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I want to record the AC current time stamp data into my RaspberryPi from current sensor (22mV/A sensitivity) via an ADC (12 Bit resolution) that is being supplied to my mobile.

The input side the charger reads (110-220 V, 50 Hz, 0.3A).So we can expected a sinusoidal wave for the current time stamp with maximum current restricted to 0.3A.

However, on plotting the time vs current below graph is achieved which is obviously wrong:

enter image description here

Can somebody please let me know why am I not getting sinusoidal waveform, I would be very much appreciative.

Ranjan Pal
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    The current being supplied to the phone charger will first depend on the load being drawn by the phone. Assuming the phone is drawing the max of 2A, that's 10W of power. At the charger input with 220VAC, it's an input of 45mA. (assuming 100% efficient). With that sensor, that's about a 1 milli-volt (neglecting some details about peak vs. rms). 1mv will be extremely noise sensitive and hard to measure with this setup. Finally the power factor of the charger will probably not be 1 so the current will not be sinusoidal but probably "spiky". – user1040087 Dec 09 '20 at 15:28
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    Also be careful: the current flow at your sensor will sinusoidal so it will be both positive and negative. I can't find details on the sensor but if we assume the negative current flow is represented by a negative voltage, the ADC will see a negative voltage and that part may not like that. I doubt the sensor can provide enough power to blow up the ADC but its still not a good idea. If the current sensor biases itself at mid supply, this may not be an issue. – user1040087 Dec 09 '20 at 16:46
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    Actually a noise free setup depends on the build along with the actual voltage. Long wires pick up noise. Close proximity to strong signals pick up noise. The output resistance of the sensor make it more susceptible to noise. Also I computed the "best case". Your phone will NOT draw 2 amps. It will probably draw a max of about 1A. But only when the battery is charging hard, the display is on, it's sending lots of data over cellular, GPS is running, etc. When it's idle the current will be even less. The link to the sensor times out. :-( – user1040087 Dec 10 '20 at 13:33
  • Thanks a lot @user1040087 for your valuable feedback. – Ranjan Pal Dec 10 '20 at 14:27

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