Adapter PCB for Peacefair PZEM-004T Energy Meter

Inspired by the video linked below, I made an adapter PCB for the Peacefair PZEM-004T, to allow it to measure AC voltages less than 80V. I also added an adjustment to calibrate the voltage sensing, and provision for a serial to USB converter. I did try to make the current measurement adjustable also, but ran into problems with that.
Video by TheHWcave:-
• Modifying the Peacefai...

[@N100NXX]

Many thanks for doing your investigation in this affordable energy measurement device and pointing out the issues with discrepancies caused by the extraneous devices giving the fluctuations in the readouts.

[@t1d100]

👍👍👍

[@BjornV78]

Another crude way to power these Peacefair with LCD screen power meters, is to measure the voltage over that large capacitor,
i think it's arround 5V, and to "inject" that amount of voltage from a external powersupply through a diode (to prevent backfeeding the mains into the external powersupply) in parallel over that capacitor. This external powersupply can offcourse not be used to power something else in the same cabinet.
Below 80V of mains, the power meter is powered from this external powersource, and from 80V and beyond, the meter is powered by the mains.

[@bertoid]

That's an interesting method, though I wonder if many circumstances could use it.
Presumably the external supply would in most cases operate from the mains, which could just be used directly. It would be a strange setup where there was a power supply, but no mains to drive it. Battery backup maybe? (sort of a UPS for the PZEM)
Depending on circumstances, the PZEM might still need a modification to separate its supply input from its measuring input.
Something to keep in mind though...

[@BjornV78]

@@bertoid , the measuring input works fine when using a external powersupply, the problem of no screen below 80V is due the "capacitor dropper" circuit not delivering enough juice to power the meter.
With a external supply connected in parallel over the big capacitor, the meters shows 0V when no voltage source is connected to the input. Like i mentioned before, you need to add a diode, to prevent backfeeding into the external powersupply. Also due the capacitor dropper circuit is not isolated from the mains, the external powersupply now also become hot (live), so this external powersupply can't not be used for anything else in the same projectbox. Instead of using a mains powered external powersupply, you can also use a battery pack, so that the meter becomes portable. Grtz.