SMAKN® Voltage Transformer Module Active Review

I use two of these devices to measure AC voltage in my home energy monitor and generator. I am using Nodemcu with Arduino and Emonlib. It was very easy to get it working. After calibration it turned out +/- 0.3V. I just want to detect power dissipation and determine when the generator starts, so ideal voltage levels are not critical to me. The pinout is on the bottom of the device. I tested both 3.3 and 5.0V. Everything worked for me in 3 minutes.

So I bought this to use as an isolated readout voltage for my power monitoring project. I need a low voltage AC signal that I can read and relate to the line voltage. that may be ok though as I'm also power ready, at the same time this device has some issues. I get random spikes in my oscilloscope output. I'm not sure where the spikes are coming from. If I read the tip and apply that voltage to the current, I'm far from the power supply. So I can't use it for its intended purpose.

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…

This module works but it has no specs, no paperwork, no specs, not even from the manufacturer LC Technology, so I am deducting a star because I had to waste time clarifying it. To save you the headache, the bottom line is this: if you connect the green terminal L to mains and N to neutral from a 120V/60Hz source, the module outputs a DC waveform of 60Hz relative to it Vcc off. Vcc can be between 3.3 and 5V DC. At 3.3 VI the wave rises and falls between about +1.35V and +0.9V. So if you take a…

UPDATED April 08, 2021 I downgraded all of these boards to 0ne Star in my review. There are two reasons for this: 1) The DC output is directly related to the input voltage of the power supply. The output voltage behaves linearly to the supply voltage. If your supply voltage changes by millivolts, the measured output voltage will change accordingly2) Since the input power is unipolar, you need to adjust the multi-turn potentiometer so that *at rest* with the input grounded, the output is 2.5V…