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How to make a mains power AC voltage meter for input as an MCU sensor? Answered

I live off grid and need to keep an eye on various properties from various power sources.
This includes,
VDC 12-24 from the solar panels,
VAC 220 from the fallback generator.
VAC 220 from the inverter into the house.
I can find off the shelf sensors for the AMPS which can feed into various MCUs
I can find circuits to build sensors for AMPS, not a problem.
What I cannot find is either off the shelf VOLTS level indicator sensors or circuits that do not involve plugging in walt-warts to bring the voltage down.
Space is a premium so ideally I wanted to plug a live and neutral wire into one end of a pcb and have hopefully an analog 0-5 VDC representation coming out of the other. I have in my box some small 6, 9 and 12 unregulated mains VAC transformers.
I find it strange that I can buy from China a small LCD with Volts, Amps, Watts and Hertz for about 8€ but not a barebones system which is what I need.
So if anyone knows how to either hack one of these Chinese meters to give MCU usable input data or can help me build a meter, I would be very grateful.
My son-in-law is an electrician but electronics is alien to him. So he can oversee the safety on big stuff.
Thanks and kind regards,


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4 years ago

Just use little transformers, and rectifiers, you aren't really interested in the level down to mV.


Answer 4 years ago

You MIGHT only be interested in the presence or absence of 110 or 220, all you need to do that is an opto-isolator and a couple of resistors.