A sensor/detector for connecting an alarm system to HA

[torado (Aleksey)]

Hi all,
I’m trying to find a way to connect an alarm system to HA. The alarm system has a 12V output that can be used to connect to other devices. The output is triggered when the alarm goes off.

I thought to put a sensor/detector on that output to be able to read its state with HA. The HA should only notify me that the alarm is triggered and nothing more.

Could you please recommend me what kind of sensor/detector this might be?

Thanks in advance.

[pkscout (Kyle Johnson)]

If you’re up for a little soldering, it looks like you could build one using an ESP32 device, a DC sensor, and ESPHome.

I found this thread:

Measuring 12v on ESP32 or ESP8266

I’m looking to make a device that will monitor the voltage of a generator battery that should be around 12v, maybe as much as 14v. I have a plan on what to do, but would like confirmation before I attempt this. May start off with a esp8266 but may switch to a esp32 to be able to hook up more than 1 monitored point on the generator. I would have 12v or so coming from the battery to a DC0-25v that will divide the voltage by 5. The esp32 or esp8266 can handle input voltages up to 3.3v. So, as long…

That mentions this sensor:

INA219 DC Current Sensor

Attach that to the I2C bus of an ESP32, and you should be able build a YAML file for ESPHome that will get the device to report the state to Home Assistant.

I’m doing something similar with a different sensor to detect an AC current.

[torado (Aleksey)]

Hi Kyle,
Sorry for the slow reply, and thanks for sharing the thread and your suggestion with me! I’ve read it, it’s a very informative thread.

I think, using the Shelly Plus Uni relay would be a good solution for me as it requires less work around it.