1. The ability to beep at random intervals
2. Minimal parts needed (simplicity/elegance of design)
3. I wanted to use a microcontroller (because I recently started the journey of learning about microcontrollers)
This project was inspired by an article in MAKE magazine about making a similar device with a 555 timer chip.
After making my prototype, I searched instructables.com and found the Raven, which is a similar beeping thing using a microcontroller. I decided to add my instructable because it uses less parts and has random intervals.
Step 1: Parts Required
- ATtiny13 microcontroller (Sparkfun.com)
- AA batteries (3)
- Battery Holder with switch (Digikey part # SBH-331AS-ND)
- 8-pin socket for microcontroller
- Speaker (small 8 Ohm or piezoelectric buzzer)
- Silicon adhesive (RTV)
I made this entire project from parts I had in the house. You can use almost any battery(s) that has a voltage within the microcontroller's range (1.8-5.5 Volts for the ATtiny13). The higher the voltage, the louder the beep.
Almost any small speaker will work. You may want to experiment with different small speakers. I chose the speaker with the plastic membrane because it didn't make a click noise at the end of the beep like some other small speakers.
You can adapt the source code for other microcontrollers. It would potentially only require a change to the timer register settings.