At the hotel where I work, we are having a problem with guests keeping luggage carts in their rooms overnight and keeping other guests from using them. What we want to do is have something (possibly using Arduino) that, after 15 minutes of leaving the front desk area, plays a sound until it returns to the front desk area. We would be mounting the pieces in a secure box underneath the luggage carts.
I know I would/could use an Adafruit Wave Shield to play the audio, but the timing and proximity is where I am stuck. Is this something that would be doable or would I be better off looking for a pre-built solution?
You should use an ATtiny85 . It has four digital outputs and two timers plus analog in a $2.00 8-pin ic. I don't know how to do the
15 minute timer but Nick Gammon does. He helped me with an ATtiny85 Project
You can find him at this link. http://forum.arduino.cc/index.php?topic=149015.0
Post your question in PROGRAMMING. with the title "How do you make a 15 minute count-down timer with ATtiny85 ?"
Wait for some responses before trying to contact Nick. He doesn't like technical questions via personal message . He won't answer them. You can run the whole thing off a 9V battery probably (not sure about that but it sound reasonable). All you need is the ATtiny85 and a loud PIEZO buzzer. You could make it very small. Crossroads would be willing to build them for you. He has his own electronics company. His email address is cardinalflyer@comcast.net .