requires a lot of processing cycles which wouldn’t leave much time to do all the other cool stuff, like lighting up the eyes and controlling the servo etc.)

Simply put, you create your audio in a special format (.ad4 which is little more than a “headerless” WAV audio file) copy it onto a freshly formatted sd card, then send a command to the module to tell it the number of the file you wish to play (the files are named 0000.ad4, 0001.ad4, 0002.ad4 etc)

Alice Cooper’s “Wind Up Toy” just felt like the perfect soundtrack for this little vignette. Not only is it a great song (featuring no less than Joe Satriani on guitar) but the lyrics fit beautifully with this scene.

There’s also a great little spoken line towards the end of the song, which I thought would make a great finish for the “laser lights” pay-off.

I hot-glued a 2″ speaker (a full speaker with a magnet and paper cone, not just a crappy piezo buzzer) onto a piece of mdf with a large hole laser-cut into it (so the sound could escape from the bottom of the diorama base) and connected it up to the WTV020M01 module.

I glued the side onto the base, with a small 6mm tactile push button (hot)glued onto a hole in the side.

As space inside the base was a little cramped (and I didn’t want to inadvertently press anything up against either the servo or the rod that it turn, causing it to stop working) I decided against adding a battery and charge circuit inside the base.

The entire thing is powered directly from a usb-micro socket on the rear of the base. Any standard micro-usb phone charger can be used to provide power.