110/230v INPUT board for home automation

Hi !

i'm starting a new project for my home automation, using an arduino.

The plenty of Modules / shields / boards / apps developped by smart people around the world, is truly astonishing!!!

As an electricity technician, in france, dealing with material using 12 to tousands of volts, i know that sometimes we need some interfaces.

and there is the point of my topic :

Many variants of OUTPUT boards are available... from a tiny optocoupler micro board, to a massive 16 relays for high voltage/ load applications...

But I can't find ANY INPUT board in the same voltage rating.
I mean a board able to manage a 110vac or 230vac grid voltage as input and create a 5vcc / 3.3vcc compliant with the arduino products.

it's even hard to find a DIY design on the net...

Is any of you working on such a kind of board ? maybe needing an outside look, by a electric and not electronic tech ?

Lets talk about it :slight_smile:


An AC opto-isolator / opto-coupler will do this.

yes i know that, at least i know the principle, but playing with a tiny 4 leg chip, is more complicated that cabling a board, with the right connector, protection etc…

as we are on the original forum, in the proposition board… i make a proposition :wink:

using this kind of board:

is muche easier than playing with relays, optos, led, haeder etc… :wink:


OK - a 5V wall PSU, measure the output with an Analog in pin.

well... that's another way to MONITOR the grid voltage..... but it is not the point....

i'm talking about transforming SEVERAL 230v input into as much 5v inputs for the arduino...

i need a kind of "reverse" of the relay card shown above.

relay board :
arduino 5v input ---> RELAY ---> 230v output

What i need:
230v input ---> "what i need" --->5v output going to an arduino input

let me give you an exemple :

i want to Graft my arduino onto my standard electrical installation.

to lit a lamp, i use the wall rocker.

i can wire a relay in parallel of this rocker, or i can make a back-and-forth.

BUT, i CAN'T KNOW if the light is ON or OFF.... so i need to get the lamp wire ( going to the lamp from the rocker) powering an INPUT of my arduino.... ( through an "input board" )

you see what i mean ?

switching OFF a relay, to UN-power something that can be powered by somewhere else is not enough, I need to know the REAL status of my 230V outpout .

another exemple :

somme wall rocker switch have an integrated light bulb. this bulb is attacher to the OUTPOUT of the rocker, so show you the status of the lamp beneath the wall / door. it's obvious if you have only on rocker, in front of you. but if you have 2 rockers... each integrated bulb is connected to the same output, so when you switch ON any of the rocker, you get the status! i need the same, but going back to my arduino, as a solid 5V

so easy, but so hard to explain :smiley:

You just want to sense high voltage as an input to the Arduino?
This simple circuit creates a 0/5V signal depending whether there is 120V AC present or not.
Changing the resistors to limit current flow it can be used for 230V also.
Would not be hard to make a board with connectors for mating to other boards.


Yes, would be easy to make a PCB with 2 power input connectors, and power/signal/gnd out for a Micro.

If there was a market for more than a couple boards, I'd make one up.