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I know I have asked similar questions before, but I have switched sensors and encountered interesting results that I do not understand.

Purpose: I intend to use an AC current sensor to measure electrical current flow running through a simple table lamp, and record these results on my raspberry Pi. I want to record the results in Amperes.

Setup: I am using an SCT013 (rated max current 100A and output is 50mA, 100A:50mA), clamping it around the hot wire running into the lamp. Then after I plug the 'audio cable' output from the SCT013 into an SKU_SEN0211 AC current sensor. I then plug the out put of this current sensor into an MCP3008 ADC on my breadboard, with a 5V reference voltage. From there I measure the result on the Raspberry pi.

so,

SCT013 (100A:50mA) > SKU_SEN0211 > MCP3008 (5V ref) > Raspberry Pi

Results The results read from the Pi seem intuitive at first. They hover at around 10 when the light is off. Shoot up to ~200 when one of the lightbulbs in the lamp is on, and then up to ~400 when the second lightbulb is on. HOWEVER, when I plug in a different SCT sensor that is rated (30A:1V), the results hover at 10 when the light is off, but only go up to ~20 when both lights are turned on.

My Thought Process Since the MCP3008 is a 10-bit converter, in order to convert the result read to voltage I have to do (10/1023) * 5V or, (Vout/1023)*Vref? Which comes out to around 0.09 V or 0.09A?

Question: I don't know how to interpret the read result properly depending on the current sensor I use, and I don't know how to convert that result to Amps. I also have no idea how the signal is transformed as it passes from the AC current sensor to the ADC?

Useful data sheets

SCT013 and AC current sensor https://wiki.dfrobot.com/Gravity_Analog_AC_Current_Sensor__SKU_SEN0211_

Guide I was following but don't fully understand https://www.poweruc.pl/blogs/news/non-invasive-sensor-yhdc-sct013-000-ct-used-with-arduino-sct-013

  • Comments are not for extended discussion; this conversation has been moved to chat. – goldilocks Dec 31 '19 at 12:28
  • @Tuomas Talvitie, if you need me to reply sooner here or in the chat room, you can add the @ sign in front of my username. Cheers. – tlfong01 Jan 10 at 5:08

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