I have a circuit that interfaces to the analog input of a PIC16F687. It then drives 6 LED based on the current and then send it serially to be saved in a file.

The circuit works fine on a resistive AC Load but when used with a 120V 1.5HP universal motor the reading is lower than what is expected. The circuit, due to cost does not have a lot of filtering other than the AC output of the ACS712 to a DC voltage.

This is my first time using a hall effect type sensor and not sure if it is picking up the magnetic field of the motor. The circuit board sits on top of the motor housing.


Any suggestions would be appreciated.

David

 

cherck out power factor, phase differences cause differing readings.

 

The output voltage is a sine wave proportional to the input current superimposed on a DC voltage of 1/2Vcc - Vdiode. Is this what you are getting?
It would be helpful if you clarify What is the 'expected reading'? Is the motor current measured with a meter and compared with the output?