I have a dumb button on the door that when touched (by dog’s nose) sets off a chime plugged in to an outlet.
I know I can plug the chime into a smart plug but looking at other options to detect when the chime goes off.
Goal is to tts if the gate (hidden from view of door) is open (existing door sensor) is open when the dog wants to go out.
What’s the voltage in the button?
You probably could use an ESP to detect it
The button is wireless, battery powered unit stuck to the door itself. So essentially it’s a battery doorbell with a remote, plugged in chime.
I haven’t taken apart the chime yet and the more I think about it, the energy monitoring plug is probably the option that makes the most sense. It’s just a plug we walk by daily so not having it stick further out would be nice. It’s also a GFCI outlet so cramming a monitoring device in behind it would be tough.
433 MHz? Time to add a new protocol to Home Assistant: rtl-433.
Oooh, didn’t think of that. I have the receiver when I was playing around with other devices. Will see what the button transmits on.
You can also consider something like a Shelly PM which can be hidden inside the wall box, if you have space.
You stopped one sentence too soon 
Maybe I did!
I was referring to this:
I assumed you mean that when the chime goes off, you’ll be able to detect a change in power, given you were already considering a smart plug.
Before you start wiring Shelly, measure the difference of power draw of your “chime”. Shelly can’t reliably sense some milliwatt differences.
Though it may be possible. I could even 3d print a new, larger case for the chime itself and put the Shelly in 'after the plug ’
It is 433mhz so that’s definitely an option if I want to go that route.
Thanks all! This gives me a few ideas to ponder.
I had an old Zotac computer ($20 on eBay) running Ubuntu that was gathering dust because it is the absolutely slowest computer in the house. I installed the RTL-433 app on it and plugged in a rtl receiver. Watching MQTT explorer I was seeing neighbors’ devices as well as mine, and that was with the rtl receiver in the basement.
That difference would be so small that you would likely get false positives.
Yeah, quoting me like that doesn’t reflect what I said. I didn’t say it was possible at all. I was just following OP’s line of thought. “I assumed you mean that…”
Right, I missed that from post #3, I see. I’m not in the US, so not familiar with those standards, but I’ve seen rants about it.
Haha oh no worries at all. I just thought it was funny.