I picked up an adjustable current sense relay and ran the common transformer wire through the inductive coil. I need to take into account steady state current of two (2) video doorbells. The LED light on video doorbells add another small amount if current. I am hoping I can set the detection threshold to only detect the mechanical chime solenoid. I can loop the wire multiple times though the coil to improve sensitivity.
I have it wired up temporarily until I switch to a mechanical chime and install a second video doorbell. I already upgraded the transformer to a 16vac/30watt. I’d post pictures of it in action, but we are not allowed to. 🙁
If my solution does not work reliably, I’ll give yours a try.