I am planning to do home automation using Arduino.

It includes a manual switch and can be also controlled by Arduino.

My problem is I want know the status of the bulb/device or socket. Recently I learned about the ACS217, the problem with ACS is it can measure very large current more than 1 amp.

So I came up with the design below. Should I go ahead with this or are there better solutions?


  • \$\begingroup\$ The LED will be ON when the switch is closed, and doesn't take into account whether the bulb is drawing current or not (blown bulb). If this is what you want then your circuit seems OK. \$\endgroup\$
    – Roger C.
    Dec 14, 2014 at 10:51
  • \$\begingroup\$ I tested this CKT and works fine. Is there anyway i can use ACS to detect very less current 0.1 to 5 amps ? \$\endgroup\$
    – naren
    Dec 15, 2014 at 12:20

1 Answer 1


Use a NPN optocoupler instead of a LED and a LDR. You'll find it easier to work with since you can treat it as a normal transistor and put it between ground and an input with its pullup enabled.


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