“An annoying little thing, really
Here’s a tiny pcb that you can stash somewhere and annoy people. Where’s that chirping coming from?
It uses an LED, piezo buzzer, ATTINY13 Atmel microcontroller, a very small amount of Arduino code, and a coin cell battery that should last about a week.
Battery life could be improved, with longer sleep times.
The device has but one function: sleep, then wake up periodically and blink and chirp, then go back to sleep.”