Tweeting Doorbell

I started this project back in June, hoping to accomplish two main goals: learn a bit more about microprocessors/sensors/RF and keep the dog from barking when the door bell rang. Since training my dog wouldn't have allowed me to buy fun toys and play with different sensors and RF, I decided to rig up a door bell detection system.

The detection system uses a doorbell tester, which has a tiny light bulb that lights up whenever the doorbell is connected. This attaches right to the existing system. I then used a photocell as an input to my ATMEGA168 (with Arduino bootloader). I didn't want to mess around with transformers quite yet, so this optical/electric coupled circuitry did the trick.

Here is a shot of the photocell I used to detect when the doorbell tester lit up:

Here is a shot of the photocell rigged up inside the doorbell tester:

A little while ago I had put together an "Arduino" from scratch, essentially just exposing the inputs and tying in the necessary supply connections to the ATMEGA168 microprocessor. Here is a quick video of the project.

And a few shots of the arduino board:





Finally, here is the system attached to the doorbell wires. I have an enclosure that covers this system up. You can also see the RF transmitter that I use to send an RF signal and alert the receiver (which does all the tweeting / text messaging).



All that is left to talk about is the receiver system sitting by my Mac Mini. This system detects the RF transmission and pushes a message out through the USB serial interface. On the Mac Mini I have a python script running which waits for the message on the USB serial port and then sends a text message to my wife and I, as well as tweets to twitter.com/geis_door.