I'm making my own two way intercom for my house. There will be a speaker and microphone above the front door of my house (as well as a camera). When someone rings my doorbell, I get a notification on my phone and am able to see the video.
The issue is that when I enable the microphone on my phone to talk to the person, I want to disable the outside microphone automatically to prevent feedback.
I'd like to do this with hardware. Can I do this with an NC relay to cut power to the mic; having the speaker voltage controlling the relay coil?
EDIT: Below is what I'm trying to accomplish. I ordered a few sound activated switches, but they will not work for my application. After some more research I think I found what I'm looking for...line audio detectors. Problem is the few for sale are audiophile devices upwards of $100. So I'm going to make my own. Just need some advice on the questions in my schematic.... (https://i.stack.imgur.com/o5nma.png)