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Not sure if this is possible, but could I use my existing doorbell setup to power an Arduino? I'd also like to preserve the existing chime's functionality either through the existing button or triggering it through the arduino.

My doorbell chime is made by Nicor and its input is 120VAC, but outputs 12VDC. This seems to be a very unconventional setup, but I've confirmed its output with a multimeter (it's also printed on the chime itself). The chime is very similar to this: http://www.amazon.com/Nicor-18888-Door-Chimes/dp/B006T38PTU (only difference I can see is the output). The 12V line runs to my front door where it's connected to a light up button. Here is a picture of the button's circuitry: http://imgur.com/IjA50rT

What I'd like to do is use the chime's 12VDC output to power the arduino so I don't have to rely on another power source or batteries. I will be adding smart features to the doorbell via the arduino, but my main hangup is getting power to the arduino. I've tried connecting the doorbell wires to VIN and ground, which successfully powers on the Arduino, but it also triggers the chime. It appears closing the circuit triggers the chime to play.

Is this possible to do?

share|improve this question
1  
Connecting 12v to an Arduino's VCC pin would likely destroy it. You want the Vin pin. But you also don't want to be in series with the buzzer - the voltage drop from that second mistake might be the only reason your Arduino still functions. – Chris Stratton May 20 at 17:34
    
Sorry, I actually meant the VIN pin. – SterlingW May 20 at 17:39
    
The button board looks amazingly complex for "just a button". As others have noted, it may just carry signal-level voltage, not enough to power the Arduino. Plus, if pressing the button closes a circuit, the +12V might disappear at the exact time when you want it - when you want to hear a chime. – Nick Gammon♦ Jun 20 at 21:02
up vote 0 down vote

You need to find the transformer for your doorbell system and take the power from there. It seems like somehow you are using the signal wires for the door bell instead of the power wires.

The door bell transformer should/could be in a utility room, closet, by your heating and air unit. once you find that look at the output of the transformer. I know some are AC 12 volts, and I feel like that arduino will not like that...

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The transformer is part of the chime and it's connected to mains power. The chime takes 120VAC in and outputs 12VDC. If you take a look at the amazon listing (amazon.com/Nicor-18888-Door-Chimes/dp/B006T38PTU), you can kind of see what the wiring looks like (see the other images). – SterlingW May 20 at 17:43
    
So get a little 12Volt or 9volt transformer and wire it into the mains at the door chime. I bet you have one laying around the house! – Mason Younger May 20 at 19:03
    
But the problem is that I am unable to run additional wires so I'd like to use what's already there – SterlingW May 20 at 19:10
    
I understood that you were putting the arduino by the door chime, if so You wouldn't be running any extra wires. – Mason Younger May 20 at 19:34
    
Sorry, I'd actually like to have it by the button – SterlingW May 20 at 19:54
up vote -3 down vote

You must connect the arduino vin pin to the doorbell 12vdc and it should work. Edit: Now I understood the chimes out, that is connected to relay coil driven by the button. If the relay is mechanic you can play with delay times and use pwm to drive your arduino without turning on the chime. The system I have described is used in NEST thermostat, that self powers with heater relay wires.

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without having seen a wiring scheme is clearly unresponsible. – Ariser Jun 21 at 11:20
    
This does not work because it triggers the chime to go off constantly. – SterlingW Jun 21 at 19:34

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