Currently, I am building a smart doorbell that sits on top of my current traditional one. The idea is to close the traditional doorbell's circuit using a relay, but share the existing power source for both devices. My field of expertise is in programming, not electronics... so it's kind of a hurdle for me.
The problem I am facing is getting my Raspberry Pi A+ powered using the available circuit for the current doorbell. The latter is powered through the following transformer: http://www.ecataleg.be/nl/product/413091. I read that I could be using a UBEC to step down the voltage, but I'm wondering if this is going to be a stable enough power supply, certainly when my traditional doorbell is going to consume power on the same circuit.
Anyone has experience with this? Some pointers, maybe? Much appreciated!