Review on SMAKN® Voltage Transformer Module Active by Marcus Curry

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, which doesn't provide much headroom for precise measurements. I think your best bet is to buy transformers and build a circuit to measure the input voltage. I used a transformer with an AD8436 true RMD to DC converter. I'll admit the chip costs $12 (Mouser) and is in the QC-20 physical format, so you'll need a schmartboard or equivalent to solder the chip. But the results are excellent. There's also an AD8436 predecessor chip from Analog Devices, which is an 8-pin DIP connector, which might also suit your needs. Also, the seller has no idea how this IC works, so don't expect any support from the seller. ----- ----------------------- -- ------ ------------- --------------- --------- --------- Original Review I agree with Alex to. It would be helpful if the module came with documentation. With an input voltage of 121 VAC (no built-in trim adjustment) and using a regulated DC supply, I measured an output voltage of 1.457 VDC at Vcc = 3.00 and 2.4982 VDC. with Vcc = 5.00. Since the module draws less than 2.47mA at 3Vcc and 4.8mA at 5VVcc, you can probably safely power it from your Pi or Arduino's regulated output. If you don't use one of these devices to supply Vcc to the module, you'll probably need to build a regulated power supply with a zener diode or LMxxx - otherwise the measured output is meaningless.