I have my tv that when is on will provide a +12V on a pin.
I’d like to check it and take an action when on…
which physical sensor can I use to get that input?
I was not able to find anything… I just need to read the status.
then via Automation I’ll activate scenes etc…
any suggestion?
Most people I know use a smart plug with power metering to see if the power consumption exceeds the standby usage. That is probably safer then tapping into some port? If you know how much power you can draw from the 12V you could consider linking a small relay to a door sensor.
Is it the SCART connector?
If so make sure to use an optical isolation between the TV and the ESP.
The voltage can spike a lot when it turns on.
Here is my sensor I built some time ago.
Very nice! in reality is a connector on a projector and it’s use is exactly to signal the status… but the idea of optical isolation is very good!
but I was looking for something already existing. your project is nice but fully DIY 
I’m puzzled no “input” exist for domotics 
that would be a smart idea but to protect the projector I have an UPS so I cannot use a smart plug as the connectors are like the ones for PC and not a normal plug
Is the UPS connected to a NAS or something similar that can monitor the UPS status? My UPS also shows how much load it handles. Maybe that is sensitive enough?
Good suggestion. I’m trying to check it, both sensitivity as well as lead time to update.
If is too long it could not trigger the scenes correctly
The easiest non DIY is probably a Shelly running on 12 volts.
If it’s not to much for the projector.
That way the Shelly will be online when projector is on, else unavailable.
An expensive way, but easy to do.
But you need to check that the projector can supply enough power for the ESP.
thank you… I was thinking something similar with this one: Sonoff SV Safe Voltage WiFi Wireless Switch Smart Home Module
it’s consumption is very low
or the Shelly Uni - Shelly Cloud but it is more costly and higher power consumption