ESP8266 Community Forum

- Fri Jun 02, 2017 8:46 am #66639 I am trying to figure out how to use NodeMCU with ACS712 - 30A. I have read through a lot of documentation and post around people using that and the issues with ADC only supporting 0-1V and people building a voltage divider with amplifier but what I haven't found is how to apply this to AC current, most examples are using DC current.

I am building a controller for a whole house fan and wanted to get the power consumption reading, I could switch the microcontroller, but I really like the ESP8266 and I have most of my project already working beside this one component. Any help would be appreciated.

- Fri Jun 02, 2017 11:44 am #66645 Voltage scaling is the easier problem. Use a resistor voltage divider. The more significant problem is what to do with the AC waveform.

Two of the product the company I work for use that type of sensor. On one product we have a resistive load. We only use the sensor to determine a fault condition. In that product we just look for the peak in the waveform.

In the other product we want to know the actual power delivered to the load. That requires us tracking the AC waveform and doing calculations to derive the current and that is more work.

Other products I have designed in the past have used special chips used for utility power meter use. That is my preferred method when we need better accuracy. The special IC does most of the work in determining the measurements.