Review on SMAKN® Voltage Transformer Module Active by Jeff Jemison

This module is of good quality, but the performance of this circuit clearly has inherent limitations. My observation is that this module is fine for line frequency measurements, but you only get an approximation if you use it to measure RMS voltage. Check out the attached screenshot from my oscilloscope. The yellow curve is the mains input voltage 230 V / 50 Hz (my mains sine wave is distorted, has flat peaks, this is normal) The blue curve is the module output (Vcc = 5 V, the potentiometer is factory set). ). A small phase shift is not a problem. However, you can see that the output waveform is different from the input waveform and that there is more noise (relative to the wave amplitude). This will certainly affect the RMS voltage measurement. (Although noise can probably be reduced with a low-pass filter.)