I've posted a couple of times and received good information, and I'm hoping I can get an answer to this question.
I'm building a chime doorbell. I'm OK with the arduino portion, actuating the bells, sensing actuator position - what I have an issue with is dealing with a standard 12v lighted doorbell button.
This was previously discussed here: http://forum.arduino.cc/index.php?topic=186352.0
But the solution was to replace the 12v bulb with a LED and resistor and to run it off of 3.3v.
It's going to be a gift, so I want it to be as painless as possible to install. Basically, I want to hang it on the wall and use all of the normal connectors that a normal homeowner has when connecting a regular doorbell. 2 sets of connections, 120vAC and standard lighted 12v doorbell button wiring.
My design includes a 12v/5v regulated power supply, so I have 12v available to drive the doorbell button lamp, but the arduino isn't capable of accepting a 12v input without letting out the blue smoke.
A possible solution that I've come up with is to use a 12v optocoupler. This one (linked) looks like it would do, but I'm not entirely certain this is the solution.
The idea is that I'll feed 5v through the switched side of the optocoupler. When the doorbell is pressed, it closes the optocoupler allowing the 5v to pass to the arduino. My concern is that the current going through the bulb will trip the optocoupler.
How do I overcome this? What would you do to use an unmodified 12v lighted doorbell button with an arduino?