GND is for Arduino only.
No connection to the Wall Gnd.
And, it was not stated here to do any such thing.
If you can not read a schematic - then do not post crittique here in the forums.
Actually, I have job experience (in a Nyc company) expanding (new) X10 Devices for Household control on the home pc, and also providing a Home Web Server to allow Users to Monitor their Household alarms from the internet (say at work or on vacation). The product was marketed.
I designed / built the circuitry to connect a Micro on 60hz Household power - using a 120KHz carrier.
And, wrote the code to extend Data onto the X10 codes.
As I remember, the interface circuitry was close to my suggestion here:
- basically just a RC for Ac of 1Mohm and 1uF connecting the Micro to the 110Vac power.
I also used a Triac to control 110vac bulbs from the micro. The 1M was safe.
Didn’t have any problems. Had fun blinking lights across the office.
My circuits don’t ‘blow up’ or smoke. - Maybe yours do.
But, I think this is beyond the capability of the audience here.
And, will not post the full circuits here.
I clearly Advise NOT to do this - considering that you obviously express that you lack the EE knowledge.
You could start with a High-Voltage Rectifier-Bridge then a High-Impedence Resistor-Ladder.
220 V --
VAC -- ^
*---- | ---------*
| | < R1M
| *-----+ >
| | | |
-- V | *----------*---> Adc0 : Arduino
^ -- | | |
| | | < R10K -- C10nF
O------*-------* | > --
| | |
+------*----------*---> Gnd : Arduino
You could then Monitor the Voltage on the Arduino Adc0/A0 pin.
C10nF would need to be assigned dependent upon the Timeframe of monitoring 1x/sec or 1x/msec or 1x/10sec, etc.
This is under the assumption that the Arduino is running off of a Battery, and Not connected to any pc.
Please ignore any Kiddie / Trolls advice above here - who also state above that they lack actual EE knowledge or experience.
They seem to sugest depending upon if the circuit ‘Smokes’ or not to verify high voltage circuits.
Something I Deffinately would not do - And Deffinately Advise Avoiding.