I’m a simple kind of guy.
I am using the Scout alarm monitoring, and many times my wife or I have set off the alarm because we didn’t realize it had been set (i.e. one of the kids set it before we went to the store, and we come back 15 minutes later and trip the alarm). A couple of times we haven’t realized the alarm was triggered until a very friendly police officer shows up at our door.
I wanted an alarm siren that wasn’t going to cost $50, to ring when the alarm is actually going off - and I have since thought about extending that to an alarm that beeps every X minutes to let you know that the alarm is armed (like if someone arms it while you are home accidentally).
Remember I said I am a simple kind of guy.
I accomplished this with a nodeMCU ($2), a LOUD 5v piezoelectric buzzer (10 for $1.99) and a single 5v relay ($1.99).
$6 for the whole setup, about an hour to get it working using the ST_Anything device handler
Now when the alarm is triggered, the buzzer rings (screams loudly) for a set amount of time (programmable within the ST_Anything sketch).
The continuous screaming of the piezo buzzer is annoying so I’ve thought about making it “beep” instead, just adding an adjustable flasher to the buzzer.
Now I can easily use SmartThings to ring the buzzer, say, when a door opens or stays open or closes or a light is turned on…
Maybe that’s too simplistic for you, but like I said - I’m a simple kind of guy.
Honestly this is really overkill for the nodemcu, too many free gpio pins, essentially I could have done this with just an esp8266 but then I have to deal with the power (esp8266 is 3v, nodemcu has 5v input plus the piezo buzzer and the relay are 5v)