I am going to start building this little project I have been wanting to do for a long time. I am wanting to build a door chime that goes off as the door is opened. I will be installing it in my business that has an existing door sensor for a security system that is still in use. The system uses 13v DC as the current sent out to all sensors. Its just a standard reed switch on the door.
My idea was to see if I could just splice into the existing sensors wiring and run it to the Arduino to trigger the mp3 or whatever music file I choose to play using the Adafruit Music Maker Shield. Obviously the Arduino would need to not interfere with the voltage going to or from the reed switch, only activate the tone once the voltage is either applied or taken away. I haven't figured out yet if the voltage is always on and off when the door is open or always off and on when the door is open. But either way should be simple to program I would think.
I know the alarm company probably wouldn't approve but if this works how I think it will they will never even know.
Is this possible with the arduino?