Help me build AC voltage monitor for ADC of a PIC chip

[rostec]

Hi,

I am a bit stuck on the best way of doing this. I want to build a 0 to 250V AC Voltage monitor circuit to connect to the ADC of a PIC chip.

I need to be able to monitor both 220vAC and 110vAC and detect if they go over or under voltage so I can program my PIC to decide what action to take.

Do I use some sort of opto of some other form of isolation?

Thanks
Niall

 

[IanP]

Re: AC Voltage Monitor

The easiest way is to use a small transformer and step down voltages from 220/110 to 5Vac, then rectify this and measure it on a 0-5Vdc ADC..
Good luck..
IanP

 

[VVV]

Re: AC Voltage Monitor

A small transformer designed for 220V operation, followed by a rectifier using an opamp, to remove the error due to the diode voltage drop.