Locate the doorbell transformer, if replacing. The transformer may be in the garage or utility room, near the doorbell chime or in the attic. The post How To Wire a Doorbell Transformer appeared ...

A wired doorbell system has three components ... you should replace it with one that supplies 30 volts. Locate the transformer and check the voltage. If it's between 10 and 16 volts, replace ...

He reasoned that he could tap into the low-voltage side of the doorbell transformer and watch for the telltale fluctuations that would indicate the bell was doing its thing. The ESP8266 has an ADC ...