Project 11 is very simple to wire up... and the program is one of the shortest we've seen so far. It uses a sine wave, again, to generate values that fluctuate, allowing the piezo buzzer to warble like an alarm.
I've got the sound from the unedited program playing in the first video. It's loud... and obnoxious. This would definitely annoy a brother or sister who entered your room without permission! I modified the variable value to start with a base of 1000 (instead of 2000) and the alarm has a lower tone... but still loud.
I'm amazed at the volume generated from this tiny device - it was the smallest one in the bins at Radio Shack. I'm sure the larger ones require more voltage, but little fella is rated for between 3 and 20 volts. I'm glad I'm not hitting it with 20 volts!