As an instrument, it's basically a mash-up of an answering machine and a megaphone. It ends up being a small package with a loud punch, so you could use it to play the same sample over and over (and over...). It uses a solid-state recorder with a 120 second capacity (Winbond's ISD25120)
The really cool potential that I didn't explore in this project is the ability to control the recorder via a microcontroller. It looks like the recorder's memory is addressable via a 10-bit address setting. With that, you could have the resulting playback be driven by any number of environmental stimuli. I was looking at using an Amtel ATiny13 to drive it, because I only really needed a 4-bit address space, leaving 4 ADC lines for input. But, that's all to come still.
Step 1: The Design
The chip is a Winbond ISD 25120p. It records up to 120 seconds of audio at a 4KHz sample rate. It's about the quality of an answering machine (surprise!), but coupled with the amp in the megaphone, it produces a very textured sound.
The design here is the reference design shown on page 33 of the chip's datasheet The only things I really added were a couple of status LED and a 7805 voltage regulator. I drive it off a 9v battery, but you might get longer life out of 4-6 AA cells. YMMV.
The capacitors and resistors above the chip are filters for the mic and speaker, as well as a gain-preset.
I soldered this design together, more as an excuse to practice using a new soldering iron. If you plan on making more than 2 of these things, plan on etching a board. This is a very simple design, and you could probably make a single-sided board. If anyone wants to design one, I'll post it here for you....