AC voltage sensor - 250V
A voltage transformer ideal to measure AC voltage with a microcontroller. It has high accuracy, good consistency for voltage and power measurement and it can measure up to 250V AC. It is simple to use and comes with a multi-turn trim potentiometer for adjusting the ADC output.
Please note that you have to turn the trim pot quite a few times to be able to see the change in the ADC output.
- Measure within 250V AC
- Onboard micro-precision voltage transformer
- Analog output corresponding quantity can be adjusted.
- Good consistency, for voltage and power measurement
- Very efficient and accuracy
- Output Signal: Analog 0 – 5V
- Size: 49.5 (mm) x19.4 (mm)
- Operating temperature: 40ºC ~ + 70ºC
Reading an AC input on an ADC is a pain as the only way I could figure was to sample as fast as possible and storing maximum and minimum values to calculate peak to peak voltage. I then decided to do this in hardware and that required 3 parts: a 10uF electrolytic capacitor, a bridge rectifier and a 100K resistor. Connect the output of the module to the AC side of the rectifier. Connect both the 10uF cap and 100K resistor over the +/- output of the rectifier and tie the negative output to the ground of the ESP32. Connect the positive to the chosen ADC pin of the ESP32 and voila you no longer have to contend with an AC on the ADC input.
NOTE. Be aware that there will be a roughly 1.4 to 1.6v voltage drop due to the diodes in the rectifier, so you will need to calibrate the ESP32 ADC values.
You would expect 250v to output 5v, but on 2 units I did not find this to be the case. I did discover that it can be adjusted (using the small ****) to set it to output a desired output for a given voltage - e.g. to output 3.3v for 230v in to suit a 3.3v microcontroller like the ESP32 range that can handle max 3.3v on their ADC pins.