Brief sum up (you can go directly to the end if you already read the sum up in the other question)
For a home project I'm making a controller to drive a two-direction 230V motor. For those unfamiliar with this, it is a motor with two windings; when you power one of them the motor turns clockwise, when you power the second it turns counterclockwise.
Excluding the power earth, the motor consequently has three wires. The neutral is always connected to the mains N, while the other two get connected to the L 230V wire when the motor should be turned. Only one winding should be connected to the L at a time, the other is left unconnected.
For this project, space is very critical; please keep this in mind when replying.
Now, in this project I need to monitor the voltage on the two wires, in order to see whether a command is sent, and to monitor the current flowing in the motor, in order to understand when it finished the movement. This question is about the second problem. You can read about the first here.
END OF THE SUM UP
Ok, so I need to detect the current inside the motor. What I thought of is detecting the current through the neutral wire (I don't need to know which winding is absorbing).
The current in the motor is about 500mA - 1A.
I need a simple on-off information (with a threshold which has a fairly high margin).
What I came up with is using something like the ACS712, which gives me the current through the terminals, but it seems quite overkill to me (I don't need to measure it, just an on-off information is fine).
Using a shunt can be ok, but insulation between the 230V and the low power should be enforced.
And... space costraints!
Do you know any technique which is suitable in a small space?