I have a classical doorbell (with transformer) that I would like to connect to the “internet”.
The idea is when someone rings at my door that this sends an MQTT message to my MQTT broker (or alternatively communicates this to my home assistant)
The requirements are:
- existing doorbell system should be kept.
- low cost
- can be installed with a minimum of changes.
As solution I was thinking of detecting the current using a current sensor.
This current sensor is then connected to an ESP8266 NodeMCU (or other cheap device) that will detect increase in current when doorbell rings and publishes an MQTT message to my MQTT broker.
Here below a picture of my transformer showing the wires that can be used to measure current.
Regarding the current sensor, I have found following sensors:
- ACS712 5A AC and DC Current Sensor Module - there are also 20A, 30A versions
- TA12-100 Arduino AC Current Sensor
- HW-670 5A range single phase AC active output current transformer module current sensor module
Any advice would be very welcome.
I would prefer to install it at low voltage side. I guess as the currents are small, I need to chose one with low A (I guess 5A is sufficient).
Regarding the wiring of the sensor to the nodeMCU. If anything more is needed besides connecting the sensor with 2 wires to the nodeMcu then I would love to hear this.